diff --git a/src/openrct2-ui/WindowManager.cpp b/src/openrct2-ui/WindowManager.cpp
index 5d3f4d978a..1e640a268b 100644
--- a/src/openrct2-ui/WindowManager.cpp
+++ b/src/openrct2-ui/WindowManager.cpp
@@ -554,7 +554,7 @@ public:
             auto viewport = window_get_viewport(mainWindow);
             auto zoomDifference = zoom - viewport->zoom;
 
-            mainWindow->viewport_target_sprite = SPRITE_INDEX_NULL;
+            mainWindow->viewport_target_sprite = EntityId::GetNull();
             mainWindow->savedViewPos = viewPos;
             viewport->zoom = zoom;
             gCurrentRotation = rotation;
diff --git a/src/openrct2-ui/scripting/CustomMenu.cpp b/src/openrct2-ui/scripting/CustomMenu.cpp
index 3e1e673096..4faf3389dd 100644
--- a/src/openrct2-ui/scripting/CustomMenu.cpp
+++ b/src/openrct2-ui/scripting/CustomMenu.cpp
@@ -194,7 +194,7 @@ namespace OpenRCT2::Scripting
 
             if (info.SpriteType == ViewportInteractionItem::Entity && info.Entity != nullptr)
             {
-                obj.Set("entityId", info.Entity->sprite_index);
+                obj.Set("entityId", info.Entity->sprite_index.ToUnderlying());
             }
             else if (info.Element != nullptr)
             {
diff --git a/src/openrct2-ui/scripting/ScTitleSequence.hpp b/src/openrct2-ui/scripting/ScTitleSequence.hpp
index 411fb29c4d..643a12606d 100644
--- a/src/openrct2-ui/scripting/ScTitleSequence.hpp
+++ b/src/openrct2-ui/scripting/ScTitleSequence.hpp
@@ -65,10 +65,10 @@ namespace OpenRCT2::Scripting
                 obj.Set("zoom", value.Zoom);
                 break;
             case TitleScript::Follow:
-                if (value.SpriteIndex == SPRITE_INDEX_NULL)
+                if (value.SpriteIndex.IsNull())
                     obj.Set("id", nullptr);
                 else
-                    obj.Set("id", value.SpriteIndex);
+                    obj.Set("id", value.SpriteIndex.ToUnderlying());
                 break;
             case TitleScript::Speed:
                 obj.Set("speed", value.Speed);
@@ -117,11 +117,11 @@ namespace OpenRCT2::Scripting
                 auto dukId = value["id"];
                 if (dukId.type() == DukValue::Type::NUMBER)
                 {
-                    command.SpriteIndex = dukId.as_int();
+                    command.SpriteIndex = EntityId::FromUnderlying(dukId.as_int());
                 }
                 else
                 {
-                    command.SpriteIndex = SPRITE_INDEX_NULL;
+                    command.SpriteIndex = EntityId::GetNull();
                 }
                 break;
             }
diff --git a/src/openrct2-ui/title/TitleSequencePlayer.cpp b/src/openrct2-ui/title/TitleSequencePlayer.cpp
index 6189555c30..53705453f6 100644
--- a/src/openrct2-ui/title/TitleSequencePlayer.cpp
+++ b/src/openrct2-ui/title/TitleSequencePlayer.cpp
@@ -339,7 +339,7 @@ private:
         }
     }
 
-    void FollowSprite(uint16_t spriteIndex)
+    void FollowSprite(EntityId spriteIndex)
     {
         rct_window* w = window_get_main();
         if (w != nullptr)
@@ -502,7 +502,7 @@ private:
     void FixViewLocation()
     {
         rct_window* w = window_get_main();
-        if (w != nullptr && w->viewport_smart_follow_sprite == SPRITE_INDEX_NULL)
+        if (w != nullptr && w->viewport_smart_follow_sprite.IsNull())
         {
             if (w->width != _lastScreenWidth || w->height != _lastScreenHeight)
             {
diff --git a/src/openrct2-ui/windows/GameBottomToolbar.cpp b/src/openrct2-ui/windows/GameBottomToolbar.cpp
index a0a20bb667..e8b35b2622 100644
--- a/src/openrct2-ui/windows/GameBottomToolbar.cpp
+++ b/src/openrct2-ui/windows/GameBottomToolbar.cpp
@@ -594,7 +594,7 @@ static void WindowGameBottomToolbarDrawNewsItem(rct_drawpixelinfo* dpi, rct_wind
                 break;
             }
 
-            auto peep = TryGetEntity<Peep>(newsItem->Assoc);
+            auto peep = TryGetEntity<Peep>(EntityId::FromUnderlying(newsItem->Assoc));
             if (peep == nullptr)
                 return;
 
diff --git a/src/openrct2-ui/windows/Guest.cpp b/src/openrct2-ui/windows/Guest.cpp
index c1a33fd091..6f3ba80e09 100644
--- a/src/openrct2-ui/windows/Guest.cpp
+++ b/src/openrct2-ui/windows/Guest.cpp
@@ -289,7 +289,7 @@ void WindowGuestSetColours();
 
 static Guest* GetGuest(rct_window* w)
 {
-    auto guest = GetEntity<Guest>(w->number);
+    auto guest = GetEntity<Guest>(EntityId::FromUnderlying(w->number));
     if (guest == nullptr)
     {
         window_close(w);
@@ -316,7 +316,7 @@ rct_window* WindowGuestOpen(Peep* peep)
 
     rct_window* window;
 
-    window = window_bring_to_front_by_number(WC_PEEP, peep->sprite_index);
+    window = window_bring_to_front_by_number(WC_PEEP, peep->sprite_index.ToUnderlying());
     if (window == nullptr)
     {
         int32_t windowWidth = 192;
@@ -325,7 +325,7 @@ rct_window* WindowGuestOpen(Peep* peep)
 
         window = WindowCreateAutoPos(windowWidth, 157, &window_guest_overview_events, WC_PEEP, WF_RESIZABLE);
         window->widgets = window_guest_overview_widgets;
-        window->number = peep->sprite_index;
+        window->number = peep->sprite_index.ToUnderlying();
         window->page = 0;
         window->frame_no = 0;
         window->list_information_type = 0;
@@ -518,7 +518,8 @@ void WindowGuestOverviewMouseUp(rct_window* w, rct_widgetindex widgetIndex)
             w->picked_peep_old_x = peep->x;
             CoordsXYZ nullLoc{};
             nullLoc.SetNull();
-            PeepPickupAction pickupAction{ PeepPickupType::Pickup, w->number, nullLoc, network_get_current_player_id() };
+            PeepPickupAction pickupAction{ PeepPickupType::Pickup, EntityId::FromUnderlying(w->number), nullLoc,
+                                           network_get_current_player_id() };
             pickupAction.SetCallback([peepnum = w->number](const GameAction* ga, const GameActions::Result* result) {
                 if (result->Error != GameActions::Status::Ok)
                     return;
@@ -541,7 +542,7 @@ void WindowGuestOverviewMouseUp(rct_window* w, rct_widgetindex widgetIndex)
         {
             uint32_t flags = peep->PeepFlags ^ PEEP_FLAGS_TRACKING;
 
-            auto guestSetFlagsAction = GuestSetFlagsAction(w->number, flags);
+            auto guestSetFlagsAction = GuestSetFlagsAction(EntityId::FromUnderlying(w->number), flags);
             GameActions::Execute(&guestSetFlagsAction);
         }
         break;
@@ -590,7 +591,7 @@ static void WindowGuestShowLocateDropdown(rct_window* w, rct_widget* widget)
 static void WindowGuestFollow(rct_window* w)
 {
     rct_window* w_main = window_get_main();
-    window_follow_sprite(w_main, w->number);
+    window_follow_sprite(w_main, EntityId::FromUnderlying(w->number));
 }
 
 /**
@@ -712,7 +713,7 @@ static void WindowGuestOverviewTabPaint(rct_window* w, rct_drawpixelinfo* dpi)
 
     screenCoords = ScreenCoordsXY{ 14, 20 };
 
-    const Peep* peep = GetEntity<Peep>(w->number);
+    const Peep* peep = GetEntity<Peep>(EntityId::FromUnderlying(w->number));
     if (peep == nullptr)
     {
         window_close(w);
@@ -1075,7 +1076,7 @@ void WindowGuestOverviewTextInput(rct_window* w, rct_widgetindex widgetIndex, ch
 
     if (text == nullptr)
         return;
-    guest_set_name(w->number, text);
+    guest_set_name(EntityId::FromUnderlying(w->number), text);
 }
 
 /**
@@ -1141,9 +1142,10 @@ void WindowGuestOverviewToolDown(rct_window* w, rct_widgetindex widgetIndex, con
     if (destCoords.IsNull())
         return;
 
-    PeepPickupAction pickupAction{
-        PeepPickupType::Place, w->number, { destCoords, tileElement->GetBaseZ() }, network_get_current_player_id()
-    };
+    PeepPickupAction pickupAction{ PeepPickupType::Place,
+                                   EntityId::FromUnderlying(w->number),
+                                   { destCoords, tileElement->GetBaseZ() },
+                                   network_get_current_player_id() };
     pickupAction.SetCallback([](const GameAction* ga, const GameActions::Result* result) {
         if (result->Error != GameActions::Status::Ok)
             return;
@@ -1162,9 +1164,10 @@ void WindowGuestOverviewToolAbort(rct_window* w, rct_widgetindex widgetIndex)
     if (widgetIndex != WIDX_PICKUP)
         return;
 
-    PeepPickupAction pickupAction{
-        PeepPickupType::Cancel, w->number, { w->picked_peep_old_x, 0, 0 }, network_get_current_player_id()
-    };
+    PeepPickupAction pickupAction{ PeepPickupType::Cancel,
+                                   EntityId::FromUnderlying(w->number),
+                                   { w->picked_peep_old_x, 0, 0 },
+                                   network_get_current_player_id() };
     GameActions::Execute(&pickupAction);
 }
 
diff --git a/src/openrct2-ui/windows/GuestList.cpp b/src/openrct2-ui/windows/GuestList.cpp
index e05c6aad21..6d9aa93be7 100644
--- a/src/openrct2-ui/windows/GuestList.cpp
+++ b/src/openrct2-ui/windows/GuestList.cpp
@@ -121,7 +121,7 @@ private:
     {
         using CompareFunc = bool (*)(const GuestItem&, const GuestItem&);
 
-        uint16_t Id;
+        EntityId Id;
         char Name[256];
     };
 
diff --git a/src/openrct2-ui/windows/News.cpp b/src/openrct2-ui/windows/News.cpp
index 7af93494a4..73273b7ef2 100644
--- a/src/openrct2-ui/windows/News.cpp
+++ b/src/openrct2-ui/windows/News.cpp
@@ -237,7 +237,7 @@ public:
                             break;
                         }
 
-                        auto peep = TryGetEntity<Peep>(newsItem.Assoc);
+                        auto peep = TryGetEntity<Peep>(EntityId::FromUnderlying(newsItem.Assoc));
                         if (peep == nullptr)
                         {
                             break;
diff --git a/src/openrct2-ui/windows/Ride.cpp b/src/openrct2-ui/windows/Ride.cpp
index 889e5928b7..5388f5cf06 100644
--- a/src/openrct2-ui/windows/Ride.cpp
+++ b/src/openrct2-ui/windows/Ride.cpp
@@ -1288,7 +1288,7 @@ rct_window* WindowRideOpenVehicle(Vehicle* vehicle)
     if (headVehicle == nullptr)
         return nullptr;
 
-    uint16_t headVehicleSpriteIndex = headVehicle->sprite_index;
+    EntityId headVehicleSpriteIndex = headVehicle->sprite_index;
     auto ride = headVehicle->GetRide();
     if (ride == nullptr)
         return nullptr;
@@ -1489,21 +1489,21 @@ static void WindowRideInitViewport(rct_window* w)
 
     if (viewSelectionIndex >= 0 && viewSelectionIndex < ride->num_vehicles && ride->lifecycle_flags & RIDE_LIFECYCLE_ON_TRACK)
     {
-        uint16_t vehId = ride->vehicles[viewSelectionIndex];
+        auto vehId = ride->vehicles[viewSelectionIndex];
         rct_ride_entry* ride_entry = ride->GetRideEntry();
         if (ride_entry != nullptr && ride_entry->tab_vehicle != 0)
         {
             Vehicle* vehicle = GetEntity<Vehicle>(vehId);
             if (vehicle == nullptr)
             {
-                vehId = SPRITE_INDEX_NULL;
+                vehId = EntityId::GetNull();
             }
-            else if (vehicle->next_vehicle_on_train != SPRITE_INDEX_NULL)
+            else if (!vehicle->next_vehicle_on_train.IsNull())
             {
                 vehId = vehicle->next_vehicle_on_train;
             }
         }
-        if (vehId != SPRITE_INDEX_NULL)
+        if (!vehId.IsNull())
         {
             focus = Focus(vehId);
         }
@@ -1939,7 +1939,7 @@ static void WindowRideShowLocateDropdown(rct_window* w, rct_widget* widget)
 
 static void WindowRideMainFollowRide(rct_window* w)
 {
-    auto ride = get_ride(w->rideId);
+    auto* ride = get_ride(w->rideId);
     if (ride != nullptr)
     {
         if (!(ride->window_invalidate_flags & RIDE_INVALIDATE_RIDE_MAIN))
@@ -1951,7 +1951,7 @@ static void WindowRideMainFollowRide(rct_window* w)
                     Vehicle* vehicle = GetEntity<Vehicle>(ride->vehicles[w->ride.view - 1]);
                     if (vehicle != nullptr)
                     {
-                        uint16_t headVehicleSpriteIndex = vehicle->sprite_index;
+                        auto headVehicleSpriteIndex = vehicle->sprite_index;
                         rct_window* w_main = window_get_main();
                         window_follow_sprite(w_main, headVehicleSpriteIndex);
                     }
diff --git a/src/openrct2-ui/windows/Staff.cpp b/src/openrct2-ui/windows/Staff.cpp
index 60719466af..6d22bf1c4b 100644
--- a/src/openrct2-ui/windows/Staff.cpp
+++ b/src/openrct2-ui/windows/Staff.cpp
@@ -219,7 +219,7 @@ static PatrolAreaValue _staffPatrolAreaPaintValue = PatrolAreaValue::NONE;
 
 static Staff* GetStaff(rct_window* w)
 {
-    auto staff = GetEntity<Staff>(w->number);
+    auto staff = GetEntity<Staff>(EntityId::FromUnderlying(w->number));
     if (staff == nullptr)
     {
         window_close(w);
@@ -234,12 +234,12 @@ static Staff* GetStaff(rct_window* w)
  */
 rct_window* WindowStaffOpen(Peep* peep)
 {
-    rct_window* w = window_bring_to_front_by_number(WC_PEEP, peep->sprite_index);
+    rct_window* w = window_bring_to_front_by_number(WC_PEEP, peep->sprite_index.ToUnderlying());
     if (w == nullptr)
     {
         w = WindowCreateAutoPos(WW, WH, &window_staff_overview_events, WC_PEEP, WF_10 | WF_RESIZABLE);
 
-        w->number = peep->sprite_index;
+        w->number = peep->sprite_index.ToUnderlying();
         w->page = 0;
         w->frame_no = 0;
         w->highlighted_item = 0;
@@ -386,7 +386,8 @@ void WindowStaffOverviewMouseup(rct_window* w, rct_widgetindex widgetIndex)
             w->picked_peep_old_x = peep->x;
             CoordsXYZ nullLoc{};
             nullLoc.SetNull();
-            PeepPickupAction pickupAction{ PeepPickupType::Pickup, w->number, nullLoc, network_get_current_player_id() };
+            PeepPickupAction pickupAction{ PeepPickupType::Pickup, EntityId::FromUnderlying(w->number), nullLoc,
+                                           network_get_current_player_id() };
             pickupAction.SetCallback([peepnum = w->number](const GameAction* ga, const GameActions::Result* result) {
                 if (result->Error != GameActions::Status::Ok)
                     return;
@@ -571,7 +572,7 @@ static void WindowStaffShowLocateDropdown(rct_window* w, rct_widget* widget)
 static void WindowStaffFollow(rct_window* w)
 {
     rct_window* w_main = window_get_main();
-    window_follow_sprite(w_main, w->number);
+    window_follow_sprite(w_main, EntityId::FromUnderlying(w->number));
 }
 
 /**
@@ -603,7 +604,7 @@ static void WindowStaffSetOrder(rct_window* w, int32_t order_id)
     }
 
     uint8_t newOrders = peep->StaffOrders ^ (1 << order_id);
-    auto staffSetOrdersAction = StaffSetOrdersAction(w->number, newOrders);
+    auto staffSetOrdersAction = StaffSetOrdersAction(EntityId::FromUnderlying(w->number), newOrders);
     GameActions::Execute(&staffSetOrdersAction);
 }
 
@@ -1172,6 +1173,8 @@ void WindowStaffOverviewToolUpdate(rct_window* w, rct_widgetindex widgetIndex, c
  */
 void WindowStaffOverviewToolDown(rct_window* w, rct_widgetindex widgetIndex, const ScreenCoordsXY& screenCoords)
 {
+    const auto staffEntityId = EntityId::FromUnderlying(w->number);
+
     if (widgetIndex == WIDX_PICKUP)
     {
         TileElement* tileElement;
@@ -1181,7 +1184,7 @@ void WindowStaffOverviewToolDown(rct_window* w, rct_widgetindex widgetIndex, con
             return;
 
         PeepPickupAction pickupAction{
-            PeepPickupType::Place, w->number, { destCoords, tileElement->GetBaseZ() }, network_get_current_player_id()
+            PeepPickupType::Place, staffEntityId, { destCoords, tileElement->GetBaseZ() }, network_get_current_player_id()
         };
         pickupAction.SetCallback([](const GameAction* ga, const GameActions::Result* result) {
             if (result->Error != GameActions::Status::Ok)
@@ -1198,7 +1201,7 @@ void WindowStaffOverviewToolDown(rct_window* w, rct_widgetindex widgetIndex, con
         if (destCoords.IsNull())
             return;
 
-        auto staff = TryGetEntity<Staff>(w->number);
+        auto staff = TryGetEntity<Staff>(staffEntityId);
         if (staff == nullptr)
             return;
 
@@ -1211,7 +1214,7 @@ void WindowStaffOverviewToolDown(rct_window* w, rct_widgetindex widgetIndex, con
             _staffPatrolAreaPaintValue = PatrolAreaValue::SET;
         }
         auto staffSetPatrolAreaAction = StaffSetPatrolAreaAction(
-            w->number, destCoords,
+            staffEntityId, destCoords,
             _staffPatrolAreaPaintValue == PatrolAreaValue::SET ? StaffSetPatrolAreaMode::Set : StaffSetPatrolAreaMode::Unset);
         GameActions::Execute(&staffSetPatrolAreaAction);
     }
@@ -1236,7 +1239,9 @@ void WindowStaffOverviewToolDrag(rct_window* w, rct_widgetindex widgetIndex, con
     if (destCoords.IsNull())
         return;
 
-    auto staff = TryGetEntity<Staff>(w->number);
+    const auto staffEntityId = EntityId::FromUnderlying(w->number);
+
+    auto* staff = TryGetEntity<Staff>(staffEntityId);
     if (staff == nullptr)
         return;
 
@@ -1247,7 +1252,7 @@ void WindowStaffOverviewToolDrag(rct_window* w, rct_widgetindex widgetIndex, con
         return; // Since area is already the value we want, skip...
 
     auto staffSetPatrolAreaAction = StaffSetPatrolAreaAction(
-        w->number, destCoords,
+        staffEntityId, destCoords,
         _staffPatrolAreaPaintValue == PatrolAreaValue::SET ? StaffSetPatrolAreaMode::Set : StaffSetPatrolAreaMode::Unset);
     GameActions::Execute(&staffSetPatrolAreaAction);
 }
@@ -1268,9 +1273,10 @@ void WindowStaffOverviewToolAbort(rct_window* w, rct_widgetindex widgetIndex)
 {
     if (widgetIndex == WIDX_PICKUP)
     {
-        PeepPickupAction pickupAction{
-            PeepPickupType::Cancel, w->number, { w->picked_peep_old_x, 0, 0 }, network_get_current_player_id()
-        };
+        PeepPickupAction pickupAction{ PeepPickupType::Cancel,
+                                       EntityId::FromUnderlying(w->number),
+                                       { w->picked_peep_old_x, 0, 0 },
+                                       network_get_current_player_id() };
         GameActions::Execute(&pickupAction);
     }
     else if (widgetIndex == WIDX_PATROL)
@@ -1290,7 +1296,7 @@ void WindowStaffOverviewTextInput(rct_window* w, rct_widgetindex widgetIndex, ch
     if (text == nullptr)
         return;
 
-    auto gameAction = StaffSetNameAction(w->number, text);
+    auto gameAction = StaffSetNameAction(EntityId::FromUnderlying(w->number), text);
     GameActions::Execute(&gameAction);
 }
 
@@ -1429,6 +1435,6 @@ void WindowStaffOptionsDropdown(rct_window* w, rct_widgetindex widgetIndex, int3
         return;
 
     EntertainerCostume costume = _availableCostumes[dropdownIndex];
-    auto staffSetCostumeAction = StaffSetCostumeAction(w->number, costume);
+    auto staffSetCostumeAction = StaffSetCostumeAction(EntityId::FromUnderlying(w->number), costume);
     GameActions::Execute(&staffSetCostumeAction);
 }
diff --git a/src/openrct2-ui/windows/StaffFirePrompt.cpp b/src/openrct2-ui/windows/StaffFirePrompt.cpp
index bb606f3888..8268e43f1d 100644
--- a/src/openrct2-ui/windows/StaffFirePrompt.cpp
+++ b/src/openrct2-ui/windows/StaffFirePrompt.cpp
@@ -56,7 +56,7 @@ rct_window* WindowStaffFirePromptOpen(Peep* peep)
     rct_window* w;
 
     // Check if the confirm window already exists.
-    w = window_bring_to_front_by_number(WC_FIRE_PROMPT, peep->sprite_index);
+    w = window_bring_to_front_by_number(WC_FIRE_PROMPT, peep->sprite_index.ToUnderlying());
     if (w != nullptr)
     {
         return w;
@@ -67,7 +67,7 @@ rct_window* WindowStaffFirePromptOpen(Peep* peep)
 
     WindowInitScrollWidgets(w);
 
-    w->number = peep->sprite_index;
+    w->number = peep->sprite_index.ToUnderlying();
 
     return w;
 }
@@ -82,7 +82,7 @@ static void WindowStaffFireMouseup(rct_window* w, rct_widgetindex widgetIndex)
     {
         case WIDX_YES:
         {
-            auto staffFireAction = StaffFireAction(w->number);
+            auto staffFireAction = StaffFireAction(EntityId::FromUnderlying(w->number));
             GameActions::Execute(&staffFireAction);
             break;
         }
@@ -100,7 +100,7 @@ static void WindowStaffFirePaint(rct_window* w, rct_drawpixelinfo* dpi)
 {
     WindowDrawWidgets(w, dpi);
 
-    Peep* peep = GetEntity<Staff>(w->number);
+    Peep* peep = GetEntity<Staff>(EntityId::FromUnderlying(w->number));
     auto ft = Formatter();
     peep->FormatNameTo(ft);
 
diff --git a/src/openrct2-ui/windows/StaffList.cpp b/src/openrct2-ui/windows/StaffList.cpp
index d344de3a1b..a0e9801d58 100644
--- a/src/openrct2-ui/windows/StaffList.cpp
+++ b/src/openrct2-ui/windows/StaffList.cpp
@@ -93,7 +93,7 @@ private:
         rct_string_id ActionHire;
     };
 
-    std::vector<uint16_t> _staffList;
+    std::vector<EntityId> _staffList;
     bool _quickFireMode{};
     std::optional<size_t> _highlightedIndex{};
     int32_t _selectedTab{};
@@ -490,8 +490,7 @@ public:
             }
         }
 
-        std::sort(
-            _staffList.begin(), _staffList.end(), [](const uint16_t a, const uint16_t b) { return peep_compare(a, b) < 0; });
+        std::sort(_staffList.begin(), _staffList.end(), [](const auto a, const auto b) { return peep_compare(a, b) < 0; });
     }
 
 private:
diff --git a/src/openrct2-ui/windows/TitleCommandEditor.cpp b/src/openrct2-ui/windows/TitleCommandEditor.cpp
index de32970cb4..aecd027a80 100644
--- a/src/openrct2-ui/windows/TitleCommandEditor.cpp
+++ b/src/openrct2-ui/windows/TitleCommandEditor.cpp
@@ -254,9 +254,9 @@ void WindowTitleCommandEditorOpen(TitleSequence* sequence, int32_t index, bool i
             snprintf(textbox1Buffer, BUF_SIZE, "%d", _command.Milliseconds);
             break;
         case TitleScript::Follow:
-            if (_command.SpriteIndex != SPRITE_INDEX_NULL)
+            if (!_command.SpriteIndex.IsNull())
             {
-                window_follow_sprite(window, static_cast<size_t>(_command.SpriteIndex));
+                window_follow_sprite(window, _command.SpriteIndex);
             }
             break;
         case TitleScript::Undefined:
@@ -432,7 +432,7 @@ static void WindowTitleCommandEditorDropdown(rct_window* w, rct_widgetindex widg
     switch (widgetIndex)
     {
         case WIDX_COMMAND_DROPDOWN:
-            if (_command.SpriteIndex != SPRITE_INDEX_NULL)
+            if (!_command.SpriteIndex.IsNull())
             {
                 window_unfollow_sprite(w);
             }
@@ -471,7 +471,7 @@ static void WindowTitleCommandEditorDropdown(rct_window* w, rct_widgetindex widg
                     snprintf(textbox1Buffer, BUF_SIZE, "%d", _command.Zoom);
                     break;
                 case TitleScript::Follow:
-                    _command.SpriteIndex = SPRITE_INDEX_NULL;
+                    _command.SpriteIndex = EntityId::GetNull();
                     _command.SpriteName[0] = '\0';
                     window_unfollow_sprite(w);
                     // This is incorrect
@@ -680,7 +680,7 @@ static void WindowTitleCommandEditorToolDown(rct_window* w, rct_widgetindex widg
         if (validSprite)
         {
             _command.SpriteIndex = entity->sprite_index;
-            window_follow_sprite(w, static_cast<size_t>(_command.SpriteIndex));
+            window_follow_sprite(w, _command.SpriteIndex);
             tool_cancel();
             w->Invalidate();
         }
@@ -790,7 +790,7 @@ static void WindowTitleCommandEditorPaint(rct_window* w, rct_drawpixelinfo* dpi)
         uint8_t colour = COLOUR_BLACK;
         rct_string_id spriteString = STR_TITLE_COMMAND_EDITOR_FORMAT_SPRITE_NAME;
         auto ft = Formatter();
-        if (_command.SpriteIndex != SPRITE_INDEX_NULL)
+        if (!_command.SpriteIndex.IsNull())
         {
             window_draw_viewport(dpi, w);
             ft.Add<utf8*>(_command.SpriteName);
diff --git a/src/openrct2-ui/windows/TitleEditor.cpp b/src/openrct2-ui/windows/TitleEditor.cpp
index 5c08636095..a1c0ced3d3 100644
--- a/src/openrct2-ui/windows/TitleEditor.cpp
+++ b/src/openrct2-ui/windows/TitleEditor.cpp
@@ -974,7 +974,7 @@ static void WindowTitleEditorScrollpaintCommands(rct_window* w, rct_drawpixelinf
             case TitleScript::Follow:
             {
                 auto commandName = STR_TITLE_EDITOR_COMMAND_FOLLOW;
-                if (command.SpriteIndex == SPRITE_INDEX_NULL)
+                if (command.SpriteIndex.IsNull())
                 {
                     commandName = STR_TITLE_EDITOR_COMMAND_FOLLOW_NO_SPRITE;
                     ft.Add<rct_string_id>(commandName);
diff --git a/src/openrct2/Game.cpp b/src/openrct2/Game.cpp
index bd6d81532d..6b8edd06b6 100644
--- a/src/openrct2/Game.cpp
+++ b/src/openrct2/Game.cpp
@@ -521,7 +521,7 @@ void reset_all_sprite_quadrant_placements()
 {
     for (size_t i = 0; i < MAX_ENTITIES; i++)
     {
-        auto* spr = GetEntity(i);
+        auto* spr = GetEntity(EntityId::FromUnderlying(i));
         if (spr != nullptr && spr->Type != EntityType::Null)
         {
             spr->MoveTo(spr->GetLocation());
diff --git a/src/openrct2/GameStateSnapshots.cpp b/src/openrct2/GameStateSnapshots.cpp
index 8a93b07aa9..1cd7e1cae8 100644
--- a/src/openrct2/GameStateSnapshots.cpp
+++ b/src/openrct2/GameStateSnapshots.cpp
@@ -69,7 +69,7 @@ struct GameStateSnapshot_t
     }
 
     // Must pass a function that can access the sprite.
-    void SerialiseSprites(std::function<EntitySnapshot*(const size_t)> getEntity, const size_t numSprites, bool saving)
+    void SerialiseSprites(std::function<EntitySnapshot*(const EntityId)> getEntity, const size_t numSprites, bool saving)
     {
         const bool loading = !saving;
 
@@ -85,7 +85,7 @@ struct GameStateSnapshot_t
         {
             for (size_t i = 0; i < numSprites; i++)
             {
-                auto entity = getEntity(i);
+                auto entity = getEntity(EntityId::FromUnderlying(i));
                 if (entity == nullptr || entity->base.Type == EntityType::Null)
                     continue;
                 indexTable.push_back(static_cast<uint32_t>(i));
@@ -111,7 +111,7 @@ struct GameStateSnapshot_t
         {
             ds << indexTable[i];
 
-            const uint32_t spriteIdx = indexTable[i];
+            const EntityId spriteIdx = EntityId::FromUnderlying(indexTable[i]);
             EntitySnapshot* entity = getEntity(spriteIdx);
             if (entity == nullptr)
             {
@@ -184,7 +184,7 @@ struct GameStateSnapshots final : public IGameStateSnapshots
     virtual void Capture(GameStateSnapshot_t& snapshot) override final
     {
         snapshot.SerialiseSprites(
-            [](const size_t index) { return reinterpret_cast<EntitySnapshot*>(GetEntity(index)); }, MAX_ENTITIES, true);
+            [](const EntityId index) { return reinterpret_cast<EntitySnapshot*>(GetEntity(index)); }, MAX_ENTITIES, true);
 
         // log_info("Snapshot size: %u bytes", static_cast<uint32_t>(snapshot.storedSprites.GetLength()));
     }
@@ -218,7 +218,7 @@ struct GameStateSnapshots final : public IGameStateSnapshots
             sprite.base.Type = EntityType::Null;
         }
 
-        snapshot.SerialiseSprites([&spriteList](const size_t index) { return &spriteList[index]; }, MAX_ENTITIES, false);
+        snapshot.SerialiseSprites([&spriteList](const EntityId index) { return &spriteList[index.ToUnderlying()]; }, MAX_ENTITIES, false);
 
         return spriteList;
     }
diff --git a/src/openrct2/Identifiers.h b/src/openrct2/Identifiers.h
index 53e5eb4c3b..e33a8f38f8 100644
--- a/src/openrct2/Identifiers.h
+++ b/src/openrct2/Identifiers.h
@@ -19,3 +19,5 @@ using ParkEntranceIndex = TIdentifier<uint8_t, std::numeric_limits<uint8_t>::max
 using BannerIndex = TIdentifier<uint16_t, std::numeric_limits<uint16_t>::max(), struct BannerIndexTag>;
 
 using RideId = TIdentifier<uint16_t, std::numeric_limits<uint16_t>::max(), struct RideIdTag>;
+
+using EntityId = TIdentifier<uint64_t, std::numeric_limits<uint16_t>::max(), struct EntityIdTag>;
diff --git a/src/openrct2/actions/BalloonPressAction.cpp b/src/openrct2/actions/BalloonPressAction.cpp
index 13e9c82215..a7bf53aedd 100644
--- a/src/openrct2/actions/BalloonPressAction.cpp
+++ b/src/openrct2/actions/BalloonPressAction.cpp
@@ -13,7 +13,7 @@
 #include "../entity/EntityRegistry.h"
 #include "GameAction.h"
 
-BalloonPressAction::BalloonPressAction(uint16_t spriteIndex)
+BalloonPressAction::BalloonPressAction(EntityId spriteIndex)
     : _spriteIndex(spriteIndex)
 {
 }
diff --git a/src/openrct2/actions/BalloonPressAction.h b/src/openrct2/actions/BalloonPressAction.h
index 6e126b3c3c..953b3b30fd 100644
--- a/src/openrct2/actions/BalloonPressAction.h
+++ b/src/openrct2/actions/BalloonPressAction.h
@@ -9,15 +9,16 @@
 
 #pragma once
 
+#include "../Identifiers.h"
 #include "GameAction.h"
 
 class BalloonPressAction final : public GameActionBase<GameCommand::BalloonPress>
 {
-    uint16_t _spriteIndex{ SPRITE_INDEX_NULL };
+    EntityId _spriteIndex{ EntityId::GetNull() };
 
 public:
     BalloonPressAction() = default;
-    BalloonPressAction(uint16_t spriteIndex);
+    BalloonPressAction(EntityId spriteIndex);
 
     void AcceptParameters(GameActionParameterVisitor& visitor) override;
 
diff --git a/src/openrct2/actions/GameActionCompat.cpp b/src/openrct2/actions/GameActionCompat.cpp
index 2ccb75cad0..02b3e69713 100644
--- a/src/openrct2/actions/GameActionCompat.cpp
+++ b/src/openrct2/actions/GameActionCompat.cpp
@@ -110,7 +110,7 @@ void ride_action_modify(Ride* ride, int32_t modifyType, int32_t flags)
 
 #pragma region GuestSetName
 
-void guest_set_name(uint16_t spriteIndex, const char* name)
+void guest_set_name(EntityId spriteIndex, const char* name)
 {
     auto gameAction = GuestSetNameAction(spriteIndex, name);
     GameActions::Execute(&gameAction);
diff --git a/src/openrct2/actions/GuestSetFlagsAction.cpp b/src/openrct2/actions/GuestSetFlagsAction.cpp
index d3fd1747a3..9366812d38 100644
--- a/src/openrct2/actions/GuestSetFlagsAction.cpp
+++ b/src/openrct2/actions/GuestSetFlagsAction.cpp
@@ -13,7 +13,7 @@
 #include "../OpenRCT2.h"
 #include "../entity/EntityRegistry.h"
 
-GuestSetFlagsAction::GuestSetFlagsAction(uint16_t peepId, uint32_t flags)
+GuestSetFlagsAction::GuestSetFlagsAction(EntityId peepId, uint32_t flags)
     : _peepId(peepId)
     , _newFlags(flags)
 {
@@ -42,7 +42,7 @@ GameActions::Result GuestSetFlagsAction::Query() const
     auto* peep = TryGetEntity<Guest>(_peepId);
     if (peep == nullptr)
     {
-        log_error("Used invalid sprite index for peep: %u", static_cast<uint32_t>(_peepId));
+        log_error("Used invalid sprite index for peep: %u", _peepId.ToUnderlying());
         return GameActions::Result(GameActions::Status::InvalidParameters, STR_CANT_CHANGE_THIS, STR_NONE);
     }
     return GameActions::Result();
@@ -53,7 +53,7 @@ GameActions::Result GuestSetFlagsAction::Execute() const
     auto* peep = TryGetEntity<Guest>(_peepId);
     if (peep == nullptr)
     {
-        log_error("Used invalid sprite index for peep: %u", static_cast<uint32_t>(_peepId));
+        log_error("Used invalid sprite index for peep: %u", _peepId.ToUnderlying());
         return GameActions::Result(GameActions::Status::InvalidParameters, STR_CANT_CHANGE_THIS, STR_NONE);
     }
 
diff --git a/src/openrct2/actions/GuestSetFlagsAction.h b/src/openrct2/actions/GuestSetFlagsAction.h
index 9cc5b4384f..1bfc75493f 100644
--- a/src/openrct2/actions/GuestSetFlagsAction.h
+++ b/src/openrct2/actions/GuestSetFlagsAction.h
@@ -14,12 +14,12 @@
 class GuestSetFlagsAction final : public GameActionBase<GameCommand::GuestSetFlags>
 {
 private:
-    uint16_t _peepId{ SPRITE_INDEX_NULL };
+    EntityId _peepId{ EntityId::GetNull() };
     uint32_t _newFlags{};
 
 public:
     GuestSetFlagsAction() = default;
-    GuestSetFlagsAction(uint16_t peepId, uint32_t flags);
+    GuestSetFlagsAction(EntityId peepId, uint32_t flags);
 
     void AcceptParameters(GameActionParameterVisitor& visitor) override;
 
diff --git a/src/openrct2/actions/GuestSetNameAction.cpp b/src/openrct2/actions/GuestSetNameAction.cpp
index 2dfdf1ea5d..fd5e4e70a4 100644
--- a/src/openrct2/actions/GuestSetNameAction.cpp
+++ b/src/openrct2/actions/GuestSetNameAction.cpp
@@ -20,13 +20,13 @@
 #include "../windows/Intent.h"
 #include "../world/Park.h"
 
-GuestSetNameAction::GuestSetNameAction(uint16_t spriteIndex, const std::string& name)
+GuestSetNameAction::GuestSetNameAction(EntityId spriteIndex, const std::string& name)
     : _spriteIndex(spriteIndex)
     , _name(name)
 {
 }
 
-uint16_t GuestSetNameAction::GetSpriteIndex() const
+EntityId GuestSetNameAction::GetSpriteIndex() const
 {
     return _spriteIndex;
 }
@@ -56,7 +56,7 @@ void GuestSetNameAction::Serialise(DataSerialiser& stream)
 
 GameActions::Result GuestSetNameAction::Query() const
 {
-    if (_spriteIndex >= MAX_ENTITIES)
+    if (_spriteIndex.ToUnderlying() >= MAX_ENTITIES || _spriteIndex.IsNull())
     {
         return GameActions::Result(GameActions::Status::InvalidParameters, STR_CANT_NAME_GUEST, STR_NONE);
     }
diff --git a/src/openrct2/actions/GuestSetNameAction.h b/src/openrct2/actions/GuestSetNameAction.h
index 347bc6b079..a1ca8f485f 100644
--- a/src/openrct2/actions/GuestSetNameAction.h
+++ b/src/openrct2/actions/GuestSetNameAction.h
@@ -14,14 +14,14 @@
 class GuestSetNameAction final : public GameActionBase<GameCommand::SetGuestName>
 {
 private:
-    uint16_t _spriteIndex{ SPRITE_INDEX_NULL };
+    EntityId _spriteIndex{ EntityId::GetNull() };
     std::string _name;
 
 public:
     GuestSetNameAction() = default;
-    GuestSetNameAction(uint16_t spriteIndex, const std::string& name);
+    GuestSetNameAction(EntityId spriteIndex, const std::string& name);
 
-    uint16_t GetSpriteIndex() const;
+    EntityId GetSpriteIndex() const;
     std::string GetGuestName() const;
 
     void AcceptParameters(GameActionParameterVisitor& visitor) override;
diff --git a/src/openrct2/actions/PeepPickupAction.cpp b/src/openrct2/actions/PeepPickupAction.cpp
index 27f134b530..80b3916661 100644
--- a/src/openrct2/actions/PeepPickupAction.cpp
+++ b/src/openrct2/actions/PeepPickupAction.cpp
@@ -15,7 +15,7 @@
 #include "../network/network.h"
 #include "../util/Util.h"
 
-PeepPickupAction::PeepPickupAction(PeepPickupType type, uint32_t spriteId, const CoordsXYZ& loc, NetworkPlayerId_t owner)
+PeepPickupAction::PeepPickupAction(PeepPickupType type, EntityId spriteId, const CoordsXYZ& loc, NetworkPlayerId_t owner)
     : _type(type)
     , _spriteId(spriteId)
     , _loc(loc)
@@ -37,7 +37,7 @@ void PeepPickupAction::Serialise(DataSerialiser& stream)
 
 GameActions::Result PeepPickupAction::Query() const
 {
-    if (_spriteId >= MAX_ENTITIES || _spriteId == SPRITE_INDEX_NULL)
+    if (_spriteId.IsNull())
     {
         log_error("Failed to pick up peep for sprite %d", _spriteId);
         return GameActions::Result(GameActions::Status::InvalidParameters, STR_ERR_CANT_PLACE_PERSON_HERE, STR_NONE);
diff --git a/src/openrct2/actions/PeepPickupAction.h b/src/openrct2/actions/PeepPickupAction.h
index 3dc6dbfd16..edb777a848 100644
--- a/src/openrct2/actions/PeepPickupAction.h
+++ b/src/openrct2/actions/PeepPickupAction.h
@@ -9,6 +9,7 @@
 
 #pragma once
 
+#include "../Identifiers.h"
 #include "GameAction.h"
 
 enum class PeepPickupType : uint8_t
@@ -23,13 +24,13 @@ class PeepPickupAction final : public GameActionBase<GameCommand::PickupGuest>
 {
 private:
     PeepPickupType _type{ PeepPickupType::Count };
-    uint32_t _spriteId{ SPRITE_INDEX_NULL };
+    EntityId _spriteId{ EntityId::GetNull() };
     CoordsXYZ _loc;
     NetworkPlayerId_t _owner{ -1 };
 
 public:
     PeepPickupAction() = default;
-    PeepPickupAction(PeepPickupType type, uint32_t spriteId, const CoordsXYZ& loc, NetworkPlayerId_t owner);
+    PeepPickupAction(PeepPickupType type, EntityId spriteId, const CoordsXYZ& loc, NetworkPlayerId_t owner);
 
     uint16_t GetActionFlags() const override;
 
diff --git a/src/openrct2/actions/RideCreateAction.cpp b/src/openrct2/actions/RideCreateAction.cpp
index 0ebdf369d7..3cd2d40b1f 100644
--- a/src/openrct2/actions/RideCreateAction.cpp
+++ b/src/openrct2/actions/RideCreateAction.cpp
@@ -147,10 +147,7 @@ GameActions::Result RideCreateAction::Execute() const
         ride->stations[i].QueueTime = 0;
     }
 
-    for (auto& vehicle : ride->vehicles)
-    {
-        vehicle = SPRITE_INDEX_NULL;
-    }
+    std::fill(std::begin(ride->vehicles), std::end(ride->vehicles), EntityId::GetNull());
 
     ride->status = RideStatus::Closed;
     ride->lifecycle_flags = 0;
diff --git a/src/openrct2/actions/RideEntranceExitPlaceAction.cpp b/src/openrct2/actions/RideEntranceExitPlaceAction.cpp
index 6c5da7146b..45a9501690 100644
--- a/src/openrct2/actions/RideEntranceExitPlaceAction.cpp
+++ b/src/openrct2/actions/RideEntranceExitPlaceAction.cpp
@@ -196,7 +196,7 @@ GameActions::Result RideEntranceExitPlaceAction::Execute() const
     else
     {
         ride_set_entrance_location(ride, _stationNum, TileCoordsXYZD(CoordsXYZD{ _loc, z, entranceElement->GetDirection() }));
-        ride->stations[_stationNum].LastPeepInQueue = SPRITE_INDEX_NULL;
+        ride->stations[_stationNum].LastPeepInQueue = EntityId::GetNull();
         ride->stations[_stationNum].QueueLength = 0;
 
         map_animation_create(MAP_ANIMATION_TYPE_RIDE_ENTRANCE, { _loc, z });
diff --git a/src/openrct2/actions/RideSetStatusAction.cpp b/src/openrct2/actions/RideSetStatusAction.cpp
index 6892bba763..ce0c49515e 100644
--- a/src/openrct2/actions/RideSetStatusAction.cpp
+++ b/src/openrct2/actions/RideSetStatusAction.cpp
@@ -154,7 +154,7 @@ GameActions::Result RideSetStatusAction::Execute() const
 
             ride->status = RideStatus::Closed;
             ride->lifecycle_flags &= ~RIDE_LIFECYCLE_PASS_STATION_NO_STOPPING;
-            ride->race_winner = SPRITE_INDEX_NULL;
+            ride->race_winner = EntityId::GetNull();
             ride->window_invalidate_flags |= RIDE_INVALIDATE_RIDE_MAIN | RIDE_INVALIDATE_RIDE_LIST;
             window_invalidate_by_number(WC_RIDE, _rideIndex.ToUnderlying());
             break;
@@ -173,7 +173,7 @@ GameActions::Result RideSetStatusAction::Execute() const
 
             ride->status = _status;
             ride->lifecycle_flags &= ~RIDE_LIFECYCLE_PASS_STATION_NO_STOPPING;
-            ride->race_winner = SPRITE_INDEX_NULL;
+            ride->race_winner = EntityId::GetNull();
             ride->current_issues = 0;
             ride->last_issue_time = 0;
             ride->GetMeasurement();
@@ -219,7 +219,7 @@ GameActions::Result RideSetStatusAction::Execute() const
                 return res;
             }
 
-            ride->race_winner = SPRITE_INDEX_NULL;
+            ride->race_winner = EntityId::GetNull();
             ride->status = _status;
             ride->current_issues = 0;
             ride->last_issue_time = 0;
diff --git a/src/openrct2/actions/SetCheatAction.cpp b/src/openrct2/actions/SetCheatAction.cpp
index 8719fb552c..cad95b5da3 100644
--- a/src/openrct2/actions/SetCheatAction.cpp
+++ b/src/openrct2/actions/SetCheatAction.cpp
@@ -633,7 +633,7 @@ void SetCheatAction::RemoveAllGuests() const
         for (size_t stationIndex = 0; stationIndex < OpenRCT2::Limits::MaxStationsPerRide; stationIndex++)
         {
             ride.stations[stationIndex].QueueLength = 0;
-            ride.stations[stationIndex].LastPeepInQueue = SPRITE_INDEX_NULL;
+            ride.stations[stationIndex].LastPeepInQueue = EntityId::GetNull();
         }
 
         for (auto trainIndex : ride.vehicles)
@@ -652,7 +652,7 @@ void SetCheatAction::RemoveAllGuests() const
                             vehicle->ApplyMass(-peep->Mass);
                         }
                     }
-                    peepInTrainIndex = SPRITE_INDEX_NULL;
+                    peepInTrainIndex = EntityId::GetNull();
                 }
 
                 vehicle->num_peeps = 0;
diff --git a/src/openrct2/actions/StaffFireAction.cpp b/src/openrct2/actions/StaffFireAction.cpp
index b53436fbba..6abe354781 100644
--- a/src/openrct2/actions/StaffFireAction.cpp
+++ b/src/openrct2/actions/StaffFireAction.cpp
@@ -13,7 +13,7 @@
 #include "../entity/Staff.h"
 #include "../interface/Window.h"
 
-StaffFireAction::StaffFireAction(uint16_t spriteId)
+StaffFireAction::StaffFireAction(EntityId spriteId)
     : _spriteId(spriteId)
 {
 }
@@ -31,7 +31,7 @@ void StaffFireAction::Serialise(DataSerialiser& stream)
 
 GameActions::Result StaffFireAction::Query() const
 {
-    if (_spriteId >= MAX_ENTITIES)
+    if (_spriteId.ToUnderlying() >= MAX_ENTITIES || _spriteId.IsNull())
     {
         log_error("Invalid spriteId. spriteId = %u", _spriteId);
         return GameActions::Result(GameActions::Status::InvalidParameters, STR_NONE, STR_NONE);
diff --git a/src/openrct2/actions/StaffFireAction.h b/src/openrct2/actions/StaffFireAction.h
index 7caebf323e..2869f314ae 100644
--- a/src/openrct2/actions/StaffFireAction.h
+++ b/src/openrct2/actions/StaffFireAction.h
@@ -14,11 +14,11 @@
 class StaffFireAction final : public GameActionBase<GameCommand::FireStaffMember>
 {
 private:
-    uint16_t _spriteId{ SPRITE_INDEX_NULL };
+    EntityId _spriteId{ EntityId::GetNull() };
 
 public:
     StaffFireAction() = default;
-    StaffFireAction(uint16_t spriteId);
+    StaffFireAction(EntityId spriteId);
 
     uint16_t GetActionFlags() const override;
 
diff --git a/src/openrct2/actions/StaffHireNewAction.cpp b/src/openrct2/actions/StaffHireNewAction.cpp
index 51f33f051f..319265d73a 100644
--- a/src/openrct2/actions/StaffHireNewAction.cpp
+++ b/src/openrct2/actions/StaffHireNewAction.cpp
@@ -123,7 +123,7 @@ GameActions::Result StaffHireNewAction::QueryExecute(bool execute) const
         // In query we just want to see if we can obtain a sprite slot.
         EntityRemove(newPeep);
 
-        res.SetData(StaffHireNewActionResult{ SPRITE_INDEX_NULL });
+        res.SetData(StaffHireNewActionResult{ EntityId::GetNull() });
     }
     else
     {
diff --git a/src/openrct2/actions/StaffHireNewAction.h b/src/openrct2/actions/StaffHireNewAction.h
index 6a78407c39..84ef323e5a 100644
--- a/src/openrct2/actions/StaffHireNewAction.h
+++ b/src/openrct2/actions/StaffHireNewAction.h
@@ -14,7 +14,7 @@
 
 struct StaffHireNewActionResult
 {
-    uint16_t StaffEntityId = SPRITE_INDEX_NULL;
+    EntityId StaffEntityId = EntityId::GetNull();
 };
 
 class StaffHireNewAction final : public GameActionBase<GameCommand::HireNewStaffMember>
diff --git a/src/openrct2/actions/StaffSetCostumeAction.cpp b/src/openrct2/actions/StaffSetCostumeAction.cpp
index 294339695c..2944981c02 100644
--- a/src/openrct2/actions/StaffSetCostumeAction.cpp
+++ b/src/openrct2/actions/StaffSetCostumeAction.cpp
@@ -36,7 +36,7 @@ constexpr const bool peep_slow_walking_types[] = {
     true,  // PeepSpriteType::Balloon
 };
 
-StaffSetCostumeAction::StaffSetCostumeAction(uint16_t spriteIndex, EntertainerCostume costume)
+StaffSetCostumeAction::StaffSetCostumeAction(EntityId spriteIndex, EntertainerCostume costume)
     : _spriteIndex(spriteIndex)
     , _costume(costume)
 {
@@ -56,7 +56,7 @@ void StaffSetCostumeAction::Serialise(DataSerialiser& stream)
 
 GameActions::Result StaffSetCostumeAction::Query() const
 {
-    if (_spriteIndex >= MAX_ENTITIES)
+    if (_spriteIndex.ToUnderlying() >= MAX_ENTITIES || _spriteIndex.IsNull())
     {
         return GameActions::Result(GameActions::Status::InvalidParameters, STR_NONE, STR_NONE);
     }
diff --git a/src/openrct2/actions/StaffSetCostumeAction.h b/src/openrct2/actions/StaffSetCostumeAction.h
index f9f47c8cc2..823737abc2 100644
--- a/src/openrct2/actions/StaffSetCostumeAction.h
+++ b/src/openrct2/actions/StaffSetCostumeAction.h
@@ -15,12 +15,12 @@
 class StaffSetCostumeAction final : public GameActionBase<GameCommand::SetStaffCostume>
 {
 private:
-    uint16_t _spriteIndex{ SPRITE_INDEX_NULL };
+    EntityId _spriteIndex{ EntityId::GetNull() };
     EntertainerCostume _costume = EntertainerCostume::Count;
 
 public:
     StaffSetCostumeAction() = default;
-    StaffSetCostumeAction(uint16_t spriteIndex, EntertainerCostume costume);
+    StaffSetCostumeAction(EntityId spriteIndex, EntertainerCostume costume);
 
     uint16_t GetActionFlags() const override;
 
diff --git a/src/openrct2/actions/StaffSetNameAction.cpp b/src/openrct2/actions/StaffSetNameAction.cpp
index 33e21ad200..07f281b6fb 100644
--- a/src/openrct2/actions/StaffSetNameAction.cpp
+++ b/src/openrct2/actions/StaffSetNameAction.cpp
@@ -21,7 +21,7 @@
 #include "../windows/Intent.h"
 #include "../world/Park.h"
 
-StaffSetNameAction::StaffSetNameAction(uint16_t spriteIndex, const std::string& name)
+StaffSetNameAction::StaffSetNameAction(EntityId spriteIndex, const std::string& name)
     : _spriteIndex(spriteIndex)
     , _name(name)
 {
@@ -41,7 +41,7 @@ void StaffSetNameAction::Serialise(DataSerialiser& stream)
 
 GameActions::Result StaffSetNameAction::Query() const
 {
-    if (_spriteIndex >= MAX_ENTITIES)
+    if (_spriteIndex.ToUnderlying() >= MAX_ENTITIES || _spriteIndex.IsNull())
     {
         return GameActions::Result(GameActions::Status::InvalidParameters, STR_STAFF_ERROR_CANT_NAME_STAFF_MEMBER, STR_NONE);
     }
diff --git a/src/openrct2/actions/StaffSetNameAction.h b/src/openrct2/actions/StaffSetNameAction.h
index 7cf8804fa6..59ac9ad6ce 100644
--- a/src/openrct2/actions/StaffSetNameAction.h
+++ b/src/openrct2/actions/StaffSetNameAction.h
@@ -14,12 +14,12 @@
 class StaffSetNameAction final : public GameActionBase<GameCommand::SetStaffName>
 {
 private:
-    uint16_t _spriteIndex{ SPRITE_INDEX_NULL };
+    EntityId _spriteIndex{ EntityId::GetNull() };
     std::string _name;
 
 public:
     StaffSetNameAction() = default;
-    StaffSetNameAction(uint16_t spriteIndex, const std::string& name);
+    StaffSetNameAction(EntityId spriteIndex, const std::string& name);
 
     uint16_t GetActionFlags() const override;
     void Serialise(DataSerialiser& stream) override;
diff --git a/src/openrct2/actions/StaffSetOrdersAction.cpp b/src/openrct2/actions/StaffSetOrdersAction.cpp
index 8070041c77..2ed8b0b271 100644
--- a/src/openrct2/actions/StaffSetOrdersAction.cpp
+++ b/src/openrct2/actions/StaffSetOrdersAction.cpp
@@ -17,7 +17,7 @@
 #include "../localisation/StringIds.h"
 #include "../windows/Intent.h"
 
-StaffSetOrdersAction::StaffSetOrdersAction(uint16_t spriteIndex, uint8_t ordersId)
+StaffSetOrdersAction::StaffSetOrdersAction(EntityId spriteIndex, uint8_t ordersId)
     : _spriteIndex(spriteIndex)
     , _ordersId(ordersId)
 {
@@ -37,7 +37,7 @@ void StaffSetOrdersAction::Serialise(DataSerialiser& stream)
 
 GameActions::Result StaffSetOrdersAction::Query() const
 {
-    if (_spriteIndex >= MAX_ENTITIES)
+    if (_spriteIndex.ToUnderlying() >= MAX_ENTITIES || _spriteIndex.IsNull())
     {
         return GameActions::Result(GameActions::Status::InvalidParameters, STR_NONE, STR_NONE);
     }
diff --git a/src/openrct2/actions/StaffSetOrdersAction.h b/src/openrct2/actions/StaffSetOrdersAction.h
index 078d1eb82a..5d81ded28c 100644
--- a/src/openrct2/actions/StaffSetOrdersAction.h
+++ b/src/openrct2/actions/StaffSetOrdersAction.h
@@ -14,12 +14,12 @@
 class StaffSetOrdersAction final : public GameActionBase<GameCommand::SetStaffOrders>
 {
 private:
-    uint16_t _spriteIndex{ SPRITE_INDEX_NULL };
+    EntityId _spriteIndex{ EntityId::GetNull() };
     uint8_t _ordersId{};
 
 public:
     StaffSetOrdersAction() = default;
-    StaffSetOrdersAction(uint16_t spriteIndex, uint8_t ordersId);
+    StaffSetOrdersAction(EntityId spriteIndex, uint8_t ordersId);
 
     uint16_t GetActionFlags() const override;
 
diff --git a/src/openrct2/actions/StaffSetPatrolAreaAction.cpp b/src/openrct2/actions/StaffSetPatrolAreaAction.cpp
index c95503da85..ad2aa456cd 100644
--- a/src/openrct2/actions/StaffSetPatrolAreaAction.cpp
+++ b/src/openrct2/actions/StaffSetPatrolAreaAction.cpp
@@ -14,7 +14,7 @@
 #include "../entity/Staff.h"
 #include "../interface/Window.h"
 
-StaffSetPatrolAreaAction::StaffSetPatrolAreaAction(uint16_t spriteId, const CoordsXY& loc, const StaffSetPatrolAreaMode mode)
+StaffSetPatrolAreaAction::StaffSetPatrolAreaAction(EntityId spriteId, const CoordsXY& loc, const StaffSetPatrolAreaMode mode)
     : _spriteId(spriteId)
     , _loc(loc)
     , _mode(mode)
@@ -34,7 +34,7 @@ void StaffSetPatrolAreaAction::Serialise(DataSerialiser& stream)
 
 GameActions::Result StaffSetPatrolAreaAction::Query() const
 {
-    if (_spriteId >= MAX_ENTITIES)
+    if (_spriteId.ToUnderlying() >= MAX_ENTITIES || _spriteId.IsNull())
     {
         log_error("Invalid spriteId. spriteId = %u", _spriteId);
         return GameActions::Result(GameActions::Status::InvalidParameters, STR_NONE, STR_NONE);
diff --git a/src/openrct2/actions/StaffSetPatrolAreaAction.h b/src/openrct2/actions/StaffSetPatrolAreaAction.h
index e18a851977..939f608a73 100644
--- a/src/openrct2/actions/StaffSetPatrolAreaAction.h
+++ b/src/openrct2/actions/StaffSetPatrolAreaAction.h
@@ -21,13 +21,13 @@ enum class StaffSetPatrolAreaMode : uint8_t
 class StaffSetPatrolAreaAction final : public GameActionBase<GameCommand::SetStaffPatrol>
 {
 private:
-    uint16_t _spriteId{ SPRITE_INDEX_NULL };
+    EntityId _spriteId{ EntityId::GetNull() };
     CoordsXY _loc;
     StaffSetPatrolAreaMode _mode;
 
 public:
     StaffSetPatrolAreaAction() = default;
-    StaffSetPatrolAreaAction(uint16_t spriteId, const CoordsXY& loc, const StaffSetPatrolAreaMode mode);
+    StaffSetPatrolAreaAction(EntityId spriteId, const CoordsXY& loc, const StaffSetPatrolAreaMode mode);
 
     uint16_t GetActionFlags() const override;
 
diff --git a/src/openrct2/audio/audio.h b/src/openrct2/audio/audio.h
index 8c05248d81..7480b0a2a8 100644
--- a/src/openrct2/audio/audio.h
+++ b/src/openrct2/audio/audio.h
@@ -9,6 +9,7 @@
 
 #pragma once
 
+#include "../Identifiers.h"
 #include "../common.h"
 #include "../ride/RideTypes.h"
 
diff --git a/src/openrct2/core/DataSerialiserTraits.h b/src/openrct2/core/DataSerialiserTraits.h
index 7916508cc6..4a6d86a9b9 100644
--- a/src/openrct2/core/DataSerialiserTraits.h
+++ b/src/openrct2/core/DataSerialiserTraits.h
@@ -329,6 +329,12 @@ template<size_t _Size> struct DataSerializerTraits_t<uint64_t[_Size]> : public D
 {
 };
 
+template<typename T, T TNullValue, typename TTag, typename size_t _Size>
+struct DataSerializerTraits_t<TIdentifier<T, TNullValue, TTag>[_Size]>
+    : public DataSerializerTraitsPODArray<TIdentifier<T, TNullValue, TTag>, _Size>
+{
+};
+
 template<typename _Ty, size_t _Size> struct DataSerializerTraits_t<std::array<_Ty, _Size>>
 {
     static void encode(OpenRCT2::IStream* stream, const std::array<_Ty, _Size>& val)
diff --git a/src/openrct2/core/GroupVector.hpp b/src/openrct2/core/GroupVector.hpp
index 195e669783..89157a7dc3 100644
--- a/src/openrct2/core/GroupVector.hpp
+++ b/src/openrct2/core/GroupVector.hpp
@@ -18,20 +18,22 @@ template<typename Handle, typename V> class GroupVector
 public:
     bool Contains(Handle handle, V value)
     {
-        if (handle >= _data.size())
+        const auto index = static_cast<std::size_t>(handle);
+        if (index >= _data.size())
             return false;
 
-        const auto& values = _data[handle];
+        const auto& values = _data[index];
         return std::find(values.begin(), values.end(), value) != values.end();
     }
 
     void Add(Handle handle, V value)
     {
-        if (handle >= _data.size())
+        const auto index = static_cast<std::size_t>(handle);
+        if (index >= _data.size())
         {
-            _data.resize(handle + 1);
+            _data.resize(index + 1);
         }
-        auto& values = _data[handle];
+        auto& values = _data[index];
 
         auto it = std::find(values.begin(), values.end(), value);
         if (it != values.end())
@@ -42,18 +44,20 @@ public:
 
     void Set(Handle handle, std::vector<V>&& values)
     {
-        if (handle >= _data.size())
+        const auto index = static_cast<std::size_t>(handle);
+        if (index >= _data.size())
         {
-            _data.resize(handle + 1);
+            _data.resize(index + 1);
         }
-        _data[handle] = values;
+        _data[index] = values;
     }
 
     std::vector<V>* GetAll(Handle handle)
     {
-        if (handle < _data.size())
+        const auto index = static_cast<std::size_t>(handle);
+        if (index < _data.size())
         {
-            return &_data[handle];
+            return &_data[index];
         }
         return nullptr;
     }
@@ -65,9 +69,10 @@ public:
 
     void RemoveHandle(Handle handle)
     {
-        if (handle < _data.size())
+        const auto index = static_cast<std::size_t>(handle);
+        if (index < _data.size())
         {
-            _data[handle].clear();
+            _data[index].clear();
         }
     }
 
diff --git a/src/openrct2/core/Identifier.hpp b/src/openrct2/core/Identifier.hpp
index 40be23d05e..540ebe58c1 100644
--- a/src/openrct2/core/Identifier.hpp
+++ b/src/openrct2/core/Identifier.hpp
@@ -47,6 +47,12 @@ public:
         return static_cast<T>(_handle);
     }
 
+    // Support for static_cast<size_t>.
+    explicit operator std::size_t() const noexcept
+    {
+        return static_cast<std::size_t>(ToUnderlying());
+    }
+
     constexpr bool IsNull() const noexcept
     {
         return _handle == ValueType::Null;
@@ -71,4 +77,14 @@ public:
     {
         return _handle != other._handle;
     }
+
+    constexpr bool operator<(const TIdentifier& other) const noexcept
+    {
+        return ToUnderlying() < other.ToUnderlying();
+    }
+
+    constexpr bool operator>(const TIdentifier& other) const noexcept
+    {
+        return ToUnderlying() > other.ToUnderlying();
+    }
 };
diff --git a/src/openrct2/drawing/LightFX.cpp b/src/openrct2/drawing/LightFX.cpp
index 699959e918..8882aef305 100644
--- a/src/openrct2/drawing/LightFX.cpp
+++ b/src/openrct2/drawing/LightFX.cpp
@@ -677,7 +677,7 @@ static void LightfxAdd3DLight(const CoordsXYZ& loc, const LightType lightType)
 
 void LightfxAdd3DLight(const EntityBase& entity, const uint8_t id, const CoordsXYZ& loc, const LightType lightType)
 {
-    LightfxAdd3DLight(entity.sprite_index, LightFXQualifier::Entity, id, loc, lightType);
+    LightfxAdd3DLight(entity.sprite_index.ToUnderlying(), LightFXQualifier::Entity, id, loc, lightType);
 }
 
 void lightfx_add_3d_light_magic_from_drawing_tile(
@@ -736,7 +736,7 @@ void lightfx_add_lights_magic_vehicle(const Vehicle* vehicle)
         case RIDE_TYPE_WATER_COASTER:
         {
             Vehicle* vehicle_draw = vehicle->TrainHead();
-            auto nextVeh = GetEntity<Vehicle>(vehicle_draw->next_vehicle_on_train);
+            auto* nextVeh = GetEntity<Vehicle>(vehicle_draw->next_vehicle_on_train);
             if (nextVeh != nullptr)
             {
                 vehicle_draw = nextVeh;
diff --git a/src/openrct2/entity/Balloon.cpp b/src/openrct2/entity/Balloon.cpp
index c5cc3403e9..d0cb58732e 100644
--- a/src/openrct2/entity/Balloon.cpp
+++ b/src/openrct2/entity/Balloon.cpp
@@ -65,7 +65,7 @@ void Balloon::Press()
         // There is a random chance that pressing the balloon will not pop it
         // and instead shift it slightly
         uint32_t random = scenario_rand();
-        if ((sprite_index & 7) || (random & 0xFFFF) < 0x2000)
+        if ((sprite_index.ToUnderlying() & 7) || (random & 0xFFFF) < 0x2000)
         {
             Pop();
         }
diff --git a/src/openrct2/entity/Duck.cpp b/src/openrct2/entity/Duck.cpp
index 96558c7317..ef834a3558 100644
--- a/src/openrct2/entity/Duck.cpp
+++ b/src/openrct2/entity/Duck.cpp
@@ -150,7 +150,7 @@ void Duck::UpdateFlyToWater()
 
 void Duck::UpdateSwim()
 {
-    if (((gCurrentTicks + sprite_index) & 3) != 0)
+    if (((gCurrentTicks + sprite_index.ToUnderlying()) & 3) != 0)
         return;
 
     uint32_t randomNumber = scenario_rand();
diff --git a/src/openrct2/entity/EntityBase.h b/src/openrct2/entity/EntityBase.h
index 04e6d6eec7..391f72d997 100644
--- a/src/openrct2/entity/EntityBase.h
+++ b/src/openrct2/entity/EntityBase.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "../Identifiers.h"
 #include "../common.h"
 #include "../world/Location.hpp"
 
@@ -25,7 +26,7 @@ enum class EntityType : uint8_t
 struct EntityBase
 {
     EntityType Type;
-    uint16_t sprite_index;
+    EntityId sprite_index;
     int32_t x;
     int32_t y;
     int32_t z;
diff --git a/src/openrct2/entity/EntityList.h b/src/openrct2/entity/EntityList.h
index ca181c6b34..2752dc2446 100644
--- a/src/openrct2/entity/EntityList.h
+++ b/src/openrct2/entity/EntityList.h
@@ -18,22 +18,22 @@
 #include <list>
 #include <vector>
 
-const std::list<uint16_t>& GetEntityList(const EntityType id);
+const std::list<EntityId>& GetEntityList(const EntityType id);
 
 uint16_t GetEntityListCount(EntityType list);
 uint16_t GetMiscEntityCount();
 uint16_t GetNumFreeEntities();
-const std::vector<uint16_t>& GetEntityTileList(const CoordsXY& spritePos);
+const std::vector<EntityId>& GetEntityTileList(const CoordsXY& spritePos);
 
 template<typename T> class EntityTileIterator
 {
 private:
-    std::vector<uint16_t>::const_iterator iter;
-    std::vector<uint16_t>::const_iterator end;
+    std::vector<EntityId>::const_iterator iter;
+    std::vector<EntityId>::const_iterator end;
     T* Entity = nullptr;
 
 public:
-    EntityTileIterator(std::vector<uint16_t>::const_iterator _iter, std::vector<uint16_t>::const_iterator _end)
+    EntityTileIterator(std::vector<EntityId>::const_iterator _iter, std::vector<EntityId>::const_iterator _end)
         : iter(_iter)
         , end(_end)
     {
@@ -79,7 +79,7 @@ public:
 template<typename T = EntityBase> class EntityTileList
 {
 private:
-    const std::vector<uint16_t>& vec;
+    const std::vector<EntityId>& vec;
 
 public:
     EntityTileList(const CoordsXY& loc)
@@ -100,12 +100,12 @@ public:
 template<typename T> class EntityListIterator
 {
 private:
-    std::list<uint16_t>::const_iterator iter;
-    std::list<uint16_t>::const_iterator end;
+    std::list<EntityId>::const_iterator iter;
+    std::list<EntityId>::const_iterator end;
     T* Entity = nullptr;
 
 public:
-    EntityListIterator(std::list<uint16_t>::const_iterator _iter, std::list<uint16_t>::const_iterator _end)
+    EntityListIterator(std::list<EntityId>::const_iterator _iter, std::list<EntityId>::const_iterator _end)
         : iter(_iter)
         , end(_end)
     {
@@ -152,7 +152,7 @@ template<typename T = EntityBase> class EntityList
 {
 private:
     using EntityListIterator_t = EntityListIterator<T>;
-    const std::list<uint16_t>& vec;
+    const std::list<EntityId>& vec;
 
 public:
     EntityList()
diff --git a/src/openrct2/entity/EntityRegistry.cpp b/src/openrct2/entity/EntityRegistry.cpp
index 4a93ade023..f8666d714b 100644
--- a/src/openrct2/entity/EntityRegistry.cpp
+++ b/src/openrct2/entity/EntityRegistry.cpp
@@ -46,15 +46,15 @@ union Entity
 };
 
 static Entity _entities[MAX_ENTITIES]{};
-static std::array<std::list<uint16_t>, EnumValue(EntityType::Count)> gEntityLists;
-static std::vector<uint16_t> _freeIdList;
+static std::array<std::list<EntityId>, EnumValue(EntityType::Count)> gEntityLists;
+static std::vector<EntityId> _freeIdList;
 
 static bool _entityFlashingList[MAX_ENTITIES];
 
 constexpr const uint32_t SPATIAL_INDEX_SIZE = (MAXIMUM_MAP_SIZE_TECHNICAL * MAXIMUM_MAP_SIZE_TECHNICAL) + 1;
 constexpr const uint32_t SPATIAL_INDEX_LOCATION_NULL = SPATIAL_INDEX_SIZE - 1;
 
-static std::array<std::vector<uint16_t>, SPATIAL_INDEX_SIZE> gEntitySpatialIndex;
+static std::array<std::vector<EntityId>, SPATIAL_INDEX_SIZE> gEntitySpatialIndex;
 
 static void FreeEntity(EntityBase& entity);
 
@@ -117,22 +117,23 @@ std::string EntitiesChecksum::ToString() const
     return result;
 }
 
-EntityBase* TryGetEntity(size_t entityIndex)
+EntityBase* TryGetEntity(EntityId entityIndex)
 {
-    return entityIndex >= MAX_ENTITIES ? nullptr : &_entities[entityIndex].base;
+    const auto idx = entityIndex.ToUnderlying();
+    return idx >= MAX_ENTITIES ? nullptr : &_entities[idx].base;
 }
 
-EntityBase* GetEntity(size_t entityIndex)
+EntityBase* GetEntity(EntityId entityIndex)
 {
-    if (entityIndex == SPRITE_INDEX_NULL)
+    if (entityIndex.IsNull())
     {
         return nullptr;
     }
-    openrct2_assert(entityIndex < MAX_ENTITIES, "Tried getting entity %u", entityIndex);
+    openrct2_assert(entityIndex.ToUnderlying() < MAX_ENTITIES, "Tried getting entity %u", entityIndex.ToUnderlying());
     return TryGetEntity(entityIndex);
 }
 
-const std::vector<uint16_t>& GetEntityTileList(const CoordsXY& spritePos)
+const std::vector<EntityId>& GetEntityTileList(const CoordsXY& spritePos)
 {
     return gEntitySpatialIndex[GetSpatialIndexOffset(spritePos)];
 }
@@ -148,13 +149,17 @@ static void ResetEntityLists()
 static void ResetFreeIds()
 {
     _freeIdList.clear();
-
     _freeIdList.resize(MAX_ENTITIES);
+
     // List needs to be back to front to simplify removing
-    std::iota(std::rbegin(_freeIdList), std::rend(_freeIdList), 0);
+    auto nextId = 0;
+    std::for_each(std::rbegin(_freeIdList), std::rend(_freeIdList), [&](auto& elem) {
+        elem = EntityId::FromUnderlying(nextId);
+        nextId++;
+    });
 }
 
-const std::list<uint16_t>& GetEntityList(const EntityType id)
+const std::list<EntityId>& GetEntityList(const EntityType id)
 {
     return gEntityLists[EnumValue(id)];
 }
@@ -170,7 +175,7 @@ void ResetAllEntities()
     // Free all associated Entity pointers prior to zeroing memory
     for (int32_t i = 0; i < MAX_ENTITIES; ++i)
     {
-        auto* spr = GetEntity(i);
+        auto* spr = GetEntity(EntityId::FromUnderlying(i));
         if (spr == nullptr)
         {
             continue;
@@ -183,13 +188,13 @@ void ResetAllEntities()
     OpenRCT2::RideUse::GetTypeHistory().Clear();
     for (int32_t i = 0; i < MAX_ENTITIES; ++i)
     {
-        auto* spr = GetEntity(i);
+        auto* spr = GetEntity(EntityId::FromUnderlying(i));
         if (spr == nullptr)
         {
             continue;
         }
         spr->Type = EntityType::Null;
-        spr->sprite_index = i;
+        spr->sprite_index = EntityId::FromUnderlying(i);
 
         _entityFlashingList[i] = false;
     }
@@ -214,7 +219,7 @@ void ResetEntitySpatialIndices()
     }
     for (size_t i = 0; i < MAX_ENTITIES; i++)
     {
-        auto* spr = GetEntity(i);
+        auto* spr = GetEntity(EntityId::FromUnderlying(i));
         if (spr != nullptr && spr->Type != EntityType::Null)
         {
             EntitySpatialInsert(spr, { spr->x, spr->y });
@@ -259,8 +264,8 @@ EntitiesChecksum GetAllEntitiesChecksum()
 static void EntityReset(EntityBase* entity)
 {
     // Need to retain how the sprite is linked in lists
-    uint16_t entityIndex = entity->sprite_index;
-    _entityFlashingList[entityIndex] = false;
+    auto entityIndex = entity->sprite_index;
+    _entityFlashingList[entityIndex.ToUnderlying()] = false;
 
     Entity* spr = reinterpret_cast<Entity*>(entity);
     *spr = Entity();
@@ -277,7 +282,7 @@ static void AddToEntityList(EntityBase* entity)
     list.insert(std::lower_bound(std::begin(list), std::end(list), entity->sprite_index), entity->sprite_index);
 }
 
-static void AddToFreeList(uint16_t index)
+static void AddToFreeList(EntityId index)
 {
     // Free list must be in reverse sprite_index order to prevent desync issues
     _freeIdList.insert(std::upper_bound(std::rbegin(_freeIdList), std::rend(_freeIdList), index).base(), index);
@@ -357,7 +362,7 @@ EntityBase* CreateEntity(EntityType type)
     return entity;
 }
 
-EntityBase* CreateEntityAt(const uint16_t index, const EntityType type)
+EntityBase* CreateEntityAt(const EntityId index, const EntityType type)
 {
     auto id = std::lower_bound(std::rbegin(_freeIdList), std::rend(_freeIdList), index);
     if (id == std::rend(_freeIdList) || *id != index)
@@ -544,12 +549,12 @@ uint16_t RemoveFloatingEntities()
 
 void EntitySetFlashing(EntityBase* entity, bool flashing)
 {
-    assert(entity->sprite_index < MAX_ENTITIES);
-    _entityFlashingList[entity->sprite_index] = flashing;
+    assert(entity->sprite_index.ToUnderlying() < MAX_ENTITIES);
+    _entityFlashingList[entity->sprite_index.ToUnderlying()] = flashing;
 }
 
 bool EntityGetFlashing(EntityBase* entity)
 {
-    assert(entity->sprite_index < MAX_ENTITIES);
-    return _entityFlashingList[entity->sprite_index];
+    assert(entity->sprite_index.ToUnderlying() < MAX_ENTITIES);
+    return _entityFlashingList[entity->sprite_index.ToUnderlying()];
 }
diff --git a/src/openrct2/entity/EntityRegistry.h b/src/openrct2/entity/EntityRegistry.h
index 458129ca26..8ae1f71ffa 100644
--- a/src/openrct2/entity/EntityRegistry.h
+++ b/src/openrct2/entity/EntityRegistry.h
@@ -16,17 +16,17 @@
 
 constexpr uint16_t MAX_ENTITIES = 65535;
 
-EntityBase* GetEntity(size_t sprite_idx);
+EntityBase* GetEntity(EntityId sprite_idx);
 
-template<typename T> T* GetEntity(size_t sprite_idx)
+template<typename T> T* GetEntity(EntityId sprite_idx)
 {
     auto spr = GetEntity(sprite_idx);
     return spr != nullptr ? spr->As<T>() : nullptr;
 }
 
-EntityBase* TryGetEntity(size_t spriteIndex);
+EntityBase* TryGetEntity(EntityId spriteIndex);
 
-template<typename T> T* TryGetEntity(size_t sprite_idx)
+template<typename T> T* TryGetEntity(EntityId sprite_idx)
 {
     auto spr = TryGetEntity(sprite_idx);
     return spr != nullptr ? spr->As<T>() : nullptr;
@@ -40,9 +40,9 @@ template<typename T> T* CreateEntity()
 }
 
 // Use only with imports that must happen at a specified index
-EntityBase* CreateEntityAt(const uint16_t index, const EntityType type);
+EntityBase* CreateEntityAt(const EntityId index, const EntityType type);
 // Use only with imports that must happen at a specified index
-template<typename T> T* CreateEntityAt(const uint16_t index)
+template<typename T> T* CreateEntityAt(const EntityId index)
 {
     return static_cast<T*>(CreateEntityAt(index, T::cEntityType));
 }
diff --git a/src/openrct2/entity/Guest.cpp b/src/openrct2/entity/Guest.cpp
index ff668e9dd3..9d44f7bfa7 100644
--- a/src/openrct2/entity/Guest.cpp
+++ b/src/openrct2/entity/Guest.cpp
@@ -1956,7 +1956,7 @@ bool Guest::ShouldGoOnRide(Ride* ride, int32_t entranceNum, bool atQueue, bool t
             // Rides without queues can only have one peep waiting at a time.
             if (!atQueue)
             {
-                if (ride->stations[entranceNum].LastPeepInQueue != SPRITE_INDEX_NULL)
+                if (!ride->stations[entranceNum].LastPeepInQueue.IsNull())
                 {
                     peep_tried_to_enter_full_queue(this, ride);
                     return false;
@@ -2549,7 +2549,7 @@ bool Guest::FindVehicleToEnter(Ride* ride, std::vector<uint8_t>& car_array)
 
     int32_t i = 0;
 
-    uint16_t vehicle_id = ride->vehicles[chosen_train];
+    auto vehicle_id = ride->vehicles[chosen_train];
     for (Vehicle* vehicle = GetEntity<Vehicle>(vehicle_id); vehicle != nullptr;
          vehicle = GetEntity<Vehicle>(vehicle->next_vehicle_on_train), ++i)
     {
@@ -2570,7 +2570,7 @@ bool Guest::FindVehicleToEnter(Ride* ride, std::vector<uint8_t>& car_array)
         if (ride->mode == RideMode::ForwardRotation || ride->mode == RideMode::BackwardRotation)
         {
             uint8_t position = (((~vehicle->Pitch + 1) >> 3) & 0xF) * 2;
-            if (vehicle->peep[position] != SPRITE_INDEX_NULL)
+            if (!vehicle->peep[position].IsNull())
                 continue;
         }
         car_array.push_back(i);
@@ -3982,7 +3982,7 @@ void Guest::UpdateRideFreeVehicleCheck()
     }
 
     vehicle->next_free_seat--;
-    vehicle->peep[CurrentSeat] = SPRITE_INDEX_NULL;
+    vehicle->peep[CurrentSeat] = EntityId::GetNull();
 
     peep_update_ride_no_free_vehicle_rejoin_queue(this, ride);
 }
@@ -5258,7 +5258,7 @@ void Guest::UpdateWalking()
     }
     else if (HasEmptyContainer())
     {
-        if ((!GetNextIsSurface()) && (static_cast<uint32_t>(sprite_index & 0x1FF) == (gCurrentTicks & 0x1FF))
+        if ((!GetNextIsSurface()) && (static_cast<uint32_t>(sprite_index.ToUnderlying() & 0x1FF) == (gCurrentTicks & 0x1FF))
             && ((0xFFFF & scenario_rand()) <= 4096))
         {
             int32_t container = bitscanforward(GetEmptyContainerFlags());
@@ -7127,7 +7127,7 @@ Guest* Guest::Generate(const CoordsXYZ& coords)
 
         // Create event args object
         auto obj = OpenRCT2::Scripting::DukObject(ctx);
-        obj.Set("id", peep->sprite_index);
+        obj.Set("id", peep->sprite_index.ToUnderlying());
 
         // Call the subscriptions
         auto e = obj.Take();
diff --git a/src/openrct2/entity/Guest.h b/src/openrct2/entity/Guest.h
index dcd7ea513e..59e01e2372 100644
--- a/src/openrct2/entity/Guest.h
+++ b/src/openrct2/entity/Guest.h
@@ -261,7 +261,7 @@ struct Guest : Peep
 
 public:
     uint8_t GuestNumRides;
-    uint16_t GuestNextInQueue;
+    EntityId GuestNextInQueue;
     int32_t ParkEntryTime;
     RideId GuestHeadingToRideId;
     uint8_t GuestIsLostCountdown;
@@ -465,7 +465,7 @@ extern uint8_t gGuestInitialThirst;
 
 extern uint32_t gNextGuestNumber;
 
-void guest_set_name(uint16_t spriteIndex, const char* name);
+void guest_set_name(EntityId spriteIndex, const char* name);
 
 void peep_thought_set_format_args(const PeepThought* thought, Formatter& ft);
 
diff --git a/src/openrct2/entity/Peep.cpp b/src/openrct2/entity/Peep.cpp
index 6c819d8728..6293f923b5 100644
--- a/src/openrct2/entity/Peep.cpp
+++ b/src/openrct2/entity/Peep.cpp
@@ -277,7 +277,7 @@ bool Peep::CheckForPath()
     PROFILED_FUNCTION();
 
     PathCheckOptimisation++;
-    if ((PathCheckOptimisation & 0xF) != (sprite_index & 0xF))
+    if ((PathCheckOptimisation & 0xF) != (sprite_index.ToUnderlying() & 0xF))
     {
         // This condition makes the check happen less often
         // As a side effect peeps hover for a short,
@@ -486,7 +486,7 @@ std::optional<CoordsXY> Peep::UpdateAction(int16_t& xy_distance)
     WindowInvalidateFlags |= PEEP_INVALIDATE_PEEP_2;
 
     const auto curLoc = GetLocation();
-    Litter::Create({ curLoc, sprite_direction }, (sprite_index & 1) ? Litter::Type::VomitAlt : Litter::Type::Vomit);
+    Litter::Create({ curLoc, sprite_direction }, (sprite_index.ToUnderlying() & 1) ? Litter::Type::VomitAlt : Litter::Type::Vomit);
 
     static constexpr OpenRCT2::Audio::SoundId coughs[4] = {
         OpenRCT2::Audio::SoundId::Cough1,
@@ -524,7 +524,7 @@ void peep_decrement_num_riders(Peep* peep)
  */
 void peep_window_state_update(Peep* peep)
 {
-    rct_window* w = window_find_by_number(WC_PEEP, peep->sprite_index);
+    rct_window* w = window_find_by_number(WC_PEEP, peep->sprite_index.ToUnderlying());
     if (w != nullptr)
         window_event_invalidate_call(w);
 
@@ -661,14 +661,14 @@ void peep_sprite_remove(Peep* peep)
     bool wasGuest = staff == nullptr;
     if (wasGuest)
     {
-        News::DisableNewsItems(News::ItemType::PeepOnRide, peep->sprite_index);
+        News::DisableNewsItems(News::ItemType::PeepOnRide, peep->sprite_index.ToUnderlying());
     }
     else
     {
         staff->ClearPatrolArea();
         staff_update_greyed_patrol_areas();
 
-        News::DisableNewsItems(News::ItemType::Peep, staff->sprite_index);
+        News::DisableNewsItems(News::ItemType::Peep, staff->sprite_index.ToUnderlying());
     }
     EntityRemove(peep);
 
@@ -1702,7 +1702,7 @@ static bool peep_interact_with_entrance(Peep* peep, const CoordsXYE& coords, uin
         guest->ActionSpriteImageOffset = _unk_F1AEF0;
         guest->InteractionRideIndex = rideIndex;
 
-        uint16_t previous_last = ride->stations[stationNum].LastPeepInQueue;
+        auto previous_last = ride->stations[stationNum].LastPeepInQueue;
         ride->stations[stationNum].LastPeepInQueue = guest->sprite_index;
         guest->GuestNextInQueue = previous_last;
         ride->stations[stationNum].QueueLength++;
@@ -2127,7 +2127,7 @@ static void peep_interact_with_path(Peep* peep, const CoordsXYE& coords)
                     guest->InteractionRideIndex = rideIndex;
 
                     // Add the peep to the ride queue.
-                    uint16_t old_last_peep = ride->stations[stationNum].LastPeepInQueue;
+                    auto old_last_peep = ride->stations[stationNum].LastPeepInQueue;
                     ride->stations[stationNum].LastPeepInQueue = guest->sprite_index;
                     guest->GuestNextInQueue = old_last_peep;
                     ride->stations[stationNum].QueueLength++;
@@ -2489,7 +2489,7 @@ rct_string_id get_real_name_string_id_from_id(uint32_t id)
     return dx;
 }
 
-int32_t peep_compare(const uint16_t sprite_index_a, const uint16_t sprite_index_b)
+int32_t peep_compare(const EntityId sprite_index_a, const EntityId sprite_index_b)
 {
     Peep const* peep_a = GetEntity<Peep>(sprite_index_a);
     Peep const* peep_b = GetEntity<Peep>(sprite_index_b);
diff --git a/src/openrct2/entity/Peep.h b/src/openrct2/entity/Peep.h
index 97087a0182..b59201fc70 100644
--- a/src/openrct2/entity/Peep.h
+++ b/src/openrct2/entity/Peep.h
@@ -473,7 +473,7 @@ void peep_window_state_update(Peep* peep);
 void peep_decrement_num_riders(Peep* peep);
 
 void peep_set_map_tooltip(Peep* peep);
-int32_t peep_compare(const uint16_t sprite_index_a, const uint16_t sprite_index_b);
+int32_t peep_compare(const EntityId sprite_index_a, const EntityId sprite_index_b);
 
 void peep_update_names(bool realNames);
 
diff --git a/src/openrct2/entity/Staff.cpp b/src/openrct2/entity/Staff.cpp
index 1e6f33409d..ced50d8cc0 100644
--- a/src/openrct2/entity/Staff.cpp
+++ b/src/openrct2/entity/Staff.cpp
@@ -551,7 +551,7 @@ bool Staff::DoHandymanPathFinding()
     Direction litterDirection = INVALID_DIRECTION;
     uint8_t validDirections = GetValidPatrolDirections(NextLoc);
 
-    if ((StaffOrders & STAFF_ORDERS_SWEEPING) && ((gCurrentTicks + sprite_index) & 0xFFF) > 110)
+    if ((StaffOrders & STAFF_ORDERS_SWEEPING) && ((gCurrentTicks + sprite_index.ToUnderlying()) & 0xFFF) > 110)
     {
         litterDirection = HandymanDirectionToNearestLitter();
     }
diff --git a/src/openrct2/interface/InteractiveConsole.cpp b/src/openrct2/interface/InteractiveConsole.cpp
index 0ef9aedee9..2e07c59e17 100644
--- a/src/openrct2/interface/InteractiveConsole.cpp
+++ b/src/openrct2/interface/InteractiveConsole.cpp
@@ -482,7 +482,7 @@ static int32_t cc_staff(InteractiveConsole& console, const arguments_t& argv)
 
                 if (int_valid[0] && int_valid[1])
                 {
-                    Peep* peep = GetEntity<Peep>(int_val[0]);
+                    Peep* peep = GetEntity<Peep>(EntityId::FromUnderlying(int_val[0]));
                     if (peep != nullptr)
                     {
                         peep->Energy = int_val[1];
@@ -501,7 +501,7 @@ static int32_t cc_staff(InteractiveConsole& console, const arguments_t& argv)
                     console.WriteLineError("Invalid staff ID");
                     return 1;
                 }
-                auto staff = GetEntity<Staff>(int_val[0]);
+                auto staff = GetEntity<Staff>(EntityId::FromUnderlying(int_val[0]));
                 if (staff == nullptr)
                 {
                     console.WriteLineError("Invalid staff ID");
@@ -519,7 +519,7 @@ static int32_t cc_staff(InteractiveConsole& console, const arguments_t& argv)
                 }
 
                 EntertainerCostume costume = static_cast<EntertainerCostume>(int_val[1]);
-                auto staffSetCostumeAction = StaffSetCostumeAction(int_val[0], costume);
+                auto staffSetCostumeAction = StaffSetCostumeAction(EntityId::FromUnderlying(int_val[0]), costume);
                 GameActions::Execute(&staffSetCostumeAction);
             }
         }
diff --git a/src/openrct2/interface/Viewport.cpp b/src/openrct2/interface/Viewport.cpp
index 8e4b31c927..0914fe217b 100644
--- a/src/openrct2/interface/Viewport.cpp
+++ b/src/openrct2/interface/Viewport.cpp
@@ -192,7 +192,7 @@ void viewport_create(rct_window* w, const ScreenCoordsXY& screenCoords, int32_t
         [](auto&& arg) {
             using T = std::decay_t<decltype(arg)>;
             if constexpr (std::is_same_v<T, Focus::CoordinateFocus>)
-                return SPRITE_INDEX_NULL;
+                return EntityId::GetNull();
             else if constexpr (std::is_same_v<T, Focus::EntityFocus>)
                 return arg;
         },
@@ -533,7 +533,7 @@ static void viewport_move(const ScreenCoordsXY& coords, rct_window* w, rct_viewp
 static void viewport_set_underground_flag(int32_t underground, rct_window* window, rct_viewport* viewport)
 {
     if (window->classification != WC_MAIN_WINDOW
-        || (window->classification == WC_MAIN_WINDOW && window->viewport_smart_follow_sprite != SPRITE_INDEX_NULL))
+        || (window->classification == WC_MAIN_WINDOW && !window->viewport_smart_follow_sprite.IsNull()))
     {
         if (!underground)
         {
@@ -565,12 +565,12 @@ void viewport_update_position(rct_window* window)
     if (viewport == nullptr)
         return;
 
-    if (window->viewport_smart_follow_sprite != SPRITE_INDEX_NULL)
+    if (!window->viewport_smart_follow_sprite.IsNull())
     {
         viewport_update_smart_sprite_follow(window);
     }
 
-    if (window->viewport_target_sprite != SPRITE_INDEX_NULL)
+    if (!window->viewport_target_sprite.IsNull())
     {
         viewport_update_sprite_follow(window);
         return;
@@ -660,7 +660,7 @@ void viewport_update_position(rct_window* window)
 
 void viewport_update_sprite_follow(rct_window* window)
 {
-    if (window->viewport_target_sprite != SPRITE_INDEX_NULL && window->viewport != nullptr)
+    if (!window->viewport_target_sprite.IsNull() && window->viewport != nullptr)
     {
         auto* sprite = GetEntity(window->viewport_target_sprite);
         if (sprite == nullptr)
@@ -689,8 +689,8 @@ void viewport_update_smart_sprite_follow(rct_window* window)
     auto entity = TryGetEntity(window->viewport_smart_follow_sprite);
     if (entity == nullptr || entity->Type == EntityType::Null)
     {
-        window->viewport_smart_follow_sprite = SPRITE_INDEX_NULL;
-        window->viewport_target_sprite = SPRITE_INDEX_NULL;
+        window->viewport_smart_follow_sprite = EntityId::GetNull();
+        window->viewport_target_sprite = EntityId::GetNull();
         return;
     }
 
@@ -722,8 +722,8 @@ void viewport_update_smart_guest_follow(rct_window* window, const Guest* peep)
 
     if (peep->State == PeepState::Picked)
     {
-        window->viewport_smart_follow_sprite = SPRITE_INDEX_NULL;
-        window->viewport_target_sprite = SPRITE_INDEX_NULL;
+        window->viewport_smart_follow_sprite = EntityId::GetNull();
+        window->viewport_target_sprite = EntityId::GetNull();
         window->focus = std::nullopt; // No focus
         return;
     }
@@ -760,7 +760,7 @@ void viewport_update_smart_guest_follow(rct_window* window, const Guest* peep)
             coordFocus.y = xy.y;
             coordFocus.z = tile_element_height(xy) + (4 * COORDS_Z_STEP);
             focus = Focus(coordFocus);
-            window->viewport_target_sprite = SPRITE_INDEX_NULL;
+            window->viewport_target_sprite = EntityId::GetNull();
         }
     }
 
@@ -771,8 +771,8 @@ void viewport_update_smart_staff_follow(rct_window* window, const Staff* peep)
 {
     if (peep->State == PeepState::Picked)
     {
-        window->viewport_smart_follow_sprite = SPRITE_INDEX_NULL;
-        window->viewport_target_sprite = SPRITE_INDEX_NULL;
+        window->viewport_smart_follow_sprite = EntityId::GetNull();
+        window->viewport_target_sprite = EntityId::GetNull();
         window->focus = std::nullopt;
         return;
     }
diff --git a/src/openrct2/interface/Window.cpp b/src/openrct2/interface/Window.cpp
index c312f3ffc2..66306ec60c 100644
--- a/src/openrct2/interface/Window.cpp
+++ b/src/openrct2/interface/Window.cpp
@@ -300,6 +300,12 @@ void window_close_by_number(rct_windowclass cls, rct_windownumber number)
     window_close_by_condition([cls, number](rct_window* w) -> bool { return w->classification == cls && w->number == number; });
 }
 
+// TODO: Refactor this to use variant once the new window class is done.
+void window_close_by_number(rct_windowclass cls, EntityId number)
+{
+    window_close_by_number(cls, static_cast<rct_windownumber>(number.ToUnderlying()));
+}
+
 /**
  * Finds the first window with the specified window class.
  *  rct2: 0x006EA8A0
@@ -337,6 +343,12 @@ rct_window* window_find_by_number(rct_windowclass cls, rct_windownumber number)
     return nullptr;
 }
 
+// TODO: Use variant for this once the window framework is done.
+rct_window* window_find_by_number(rct_windowclass cls, EntityId id)
+{
+    return window_find_by_number(cls, static_cast<rct_windownumber>(id.ToUnderlying()));
+}
+
 /**
  * Closes the top-most window
  *
@@ -491,6 +503,12 @@ void window_invalidate_by_number(rct_windowclass cls, rct_windownumber number)
         [cls, number](rct_window* w) -> bool { return w->classification == cls && w->number == number; });
 }
 
+// TODO: Use variant for this once the window framework is done.
+void window_invalidate_by_number(rct_windowclass cls, EntityId id)
+{
+    window_invalidate_by_number(cls, static_cast<rct_windownumber>(id.ToUnderlying()));
+}
+
 /**
  * Invalidates all windows.
  */
@@ -867,7 +885,7 @@ void window_scroll_to_location(rct_window* w, const CoordsXYZ& coords)
             }
         }
         // rct2: 0x006E7C76
-        if (w->viewport_target_sprite == SPRITE_INDEX_NULL)
+        if (w->viewport_target_sprite.IsNull())
         {
             if (!(w->flags & WF_NO_SCROLLING))
             {
@@ -2121,18 +2139,18 @@ void window_init_all()
     window_close_all_except_flags(0);
 }
 
-void window_follow_sprite(rct_window* w, size_t spriteIndex)
+void window_follow_sprite(rct_window* w, EntityId spriteIndex)
 {
-    if (spriteIndex < MAX_ENTITIES || spriteIndex == SPRITE_INDEX_NULL)
+    if (spriteIndex.ToUnderlying() < MAX_ENTITIES || spriteIndex.IsNull())
     {
-        w->viewport_smart_follow_sprite = static_cast<uint16_t>(spriteIndex);
+        w->viewport_smart_follow_sprite = spriteIndex;
     }
 }
 
 void window_unfollow_sprite(rct_window* w)
 {
-    w->viewport_smart_follow_sprite = SPRITE_INDEX_NULL;
-    w->viewport_target_sprite = SPRITE_INDEX_NULL;
+    w->viewport_smart_follow_sprite = EntityId::GetNull();
+    w->viewport_target_sprite = EntityId::GetNull();
 }
 
 rct_viewport* window_get_viewport(rct_window* w)
diff --git a/src/openrct2/interface/Window.h b/src/openrct2/interface/Window.h
index f2ff9c7f0f..404c28f5e0 100644
--- a/src/openrct2/interface/Window.h
+++ b/src/openrct2/interface/Window.h
@@ -9,6 +9,7 @@
 
 #pragma once
 
+#include "../Identifiers.h"
 #include "../common.h"
 #include "../localisation/Formatter.h"
 #include "../ride/RideTypes.h"
@@ -197,7 +198,7 @@ constexpr auto WINDOW_SCROLL_UNDEFINED = std::numeric_limits<uint16_t>::max();
 struct Focus
 {
     using CoordinateFocus = CoordsXYZ;
-    using EntityFocus = uint16_t;
+    using EntityFocus = EntityId;
 
     ZoomLevel zoom{};
     std::variant<CoordinateFocus, EntityFocus> data;
@@ -713,16 +714,19 @@ rct_window* WindowCreateCentred(
 void window_close(rct_window* window);
 void window_close_by_class(rct_windowclass cls);
 void window_close_by_number(rct_windowclass cls, rct_windownumber number);
+void window_close_by_number(rct_windowclass cls, EntityId number);
 void window_close_top();
 void window_close_all();
 void window_close_all_except_class(rct_windowclass cls);
 void window_close_all_except_flags(uint16_t flags);
 rct_window* window_find_by_class(rct_windowclass cls);
 rct_window* window_find_by_number(rct_windowclass cls, rct_windownumber number);
+rct_window* window_find_by_number(rct_windowclass cls, EntityId id);
 rct_window* window_find_from_point(const ScreenCoordsXY& screenCoords);
 rct_widgetindex window_find_widget_from_point(rct_window* w, const ScreenCoordsXY& screenCoords);
 void window_invalidate_by_class(rct_windowclass cls);
 void window_invalidate_by_number(rct_windowclass cls, rct_windownumber number);
+void window_invalidate_by_number(rct_windowclass cls, EntityId id);
 void window_invalidate_all();
 void widget_invalidate(rct_window* w, rct_widgetindex widgetIndex);
 void widget_invalidate_by_class(rct_windowclass cls, rct_widgetindex widgetIndex);
@@ -851,7 +855,7 @@ void window_footpath_keyboard_shortcut_slope_up();
 void window_footpath_keyboard_shortcut_build_current();
 void window_footpath_keyboard_shortcut_demolish_current();
 
-void window_follow_sprite(rct_window* w, size_t spriteIndex);
+void window_follow_sprite(rct_window* w, EntityId spriteIndex);
 void window_unfollow_sprite(rct_window* w);
 
 bool window_ride_construction_update_state(
diff --git a/src/openrct2/interface/Window_internal.h b/src/openrct2/interface/Window_internal.h
index efbab2cccc..36ed878251 100644
--- a/src/openrct2/interface/Window_internal.h
+++ b/src/openrct2/interface/Window_internal.h
@@ -96,12 +96,12 @@ struct rct_window
     };
     int16_t selected_tab{};
     int16_t var_4AE{};
-    uint16_t viewport_target_sprite{};
+    EntityId viewport_target_sprite{ EntityId::GetNull() };
     ScreenCoordsXY savedViewPos{};
     rct_windowclass classification{};
     colour_t colours[6]{};
     VisibilityCache visibility{};
-    uint16_t viewport_smart_follow_sprite = SPRITE_INDEX_NULL; // Handles setting viewport target sprite etc
+    EntityId viewport_smart_follow_sprite{ EntityId::GetNull() }; // Handles setting viewport target sprite etc
 
     void SetLocation(const CoordsXYZ& coords);
     void ScrollToViewport();
diff --git a/src/openrct2/localisation/Formatter.h b/src/openrct2/localisation/Formatter.h
index bc67042eaf..51073d3fd5 100644
--- a/src/openrct2/localisation/Formatter.h
+++ b/src/openrct2/localisation/Formatter.h
@@ -92,6 +92,7 @@ public:
             std::is_same_v<typename std::remove_cv_t<TSpecified>, money32> ||
             std::is_same_v<typename std::remove_cv_t<TSpecified>, money64> ||
             std::is_same_v<typename std::remove_cv_t<TSpecified>, RideId> ||
+            std::is_same_v<typename std::remove_cv_t<TSpecified>, EntityId> ||
             std::is_same_v<typename std::remove_cv_t<TSpecified>, rct_string_id> ||
             std::is_same_v<typename std::remove_cv_t<TSpecified>, uint16_t> ||
             std::is_same_v<typename std::remove_cv_t<TSpecified>, uint32_t> ||
@@ -105,6 +106,10 @@ public:
         {
             convertedValue = static_cast<uint64_t>(value.ToUnderlying());
         }
+        else if constexpr (std::is_same_v<std::remove_cv_t<TDeduced>, EntityId>)
+        {
+            convertedValue = static_cast<uint64_t>(value.ToUnderlying());
+        }
         else if constexpr (std::is_integral_v<TSpecified> || std::is_enum_v<TSpecified>)
         {
             convertedValue = static_cast<uint64_t>(value);
diff --git a/src/openrct2/management/NewsItem.cpp b/src/openrct2/management/NewsItem.cpp
index abc06f42ba..b6f0db5e83 100644
--- a/src/openrct2/management/NewsItem.cpp
+++ b/src/openrct2/management/NewsItem.cpp
@@ -224,7 +224,7 @@ std::optional<CoordsXYZ> News::GetSubjectLocation(News::ItemType type, int32_t s
         }
         case News::ItemType::PeepOnRide:
         {
-            auto peep = TryGetEntity<Peep>(subject);
+            auto peep = TryGetEntity<Peep>(EntityId::FromUnderlying(subject));
             if (peep == nullptr)
                 break;
 
@@ -261,7 +261,7 @@ std::optional<CoordsXYZ> News::GetSubjectLocation(News::ItemType type, int32_t s
         }
         case News::ItemType::Peep:
         {
-            auto peep = TryGetEntity<Peep>(subject);
+            auto peep = TryGetEntity<Peep>(EntityId::FromUnderlying(subject));
             if (peep != nullptr)
             {
                 subjectLoc = peep->GetLocation();
@@ -314,6 +314,12 @@ News::Item* News::AddItemToQueue(News::ItemType type, rct_string_id string_id, u
     return News::AddItemToQueue(type, buffer, assoc);
 }
 
+// TODO: Use variant for assoc, requires strong type for each possible input.
+News::Item* News::AddItemToQueue(ItemType type, rct_string_id string_id, EntityId assoc, const Formatter& formatter)
+{
+    return AddItemToQueue(type, string_id, assoc.ToUnderlying(), formatter);
+}
+
 News::Item* News::AddItemToQueue(News::ItemType type, const utf8* text, uint32_t assoc)
 {
     News::Item* newsItem = gNewsItems.FirstOpenOrNewSlot();
@@ -367,7 +373,7 @@ void News::OpenSubject(News::ItemType type, int32_t subject)
         case News::ItemType::PeepOnRide:
         case News::ItemType::Peep:
         {
-            auto peep = TryGetEntity<Peep>(subject);
+            auto peep = TryGetEntity<Peep>(EntityId::FromUnderlying(subject));
             if (peep != nullptr)
             {
                 auto intent = Intent(WC_PEEP);
diff --git a/src/openrct2/management/NewsItem.h b/src/openrct2/management/NewsItem.h
index 52948bbc60..9ffdb2e131 100644
--- a/src/openrct2/management/NewsItem.h
+++ b/src/openrct2/management/NewsItem.h
@@ -9,6 +9,7 @@
 
 #pragma once
 
+#include "../Identifiers.h"
 #include "../common.h"
 #include "../core/String.hpp"
 
@@ -292,6 +293,7 @@ namespace News
     std::optional<CoordsXYZ> GetSubjectLocation(News::ItemType type, int32_t subject);
 
     News::Item* AddItemToQueue(News::ItemType type, rct_string_id string_id, uint32_t assoc, const Formatter& formatter);
+    News::Item* AddItemToQueue(News::ItemType type, rct_string_id string_id, EntityId assoc, const Formatter& formatter);
     News::Item* AddItemToQueue(News::ItemType type, const utf8* text, uint32_t assoc);
 
     bool CheckIfItemRequiresAssoc(News::ItemType type);
diff --git a/src/openrct2/paint/tile_element/Paint.Path.cpp b/src/openrct2/paint/tile_element/Paint.Path.cpp
index 38ff6bb0e2..2d109c921c 100644
--- a/src/openrct2/paint/tile_element/Paint.Path.cpp
+++ b/src/openrct2/paint/tile_element/Paint.Path.cpp
@@ -900,14 +900,16 @@ static void PaintPatrolAreas(paint_session& session, const PathElement& pathEl)
 {
     if (gStaffDrawPatrolAreas != 0xFFFF)
     {
+        // TODO: Split this into two.
         auto staffIndex = gStaffDrawPatrolAreas;
         auto staffType = static_cast<StaffType>(staffIndex & 0x7FFF);
         auto is_staff_list = staffIndex & 0x8000;
+
         auto patrolColour = COLOUR_LIGHT_BLUE;
 
         if (!is_staff_list)
         {
-            Staff* staff = GetEntity<Staff>(staffIndex);
+            Staff* staff = GetEntity<Staff>(EntityId::FromUnderlying(staffIndex));
             if (staff == nullptr)
             {
                 log_error("Invalid staff index for draw patrol areas!");
diff --git a/src/openrct2/paint/tile_element/Paint.Surface.cpp b/src/openrct2/paint/tile_element/Paint.Surface.cpp
index 92c83d4911..7f23d95bcb 100644
--- a/src/openrct2/paint/tile_element/Paint.Surface.cpp
+++ b/src/openrct2/paint/tile_element/Paint.Surface.cpp
@@ -1105,6 +1105,7 @@ void PaintSurface(paint_session& session, uint8_t direction, uint16_t height, co
     // loc_660D02
     if (gStaffDrawPatrolAreas != SPRITE_INDEX_NULL)
     {
+        // TODO: Split is_staff_list into a new variable.
         const int32_t staffIndex = gStaffDrawPatrolAreas;
         const bool is_staff_list = staffIndex & 0x8000;
         const int16_t x = session.MapPosition.x, y = session.MapPosition.y;
@@ -1115,7 +1116,7 @@ void PaintSurface(paint_session& session, uint8_t direction, uint16_t height, co
 
         if (!is_staff_list)
         {
-            Staff* staff = GetEntity<Staff>(staffIndex);
+            Staff* staff = GetEntity<Staff>(EntityId::FromUnderlying(staffIndex));
             if (staff == nullptr)
             {
                 log_error("Invalid staff index for draw patrol areas!");
diff --git a/src/openrct2/park/ParkFile.cpp b/src/openrct2/park/ParkFile.cpp
index b3a86cf73c..8cd03c1dc6 100644
--- a/src/openrct2/park/ParkFile.cpp
+++ b/src/openrct2/park/ParkFile.cpp
@@ -1160,7 +1160,7 @@ namespace OpenRCT2
 
                     cs.ReadWrite(ride.min_waiting_time);
                     cs.ReadWrite(ride.max_waiting_time);
-                    cs.ReadWriteArray(ride.vehicles, [&cs](uint16_t& v) {
+                    cs.ReadWriteArray(ride.vehicles, [&cs](EntityId& v) {
                         cs.ReadWrite(v);
                         return true;
                     });
@@ -2168,7 +2168,7 @@ namespace OpenRCT2
         {
             T placeholder{};
 
-            auto index = cs.Read<uint16_t>();
+            auto index = cs.Read<EntityId>();
             auto* ent = CreateEntityAt<T>(index);
             if (ent == nullptr)
             {
diff --git a/src/openrct2/peep/RideUseSystem.h b/src/openrct2/peep/RideUseSystem.h
index 822f2d136c..4074ba2e26 100644
--- a/src/openrct2/peep/RideUseSystem.h
+++ b/src/openrct2/peep/RideUseSystem.h
@@ -13,8 +13,8 @@
 
 namespace OpenRCT2::RideUse
 {
-    using RideHistory = GroupVector<uint16_t, RideId>;
-    using RideTypeHistory = GroupVector<uint16_t, uint16_t>;
+    using RideHistory = GroupVector<EntityId, RideId>;
+    using RideTypeHistory = GroupVector<EntityId, uint16_t>;
 
     RideHistory& GetHistory();
     RideTypeHistory& GetTypeHistory();
diff --git a/src/openrct2/rct1/S4Importer.cpp b/src/openrct2/rct1/S4Importer.cpp
index da129197a7..f255e107bb 100644
--- a/src/openrct2/rct1/S4Importer.cpp
+++ b/src/openrct2/rct1/S4Importer.cpp
@@ -872,7 +872,7 @@ namespace RCT1
                     ride_set_exit_location(dst, i, { src->exit[i].x, src->exit[i].y, src->station_height[i] / 2, 0 });
 
                 dst->stations[i].QueueTime = src->queue_time[i];
-                dst->stations[i].LastPeepInQueue = src->last_peep_in_queue[i];
+                dst->stations[i].LastPeepInQueue = EntityId::FromUnderlying(src->last_peep_in_queue[i]);
                 dst->stations[i].QueueLength = src->num_peeps_in_queue[i];
 
                 dst->stations[i].SegmentTime = src->time[i];
@@ -885,7 +885,7 @@ namespace RCT1
                 dst->stations[i].TrainAtStation = RideStation::NO_TRAIN;
                 ride_clear_entrance_location(dst, i);
                 ride_clear_exit_location(dst, i);
-                dst->stations[i].LastPeepInQueue = SPRITE_INDEX_NULL;
+                dst->stations[i].LastPeepInQueue = EntityId::GetNull();
             }
 
             dst->num_stations = src->num_stations;
@@ -893,11 +893,11 @@ namespace RCT1
             // Vehicle links (indexes converted later)
             for (int32_t i = 0; i < Limits::MaxTrainsPerRide; i++)
             {
-                dst->vehicles[i] = src->vehicles[i];
+                dst->vehicles[i] = EntityId::FromUnderlying(src->vehicles[i]);
             }
             for (int32_t i = Limits::MaxTrainsPerRide; i <= OpenRCT2::Limits::MaxTrainsPerRide; i++)
             {
-                dst->vehicles[i] = SPRITE_INDEX_NULL;
+                dst->vehicles[i] = EntityId::GetNull();
             }
 
             dst->num_vehicles = src->num_trains;
@@ -971,7 +971,7 @@ namespace RCT1
             dst->downtime = src->downtime;
             dst->breakdown_reason = src->breakdown_reason;
             dst->mechanic_status = src->mechanic_status;
-            dst->mechanic = src->mechanic;
+            dst->mechanic = EntityId::FromUnderlying(src->mechanic);
             dst->breakdown_reason_pending = src->breakdown_reason_pending;
             dst->inspection_station = src->inspection_station;
             dst->broken_car = src->broken_car;
@@ -2702,7 +2702,7 @@ namespace RCT1
 
     template<> void S4Importer::ImportEntity<::Vehicle>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<::Vehicle>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<::Vehicle>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT1::Vehicle*>(&srcBase);
         const auto* ride = get_ride(RideId::FromUnderlying(src->ride));
         if (ride == nullptr)
@@ -2759,16 +2759,16 @@ namespace RCT1
         dst->seat_rotation = DEFAULT_SEAT_ROTATION;
 
         // Vehicle links (indexes converted later)
-        dst->prev_vehicle_on_ride = src->prev_vehicle_on_ride;
-        dst->next_vehicle_on_ride = src->next_vehicle_on_ride;
-        dst->next_vehicle_on_train = src->next_vehicle_on_train;
+        dst->prev_vehicle_on_ride = EntityId::FromUnderlying(src->prev_vehicle_on_ride);
+        dst->next_vehicle_on_ride = EntityId::FromUnderlying(src->next_vehicle_on_ride);
+        dst->next_vehicle_on_train = EntityId::FromUnderlying(src->next_vehicle_on_train);
 
         // Guests (indexes converted later)
         for (int i = 0; i < 32; i++)
         {
-            uint16_t spriteIndex = src->peep[i];
+            const auto spriteIndex = EntityId::FromUnderlying(src->peep[i]);
             dst->peep[i] = spriteIndex;
-            if (spriteIndex != SPRITE_INDEX_NULL)
+            if (spriteIndex.IsNull())
             {
                 dst->peep_tshirt_colours[i] = RCT1::GetColour(src->peep_tshirt_colours[i]);
             }
@@ -2814,7 +2814,7 @@ namespace RCT1
 
     template<> void S4Importer::ImportEntity<Guest>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<Guest>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<Guest>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT1::Peep*>(&srcBase);
         ImportPeep(dst, src);
 
@@ -2886,7 +2886,7 @@ namespace RCT1
         dst->PreviousRideTimeOut = src->previous_ride_time_out;
         dst->GuestHeadingToRideId = RCT12RideIdToOpenRCT2RideId(src->guest_heading_to_ride_id);
         dst->GuestIsLostCountdown = src->peep_is_lost_countdown;
-        dst->GuestNextInQueue = src->next_in_queue;
+        dst->GuestNextInQueue = EntityId::FromUnderlying(src->next_in_queue);
         // Guests' favourite ride was only saved in LL.
         // Set it to N/A if the save comes from the original or AA.
         if (_gameVersion == FILE_VERSION_RCT1_LL)
@@ -2914,7 +2914,7 @@ namespace RCT1
 
     template<> void S4Importer::ImportEntity<Staff>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<Staff>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<Staff>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT1::Peep*>(&srcBase);
         ImportPeep(dst, src);
         dst->AssignedStaffType = StaffType(src->staff_type);
@@ -2932,7 +2932,7 @@ namespace RCT1
 
     template<> void S4Importer::ImportEntity<Litter>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<Litter>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<Litter>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT12SpriteLitter*>(&srcBase);
         ImportEntityCommonProperties(dst, src);
 
@@ -2941,7 +2941,7 @@ namespace RCT1
 
     template<> void S4Importer::ImportEntity<SteamParticle>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<SteamParticle>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<SteamParticle>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT12SpriteSteamParticle*>(&srcBase);
 
         ImportEntityCommonProperties(dst, src);
@@ -2950,7 +2950,7 @@ namespace RCT1
 
     template<> void S4Importer::ImportEntity<MoneyEffect>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<MoneyEffect>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<MoneyEffect>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT12SpriteMoneyEffect*>(&srcBase);
 
         ImportEntityCommonProperties(dst, src);
@@ -2963,35 +2963,35 @@ namespace RCT1
 
     template<> void S4Importer::ImportEntity<VehicleCrashParticle>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<VehicleCrashParticle>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<VehicleCrashParticle>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT12SpriteCrashedVehicleParticle*>(&srcBase);
         ImportEntityCommonProperties(dst, src);
     }
 
     template<> void S4Importer::ImportEntity<ExplosionCloud>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<ExplosionCloud>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<ExplosionCloud>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT12SpriteParticle*>(&srcBase);
         ImportEntityCommonProperties(dst, src);
     }
 
     template<> void S4Importer::ImportEntity<ExplosionFlare>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<ExplosionFlare>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<ExplosionFlare>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT12SpriteParticle*>(&srcBase);
         ImportEntityCommonProperties(dst, src);
     }
 
     template<> void S4Importer::ImportEntity<CrashSplashParticle>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<CrashSplashParticle>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<CrashSplashParticle>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT12SpriteParticle*>(&srcBase);
         ImportEntityCommonProperties(dst, src);
     }
 
     template<> void S4Importer::ImportEntity<JumpingFountain>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<JumpingFountain>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<JumpingFountain>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT12SpriteJumpingFountain*>(&srcBase);
 
         ImportEntityCommonProperties(dst, src);
@@ -3004,7 +3004,7 @@ namespace RCT1
 
     template<> void S4Importer::ImportEntity<Balloon>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<Balloon>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<Balloon>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT12SpriteBalloon*>(&srcBase);
 
         ImportEntityCommonProperties(dst, src);
@@ -3021,7 +3021,7 @@ namespace RCT1
 
     template<> void S4Importer::ImportEntity<Duck>(const RCT12SpriteBase& srcBase)
     {
-        auto* dst = CreateEntityAt<Duck>(srcBase.sprite_index);
+        auto* dst = CreateEntityAt<Duck>(EntityId::FromUnderlying(srcBase.sprite_index));
         auto* src = static_cast<const RCT12SpriteDuck*>(&srcBase);
 
         ImportEntityCommonProperties(dst, src);
diff --git a/src/openrct2/rct2/S6Importer.cpp b/src/openrct2/rct2/S6Importer.cpp
index 011f51ade0..18707d1c6d 100644
--- a/src/openrct2/rct2/S6Importer.cpp
+++ b/src/openrct2/rct2/S6Importer.cpp
@@ -705,7 +705,7 @@ namespace RCT2
                 else
                     ride_set_exit_location(dst, i, { src->exits[i].x, src->exits[i].y, src->station_heights[i], 0 });
 
-                dst->stations[i].LastPeepInQueue = src->last_peep_in_queue[i];
+                dst->stations[i].LastPeepInQueue = EntityId::FromUnderlying(src->last_peep_in_queue[i]);
 
                 dst->stations[i].SegmentLength = src->length[i];
                 dst->stations[i].SegmentTime = src->time[i];
@@ -721,16 +721,16 @@ namespace RCT2
                 dst->stations[i].TrainAtStation = RideStation::NO_TRAIN;
                 ride_clear_entrance_location(dst, i);
                 ride_clear_exit_location(dst, i);
-                dst->stations[i].LastPeepInQueue = SPRITE_INDEX_NULL;
+                dst->stations[i].LastPeepInQueue = EntityId::GetNull();
             }
 
             for (int32_t i = 0; i < Limits::MaxTrainsPerRide; i++)
             {
-                dst->vehicles[i] = src->vehicles[i];
+                dst->vehicles[i] = EntityId::FromUnderlying(src->vehicles[i]);
             }
             for (int32_t i = Limits::MaxTrainsPerRide - 1; i <= OpenRCT2::Limits::MaxTrainsPerRide; i++)
             {
-                dst->vehicles[i] = SPRITE_INDEX_NULL;
+                dst->vehicles[i] = EntityId::GetNull();
             }
 
             dst->depart_flags = src->depart_flags;
@@ -833,7 +833,7 @@ namespace RCT2
             dst->music_tune_id = src->music_tune_id;
             dst->slide_in_use = src->slide_in_use;
             // Includes maze_tiles
-            dst->slide_peep = src->slide_peep;
+            dst->slide_peep = EntityId::FromUnderlying(src->slide_peep);
             // pad_160[0xE];
             dst->slide_peep_t_shirt_colour = src->slide_peep_t_shirt_colour;
             // pad_16F[0x7];
@@ -841,13 +841,13 @@ namespace RCT2
             // pad_177[0x9];
             dst->build_date = static_cast<int32_t>(src->build_date);
             dst->upkeep_cost = src->upkeep_cost;
-            dst->race_winner = src->race_winner;
+            dst->race_winner = EntityId::FromUnderlying(src->race_winner);
             // pad_186[0x02];
             dst->music_position = src->music_position;
 
             dst->breakdown_reason_pending = src->breakdown_reason_pending;
             dst->mechanic_status = src->mechanic_status;
-            dst->mechanic = src->mechanic;
+            dst->mechanic = EntityId::FromUnderlying(src->mechanic);
             dst->inspection_station = src->inspection_station;
             dst->broken_vehicle = src->broken_vehicle;
             dst->broken_car = src->broken_car;
@@ -924,7 +924,7 @@ namespace RCT2
             dst->num_circuits = src->num_circuits;
             dst->CableLiftLoc = { src->cable_lift_x, src->cable_lift_y, src->cable_lift_z * COORDS_Z_STEP };
             // pad_1FD;
-            dst->cable_lift = src->cable_lift;
+            dst->cable_lift = EntityId::FromUnderlying(src->cable_lift);
 
             // pad_208[0x58];
         }
@@ -1660,7 +1660,7 @@ namespace RCT2
         {
             dst->Type = GetEntityTypeFromRCT2Sprite(src);
             dst->sprite_height_negative = src->sprite_height_negative;
-            dst->sprite_index = src->sprite_index;
+            dst->sprite_index = EntityId::FromUnderlying(src->sprite_index);
             dst->x = src->x;
             dst->y = src->y;
             dst->z = src->z;
@@ -1784,7 +1784,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::Vehicle>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::Vehicle>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::Vehicle>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const RCT2::Vehicle*>(&baseSrc);
         const auto& ride = _s6.rides[src->ride];
 
@@ -1832,9 +1832,9 @@ namespace RCT2
             dst->SetTrackType(0);
         }
 
-        dst->next_vehicle_on_train = src->next_vehicle_on_train;
-        dst->prev_vehicle_on_ride = src->prev_vehicle_on_ride;
-        dst->next_vehicle_on_ride = src->next_vehicle_on_ride;
+        dst->next_vehicle_on_train = EntityId::FromUnderlying(src->next_vehicle_on_train);
+        dst->prev_vehicle_on_ride = EntityId::FromUnderlying(src->prev_vehicle_on_ride);
+        dst->next_vehicle_on_ride = EntityId::FromUnderlying(src->next_vehicle_on_ride);
         dst->var_44 = src->var_44;
         dst->mass = src->mass;
         dst->update_flags = src->update_flags;
@@ -1853,7 +1853,7 @@ namespace RCT2
         dst->sub_state = src->sub_state;
         for (size_t i = 0; i < std::size(src->peep); i++)
         {
-            dst->peep[i] = src->peep[i];
+            dst->peep[i] = EntityId::FromUnderlying(src->peep[i]);
             dst->peep_tshirt_colours[i] = src->peep_tshirt_colours[i];
         }
         dst->num_seats = src->num_seats;
@@ -1901,7 +1901,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::Guest>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::Guest>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::Guest>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const Peep*>(&baseSrc);
         ImportEntityPeep(dst, src);
 
@@ -1927,7 +1927,7 @@ namespace RCT2
         dst->Photo2RideRef = RCT12RideIdToOpenRCT2RideId(src->photo2_ride_ref);
         dst->Photo3RideRef = RCT12RideIdToOpenRCT2RideId(src->photo3_ride_ref);
         dst->Photo4RideRef = RCT12RideIdToOpenRCT2RideId(src->photo4_ride_ref);
-        dst->GuestNextInQueue = src->next_in_queue;
+        dst->GuestNextInQueue = EntityId::FromUnderlying(src->next_in_queue);
         dst->TimeInQueue = src->time_in_queue;
         dst->CashInPocket = src->cash_in_pocket;
         dst->CashSpent = src->cash_spent;
@@ -1975,7 +1975,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::Staff>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::Staff>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::Staff>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const Peep*>(&baseSrc);
         ImportEntityPeep(dst, src);
 
@@ -1995,7 +1995,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::SteamParticle>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::SteamParticle>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::SteamParticle>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const RCT12SpriteSteamParticle*>(&baseSrc);
         ImportEntityCommonProperties(dst, src);
         dst->time_to_move = src->time_to_move;
@@ -2004,7 +2004,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::MoneyEffect>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::MoneyEffect>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::MoneyEffect>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const RCT12SpriteMoneyEffect*>(&baseSrc);
         ImportEntityCommonProperties(dst, src);
         dst->MoveDelay = src->move_delay;
@@ -2017,7 +2017,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::VehicleCrashParticle>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::VehicleCrashParticle>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::VehicleCrashParticle>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const RCT12SpriteCrashedVehicleParticle*>(&baseSrc);
         ImportEntityCommonProperties(dst, src);
         dst->frame = src->frame;
@@ -2036,7 +2036,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::ExplosionCloud>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::ExplosionCloud>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::ExplosionCloud>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const RCT12SpriteParticle*>(&baseSrc);
         ImportEntityCommonProperties(dst, src);
         dst->frame = src->frame;
@@ -2044,7 +2044,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::ExplosionFlare>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::ExplosionFlare>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::ExplosionFlare>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const RCT12SpriteParticle*>(&baseSrc);
         ImportEntityCommonProperties(dst, src);
         dst->frame = src->frame;
@@ -2052,7 +2052,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::CrashSplashParticle>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::CrashSplashParticle>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::CrashSplashParticle>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const RCT12SpriteParticle*>(&baseSrc);
         ImportEntityCommonProperties(dst, src);
         dst->frame = src->frame;
@@ -2060,7 +2060,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::JumpingFountain>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::JumpingFountain>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::JumpingFountain>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const RCT12SpriteJumpingFountain*>(&baseSrc);
         ImportEntityCommonProperties(dst, src);
         dst->NumTicksAlive = src->num_ticks_alive;
@@ -2076,7 +2076,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::Balloon>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::Balloon>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::Balloon>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const RCT12SpriteBalloon*>(&baseSrc);
         ImportEntityCommonProperties(dst, src);
         dst->popped = src->popped;
@@ -2087,7 +2087,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::Duck>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::Duck>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::Duck>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const RCT12SpriteDuck*>(&baseSrc);
         ImportEntityCommonProperties(dst, src);
         dst->frame = src->frame;
@@ -2098,7 +2098,7 @@ namespace RCT2
 
     template<> void S6Importer::ImportEntity<::Litter>(const RCT12SpriteBase& baseSrc)
     {
-        auto dst = CreateEntityAt<::Litter>(baseSrc.sprite_index);
+        auto dst = CreateEntityAt<::Litter>(EntityId::FromUnderlying(baseSrc.sprite_index));
         auto src = static_cast<const RCT12SpriteLitter*>(&baseSrc);
         ImportEntityCommonProperties(dst, src);
         dst->SubType = ::Litter::Type(src->type);
diff --git a/src/openrct2/ride/CableLift.cpp b/src/openrct2/ride/CableLift.cpp
index 70cdbfebbe..ca49619f3d 100644
--- a/src/openrct2/ride/CableLift.cpp
+++ b/src/openrct2/ride/CableLift.cpp
@@ -60,7 +60,7 @@ Vehicle* cable_lift_segment_create(
     current->bank_rotation = 0;
     for (auto& peep : current->peep)
     {
-        peep = SPRITE_INDEX_NULL;
+        peep = EntityId::GetNull();
     }
     current->TrackSubposition = VehicleTrackSubposition::Default;
     current->sprite_direction = direction << 3;
diff --git a/src/openrct2/ride/Ride.cpp b/src/openrct2/ride/Ride.cpp
index 954b436506..acf89f7218 100644
--- a/src/openrct2/ride/Ride.cpp
+++ b/src/openrct2/ride/Ride.cpp
@@ -281,7 +281,7 @@ Guest* Ride::GetQueueHeadGuest(StationIndex stationIndex) const
 {
     Guest* peep;
     Guest* result = nullptr;
-    uint16_t spriteIndex = stations[stationIndex].LastPeepInQueue;
+    auto spriteIndex = stations[stationIndex].LastPeepInQueue;
     while ((peep = TryGetEntity<Guest>(spriteIndex)) != nullptr)
     {
         spriteIndex = peep->GuestNextInQueue;
@@ -294,7 +294,7 @@ void Ride::UpdateQueueLength(StationIndex stationIndex)
 {
     uint16_t count = 0;
     Guest* peep;
-    uint16_t spriteIndex = stations[stationIndex].LastPeepInQueue;
+    auto spriteIndex = stations[stationIndex].LastPeepInQueue;
     while ((peep = TryGetEntity<Guest>(spriteIndex)) != nullptr)
     {
         spriteIndex = peep->GuestNextInQueue;
@@ -308,7 +308,7 @@ void Ride::QueueInsertGuestAtFront(StationIndex stationIndex, Guest* peep)
     assert(stationIndex < OpenRCT2::Limits::MaxStationsPerRide);
     assert(peep != nullptr);
 
-    peep->GuestNextInQueue = SPRITE_INDEX_NULL;
+    peep->GuestNextInQueue = EntityId::GetNull();
     auto* queueHeadGuest = GetQueueHeadGuest(peep->CurrentRideStation);
     if (queueHeadGuest == nullptr)
     {
@@ -809,7 +809,7 @@ void Ride::FormatStatusTo(Formatter& ft) const
     }
     else if (
         mode == RideMode::Race && !(lifecycle_flags & RIDE_LIFECYCLE_PASS_STATION_NO_STOPPING)
-        && race_winner != SPRITE_INDEX_NULL)
+        && !race_winner.IsNull())
     {
         auto peep = GetEntity<Guest>(race_winner);
         if (peep != nullptr)
@@ -1431,7 +1431,7 @@ static void choose_random_train_to_breakdown_safe(Ride* ride)
 
     // Prevent crash caused by accessing SPRITE_INDEX_NULL on hacked rides.
     // This should probably be cleaned up on import instead.
-    while (ride->vehicles[ride->broken_vehicle] == SPRITE_INDEX_NULL && ride->broken_vehicle != 0)
+    while (ride->vehicles[ride->broken_vehicle].IsNull() && ride->broken_vehicle != 0)
     {
         --ride->broken_vehicle;
     }
@@ -2004,7 +2004,7 @@ void ride_measurements_update()
                 // For each vehicle
                 for (int32_t j = 0; j < ride.num_vehicles; j++)
                 {
-                    uint16_t vehicleSpriteIdx = ride.vehicles[j];
+                    auto vehicleSpriteIdx = ride.vehicles[j];
                     auto vehicle = GetEntity<Vehicle>(vehicleSpriteIdx);
                     if (vehicle != nullptr)
                     {
@@ -3127,7 +3127,7 @@ static Vehicle* vehicle_create_car(
     vehicle->sound2_flags = 0;
     vehicle->sound1_id = OpenRCT2::Audio::SoundId::Null;
     vehicle->sound2_id = OpenRCT2::Audio::SoundId::Null;
-    vehicle->next_vehicle_on_train = SPRITE_INDEX_NULL;
+    vehicle->next_vehicle_on_train = EntityId::GetNull();
     vehicle->var_C4 = 0;
     vehicle->animation_frame = 0;
     vehicle->animationState = 0;
@@ -3138,7 +3138,7 @@ static Vehicle* vehicle_create_car(
     vehicle->seat_rotation = 4;
     for (size_t i = 0; i < std::size(vehicle->peep); i++)
     {
-        vehicle->peep[i] = SPRITE_INDEX_NULL;
+        vehicle->peep[i] = EntityId::GetNull();
     }
 
     if (vehicleEntry->flags & VEHICLE_ENTRY_FLAG_DODGEM_CAR_PLACEMENT)
@@ -3348,7 +3348,7 @@ static bool vehicle_create_trains(RideId rideIndex, const CoordsXYZ& trainsPos,
 
         for (int32_t i = 0; i <= OpenRCT2::Limits::MaxTrainsPerRide; i++)
         {
-            if (ride->vehicles[i] == SPRITE_INDEX_NULL)
+            if (ride->vehicles[i].IsNull())
             {
                 ride->vehicles[i] = train.head->sprite_index;
                 break;
@@ -3737,7 +3737,7 @@ static bool ride_create_cable_lift(RideId rideIndex, bool isApplying)
 
         Vehicle* current = cable_lift_segment_create(
             *ride, cableLiftLoc.x, cableLiftLoc.y, cableLiftLoc.z / 8, direction, var_44, remaining_distance, i == 0);
-        current->next_vehicle_on_train = SPRITE_INDEX_NULL;
+        current->next_vehicle_on_train = EntityId::GetNull();
         if (i == 0)
         {
             head = current;
@@ -5236,7 +5236,7 @@ uint32_t ride_customers_in_last_5_minutes(const Ride* ride)
 
 Vehicle* ride_get_broken_vehicle(const Ride* ride)
 {
-    uint16_t vehicleIndex = ride->vehicles[ride->broken_vehicle];
+    auto vehicleIndex = ride->vehicles[ride->broken_vehicle];
     Vehicle* vehicle = GetEntity<Vehicle>(vehicleIndex);
     if (vehicle != nullptr)
     {
diff --git a/src/openrct2/ride/Ride.h b/src/openrct2/ride/Ride.h
index 2159dfbdfe..512cef2cc9 100644
--- a/src/openrct2/ride/Ride.h
+++ b/src/openrct2/ride/Ride.h
@@ -53,7 +53,7 @@ struct RideStation
     uint16_t SegmentTime;  // Time for train to reach the next station from this station.
     uint8_t QueueTime;
     uint16_t QueueLength;
-    uint16_t LastPeepInQueue;
+    EntityId LastPeepInQueue;
 
     static constexpr uint8_t NO_TRAIN = std::numeric_limits<uint8_t>::max();
 
@@ -118,7 +118,7 @@ struct Ride
     std::string custom_name;
     uint16_t default_name_number;
     CoordsXY overall_view;
-    uint16_t vehicles[OpenRCT2::Limits::MaxTrainsPerRide + 1]; // Points to the first car in the train
+    EntityId vehicles[OpenRCT2::Limits::MaxTrainsPerRide + 1]; // Points to the first car in the train
     uint8_t depart_flags;
     uint8_t num_stations;
     uint8_t num_vehicles;
@@ -209,18 +209,18 @@ struct Ride
     uint8_t slide_in_use;
     union
     {
-        uint16_t slide_peep;
+        EntityId slide_peep;
         uint16_t maze_tiles;
     };
     uint8_t slide_peep_t_shirt_colour;
     uint8_t spiral_slide_progress;
     int32_t build_date;
     money16 upkeep_cost;
-    uint16_t race_winner;
+    EntityId race_winner;
     uint32_t music_position;
     uint8_t breakdown_reason_pending;
     uint8_t mechanic_status;
-    uint16_t mechanic;
+    EntityId mechanic;
     StationIndex inspection_station;
     uint8_t broken_vehicle;
     uint8_t broken_car;
@@ -264,7 +264,7 @@ struct Ride
     StationIndex current_test_station;
     uint8_t num_circuits;
     CoordsXYZ CableLiftLoc;
-    uint16_t cable_lift;
+    EntityId cable_lift;
 
     // These two fields are used to warn users about issues.
     // Such issue can be hacked rides with incompatible options set.
diff --git a/src/openrct2/ride/RideConstruction.cpp b/src/openrct2/ride/RideConstruction.cpp
index 8a18168a0d..4401a728d4 100644
--- a/src/openrct2/ride/RideConstruction.cpp
+++ b/src/openrct2/ride/RideConstruction.cpp
@@ -161,7 +161,7 @@ static void ride_remove_cable_lift(Ride* ride)
     if (ride->lifecycle_flags & RIDE_LIFECYCLE_CABLE_LIFT)
     {
         ride->lifecycle_flags &= ~RIDE_LIFECYCLE_CABLE_LIFT;
-        uint16_t spriteIndex = ride->cable_lift;
+        auto spriteIndex = ride->cable_lift;
         do
         {
             Vehicle* vehicle = GetEntity<Vehicle>(spriteIndex);
@@ -172,7 +172,7 @@ static void ride_remove_cable_lift(Ride* ride)
             vehicle->Invalidate();
             spriteIndex = vehicle->next_vehicle_on_train;
             EntityRemove(vehicle);
-        } while (spriteIndex != SPRITE_INDEX_NULL);
+        } while (!spriteIndex.IsNull());
     }
 }
 
@@ -189,8 +189,8 @@ void Ride::RemoveVehicles()
 
         for (size_t i = 0; i <= OpenRCT2::Limits::MaxTrainsPerRide; i++)
         {
-            uint16_t spriteIndex = vehicles[i];
-            while (spriteIndex != SPRITE_INDEX_NULL)
+            auto spriteIndex = vehicles[i];
+            while (!spriteIndex.IsNull())
             {
                 Vehicle* vehicle = GetEntity<Vehicle>(spriteIndex);
                 if (vehicle == nullptr)
@@ -202,7 +202,7 @@ void Ride::RemoveVehicles()
                 EntityRemove(vehicle);
             }
 
-            vehicles[i] = SPRITE_INDEX_NULL;
+            vehicles[i] = EntityId::GetNull();
         }
 
         for (size_t i = 0; i < OpenRCT2::Limits::MaxStationsPerRide; i++)
diff --git a/src/openrct2/ride/TrainManager.h b/src/openrct2/ride/TrainManager.h
index 301780c37c..e7e25f4697 100644
--- a/src/openrct2/ride/TrainManager.h
+++ b/src/openrct2/ride/TrainManager.h
@@ -7,6 +7,9 @@
  * OpenRCT2 is licensed under the GNU General Public License version 3.
  *****************************************************************************/
 #pragma once
+
+#include "../Identifiers.h"
+
 #include <cstdint>
 #include <list>
 
@@ -18,17 +21,17 @@ namespace TrainManager
     class View
     {
     private:
-        const std::list<uint16_t>* vec;
+        const std::list<EntityId>* vec;
 
         class Iterator
         {
         private:
-            std::list<uint16_t>::const_iterator iter;
-            std::list<uint16_t>::const_iterator end;
+            std::list<EntityId>::const_iterator iter;
+            std::list<EntityId>::const_iterator end;
             Vehicle* Entity = nullptr;
 
         public:
-            Iterator(std::list<uint16_t>::const_iterator _iter, std::list<uint16_t>::const_iterator _end)
+            Iterator(std::list<EntityId>::const_iterator _iter, std::list<EntityId>::const_iterator _end)
                 : iter(_iter)
                 , end(_end)
             {
diff --git a/src/openrct2/ride/Vehicle.cpp b/src/openrct2/ride/Vehicle.cpp
index c719c4801b..cac50f6ec9 100644
--- a/src/openrct2/ride/Vehicle.cpp
+++ b/src/openrct2/ride/Vehicle.cpp
@@ -569,7 +569,7 @@ template<> bool EntityBase::Is<Vehicle>() const
  * @param vehicleId Entity id of the vehicle that just crashed
  * @param crashId What the vehicle crashed into. Should be either "another_vehicle", "land", or "water"
  */
-static void InvokeVehicleCrashHook(const uint16_t vehicleId, const std::string_view crashId)
+static void InvokeVehicleCrashHook(const EntityId vehicleId, const std::string_view crashId)
 {
     auto& hookEngine = OpenRCT2::GetContext()->GetScriptEngine().GetHookEngine();
     if (hookEngine.HasSubscriptions(OpenRCT2::Scripting::HOOK_TYPE::VEHICLE_CRASH))
@@ -578,7 +578,7 @@ static void InvokeVehicleCrashHook(const uint16_t vehicleId, const std::string_v
 
         // Create event args object
         auto obj = OpenRCT2::Scripting::DukObject(ctx);
-        obj.Set("id", vehicleId);
+        obj.Set("id", vehicleId.ToUnderlying());
         obj.Set("crashIntoType", crashId);
 
         // Call the subscriptions
@@ -691,7 +691,7 @@ void Vehicle::MoveRelativeDistance(int32_t distance)
     ClearUpdateFlag(VEHICLE_UPDATE_FLAG_SINGLE_CAR_POSITION | VEHICLE_UPDATE_FLAG_COLLISION_DISABLED);
 }
 
-Vehicle* try_get_vehicle(uint16_t spriteIndex)
+Vehicle* try_get_vehicle(EntityId spriteIndex)
 {
     return TryGetEntity<Vehicle>(spriteIndex);
 }
@@ -763,7 +763,7 @@ namespace
 
     private:
         T* Current = nullptr;
-        uint16_t NextVehicleId = SPRITE_INDEX_NULL;
+        EntityId NextVehicleId = EntityId::GetNull();
     };
 } // namespace
 
@@ -835,7 +835,7 @@ uint16_t Vehicle::GetSoundPriority() const
 
     for (const auto& vehicleSound : OpenRCT2::Audio::gVehicleSoundList)
     {
-        if (vehicleSound.id == sprite_index)
+        if (vehicleSound.id == sprite_index.ToUnderlying())
         {
             // Vehicle sounds will get higher priority if they are already playing
             return result + 300;
@@ -890,7 +890,7 @@ OpenRCT2::Audio::VehicleSoundParams Vehicle::CreateSoundParam(uint16_t priority)
     frequency += 11025;
     frequency += 16 * sound_vector_factor;
     param.frequency = static_cast<uint16_t>(frequency);
-    param.id = sprite_index;
+    param.id = sprite_index.ToUnderlying();
     param.volume = 0;
 
     if (x != LOCATION_NULL)
@@ -1210,7 +1210,7 @@ void vehicle_sounds_update()
         vehicleSound->volume = tempvolume;
         panVol = std::max(0, panVol - tempvolume);
 
-        Vehicle* vehicle = GetEntity<Vehicle>(vehicleSoundParams.id);
+        Vehicle* vehicle = GetEntity<Vehicle>(EntityId::FromUnderlying(vehicleSoundParams.id));
         if (vehicle != nullptr)
         {
             UpdateSound<SoundType::TrackNoises>(
@@ -2097,7 +2097,7 @@ void Vehicle::TrainReadyToDepart(uint8_t num_peeps_on_train, uint8_t num_used_se
     if (curRide->mode == RideMode::ForwardRotation || curRide->mode == RideMode::BackwardRotation)
     {
         uint8_t seat = ((-Pitch) / 8) & 0xF;
-        if (peep[seat] != SPRITE_INDEX_NULL)
+        if (!peep[seat].IsNull())
         {
             curRide->stations[current_station].TrainAtStation = RideStation::NO_TRAIN;
             SetState(Vehicle::Status::UnloadingPassengers);
@@ -2119,7 +2119,7 @@ void Vehicle::TrainReadyToDepart(uint8_t num_peeps_on_train, uint8_t num_used_se
     SetState(Vehicle::Status::WaitingForPassengers);
 }
 
-static std::optional<uint32_t> ride_get_train_index_from_vehicle(Ride* ride, uint16_t spriteIndex)
+static std::optional<uint32_t> ride_get_train_index_from_vehicle(Ride* ride, EntityId spriteIndex)
 {
     uint32_t trainIndex = 0;
     while (ride->vehicles[trainIndex] != spriteIndex)
@@ -2384,7 +2384,7 @@ void Vehicle::UpdateWaitingToDepart()
         if (curRide->mode == RideMode::ForwardRotation || curRide->mode == RideMode::BackwardRotation)
         {
             uint8_t seat = ((-Pitch) >> 3) & 0xF;
-            if (peep[seat * 2] == SPRITE_INDEX_NULL)
+            if (peep[seat * 2].IsNull())
             {
                 if (num_peeps == 0)
                 {
@@ -2579,7 +2579,7 @@ struct rct_synchronised_vehicle
 {
     RideId ride_id;
     StationIndex stationIndex;
-    uint16_t vehicle_id;
+    EntityId vehicle_id;
 };
 
 constexpr int32_t SYNCHRONISED_VEHICLE_COUNT = 16;
@@ -2627,7 +2627,7 @@ static bool try_add_synchronised_station(const CoordsXYZ& coords)
     rct_synchronised_vehicle* sv = _lastSynchronisedVehicle;
     sv->ride_id = rideIndex;
     sv->stationIndex = stationIndex;
-    sv->vehicle_id = SPRITE_INDEX_NULL;
+    sv->vehicle_id = EntityId::GetNull();
     _lastSynchronisedVehicle++;
 
     /* Ride vehicles are not on the track (e.g. ride is/was under
@@ -2803,7 +2803,7 @@ static bool ride_station_can_depart_synchronised(const Ride& ride, StationIndex
                     }
                 }
                 // There is no vehicle waiting at this station to sync with.
-                if (sv->vehicle_id == SPRITE_INDEX_NULL)
+                if (sv->vehicle_id.IsNull())
                 {
                     // Check conditions for departing without all stations being in sync.
                     if (_lastSynchronisedVehicle > &_synchronisedVehicles[1])
@@ -3528,8 +3528,8 @@ void Vehicle::UpdateCrashSetup()
     int32_t edx = velocity >> 10;
 
     Vehicle* lastVehicle = this;
-    uint16_t spriteId = sprite_index;
-    for (Vehicle* trainVehicle; spriteId != SPRITE_INDEX_NULL; spriteId = trainVehicle->next_vehicle_on_train)
+    auto spriteId = sprite_index;
+    for (Vehicle* trainVehicle; !spriteId.IsNull(); spriteId = trainVehicle->next_vehicle_on_train)
     {
         trainVehicle = GetEntity<Vehicle>(spriteId);
         if (trainVehicle == nullptr)
@@ -3999,12 +3999,12 @@ void Vehicle::UpdateUnloadingPassengers()
     if (curRide->mode == RideMode::ForwardRotation || curRide->mode == RideMode::BackwardRotation)
     {
         uint8_t seat = ((-Pitch) >> 3) & 0xF;
-        if (restraints_position == 255 && (peep[seat * 2] != SPRITE_INDEX_NULL))
+        if (restraints_position == 255 && !peep[seat * 2].IsNull())
         {
             next_free_seat -= 2;
 
             auto firstGuest = GetEntity<Guest>(peep[seat * 2]);
-            peep[seat * 2] = SPRITE_INDEX_NULL;
+            peep[seat * 2] = EntityId::GetNull();
 
             if (firstGuest != nullptr)
             {
@@ -4013,7 +4013,7 @@ void Vehicle::UpdateUnloadingPassengers()
             }
 
             auto secondGuest = GetEntity<Guest>(peep[seat * 2 + 1]);
-            peep[seat * 2 + 1] = SPRITE_INDEX_NULL;
+            peep[seat * 2 + 1] = EntityId::GetNull();
 
             if (secondGuest != nullptr)
             {
@@ -6164,7 +6164,7 @@ Vehicle* Vehicle::TrainHead() const
         prevVehicle = GetEntity<Vehicle>(vehicle->prev_vehicle_on_ride);
         if (prevVehicle == nullptr)
             return nullptr;
-        if (prevVehicle->next_vehicle_on_train == SPRITE_INDEX_NULL)
+        if (prevVehicle->next_vehicle_on_train.IsNull())
             break;
 
         vehicle = prevVehicle;
@@ -6176,15 +6176,16 @@ Vehicle* Vehicle::TrainHead() const
 Vehicle* Vehicle::TrainTail() const
 {
     const Vehicle* vehicle = this;
-    uint16_t spriteIndex;
 
-    while ((spriteIndex = vehicle->next_vehicle_on_train) != SPRITE_INDEX_NULL)
+    EntityId spriteIndex = vehicle->next_vehicle_on_train;
+    while (!spriteIndex.IsNull())
     {
         vehicle = GetEntity<Vehicle>(spriteIndex);
         if (vehicle == nullptr)
         {
             return const_cast<Vehicle*>(this);
         }
+        spriteIndex = vehicle->next_vehicle_on_train;
     }
 
     return const_cast<Vehicle*>(vehicle);
@@ -6249,8 +6250,7 @@ int32_t Vehicle::UpdateMotionDodgems()
         }
     }
 
-    uint16_t collideSprite = SPRITE_INDEX_NULL;
-
+    auto collideSprite = EntityId::GetNull();
     if (dodgems_collision_direction != 0)
     {
         uint8_t oldCollisionDirection = dodgems_collision_direction & 0x1E;
@@ -6384,14 +6384,15 @@ static bool wouldCollideWithDodgemsTrackEdge(
         || coords.x + dodgemsCarRadius > rideRight || coords.y + dodgemsCarRadius > rideBottom;
 }
 
-bool Vehicle::DodgemsCarWouldCollideAt(const CoordsXY& coords, uint16_t* collidedWith) const
+// TODO: Return optional<EntityId>
+bool Vehicle::DodgemsCarWouldCollideAt(const CoordsXY& coords, EntityId* collidedWith) const
 {
     auto trackType = GetTrackType();
 
     if (wouldCollideWithDodgemsTrackEdge(coords, TrackLocation, trackType, (var_44 * 30) >> 9))
     {
         if (collidedWith != nullptr)
-            *collidedWith = SPRITE_INDEX_NULL;
+            *collidedWith = EntityId::GetNull();
         return true;
     }
 
@@ -6979,7 +6980,7 @@ void Vehicle::UpdateSpinningCar()
             spinningInertia += 6;
             spinSpeed = dword_F64E08 >> spinningInertia;
             // Alternate the spin direction (roughly). Perhaps in future save a value to the track
-            if (sprite_index & 1)
+            if (sprite_index.ToUnderlying() & 1)
             {
                 spin_speed -= spinSpeed;
             }
@@ -7331,7 +7332,7 @@ void Vehicle::UpdateSceneryDoor() const
     int32_t direction = (GetTrackDirection() + trackCoordinates->rotation_end) & 3;
 
     AnimateSceneryDoor<false>(
-        { wallCoords, static_cast<Direction>(direction) }, TrackLocation, next_vehicle_on_train == SPRITE_INDEX_NULL);
+        { wallCoords, static_cast<Direction>(direction) }, TrackLocation, next_vehicle_on_train.IsNull());
 }
 
 template<bool isBackwards> static void AnimateLandscapeDoor(TrackElement* trackElement, bool isLastVehicle)
@@ -7368,7 +7369,7 @@ void Vehicle::UpdateLandscapeDoor() const
     auto* tileElement = map_get_track_element_at_from_ride(coords, ride);
     if (tileElement != nullptr && tileElement->GetType() == TileElementType::Track)
     {
-        AnimateLandscapeDoor<false>(tileElement->AsTrack(), next_vehicle_on_train == SPRITE_INDEX_NULL);
+        AnimateLandscapeDoor<false>(tileElement->AsTrack(), next_vehicle_on_train.IsNull());
     }
 }
 
@@ -7426,8 +7427,7 @@ void Vehicle::UpdateSceneryDoorBackwards() const
     int32_t direction = (GetTrackDirection() + trackCoordinates->rotation_begin) & 3;
     direction = direction_reverse(direction);
 
-    AnimateSceneryDoor<true>(
-        { wallCoords, static_cast<Direction>(direction) }, TrackLocation, next_vehicle_on_train == SPRITE_INDEX_NULL);
+    AnimateSceneryDoor<true>({ wallCoords, static_cast<Direction>(direction) }, TrackLocation, next_vehicle_on_train.IsNull());
 }
 
 void Vehicle::UpdateLandscapeDoorBackwards() const
@@ -7442,7 +7442,7 @@ void Vehicle::UpdateLandscapeDoorBackwards() const
     auto* tileElement = map_get_track_element_at_from_ride(coords, ride);
     if (tileElement != nullptr && tileElement->GetType() == TileElementType::Track)
     {
-        AnimateLandscapeDoor<true>(tileElement->AsTrack(), next_vehicle_on_train == SPRITE_INDEX_NULL);
+        AnimateLandscapeDoor<true>(tileElement->AsTrack(), next_vehicle_on_train.IsNull());
     }
 }
 
@@ -7532,7 +7532,7 @@ void Vehicle::UpdateReverserCarBogies()
  * @param z (dx)
  * @param otherVehicleIndex (bp)
  */
-bool Vehicle::UpdateMotionCollisionDetection(const CoordsXYZ& loc, uint16_t* otherVehicleIndex)
+bool Vehicle::UpdateMotionCollisionDetection(const CoordsXYZ& loc, EntityId* otherVehicleIndex)
 {
     if (HasUpdateFlag(VEHICLE_UPDATE_FLAG_COLLISION_DISABLED))
         return false;
@@ -7861,7 +7861,7 @@ bool Vehicle::UpdateTrackMotionForwardsGetNewTrack(uint16_t trackType, Ride* cur
 
     if (tileElement->AsTrack()->IsBlockStart())
     {
-        if (next_vehicle_on_train == SPRITE_INDEX_NULL)
+        if (next_vehicle_on_train.IsNull())
         {
             tileElement->AsTrack()->SetBlockBrakeClosed(true);
             if (trackType == TrackElemType::BlockBrakes || trackType == TrackElemType::EndStation)
@@ -8025,7 +8025,7 @@ bool Vehicle::UpdateTrackMotionForwardsGetNewTrack(uint16_t trackType, Ride* cur
  */
 bool Vehicle::UpdateTrackMotionForwards(rct_ride_entry_vehicle* vehicleEntry, Ride* curRide, rct_ride_entry* rideEntry)
 {
-    uint16_t otherVehicleIndex = SPRITE_INDEX_NULL;
+    EntityId otherVehicleIndex = EntityId::GetNull();
 loc_6DAEB9:
     auto trackType = GetTrackType();
     if (trackType == TrackElemType::HeartLineTransferUp || trackType == TrackElemType::HeartLineTransferDown)
@@ -8370,7 +8370,7 @@ bool Vehicle::UpdateTrackMotionBackwardsGetNewTrack(uint16_t trackType, Ride* cu
     {
         if (_vehicleVelocityF64E08 < 0)
         {
-            if (next_vehicle_on_train == SPRITE_INDEX_NULL)
+            if (next_vehicle_on_train.IsNull())
             {
                 trackType = tileElement->AsTrack()->GetTrackType();
                 const auto& ted = GetTrackElementDescriptor(trackType);
@@ -8387,7 +8387,7 @@ bool Vehicle::UpdateTrackMotionBackwardsGetNewTrack(uint16_t trackType, Ride* cu
         if (HasUpdateFlag(VEHICLE_UPDATE_FLAG_ON_LIFT_HILL))
         {
             ClearUpdateFlag(VEHICLE_UPDATE_FLAG_ON_LIFT_HILL);
-            if (next_vehicle_on_train == SPRITE_INDEX_NULL)
+            if (next_vehicle_on_train.IsNull())
             {
                 if (_vehicleVelocityF64E08 < 0)
                 {
@@ -8419,7 +8419,7 @@ bool Vehicle::UpdateTrackMotionBackwardsGetNewTrack(uint16_t trackType, Ride* cu
  */
 bool Vehicle::UpdateTrackMotionBackwards(rct_ride_entry_vehicle* vehicleEntry, Ride* curRide, rct_ride_entry* rideEntry)
 {
-    uint16_t otherVehicleIndex = SPRITE_INDEX_NULL;
+    EntityId otherVehicleIndex = EntityId::GetNull();
 
     while (true)
     {
@@ -8566,7 +8566,7 @@ bool Vehicle::UpdateTrackMotionBackwards(rct_ride_entry_vehicle* vehicleEntry, R
  */
 void Vehicle::UpdateTrackMotionMiniGolfVehicle(Ride* curRide, rct_ride_entry* rideEntry, rct_ride_entry_vehicle* vehicleEntry)
 {
-    uint16_t otherVehicleIndex = SPRITE_INDEX_NULL;
+    EntityId otherVehicleIndex = EntityId::GetNull();
     TileElement* tileElement = nullptr;
     CoordsXYZ trackPos;
     int32_t direction{};
@@ -8935,7 +8935,7 @@ loc_6DCA9A:
     if (HasUpdateFlag(VEHICLE_UPDATE_FLAG_ON_LIFT_HILL))
     {
         ClearUpdateFlag(VEHICLE_UPDATE_FLAG_ON_LIFT_HILL);
-        if (next_vehicle_on_train == SPRITE_INDEX_NULL)
+        if (next_vehicle_on_train.IsNull())
         {
             if (_vehicleVelocityF64E08 < 0)
             {
@@ -8981,7 +8981,7 @@ loc_6DCC2C:
     {
         if (_vehicleVelocityF64E08 >= 0)
         {
-            otherVehicleIndex = var_44;
+            otherVehicleIndex = EntityId::FromUnderlying(var_44); // Possibly wrong?.
             if (UpdateMotionCollisionDetection(trackPos, &otherVehicleIndex))
             {
                 goto loc_6DCD6B;
@@ -9374,8 +9374,8 @@ int32_t Vehicle::UpdateTrackMotion(int32_t* outStation)
     // backwards.
     _vehicleFrontVehicle = vehicle;
 
-    uint16_t spriteId = vehicle->sprite_index;
-    while (spriteId != SPRITE_INDEX_NULL)
+    auto spriteId = vehicle->sprite_index;
+    while (!spriteId.IsNull())
     {
         Vehicle* car = GetEntity<Vehicle>(spriteId);
         if (car == nullptr)
diff --git a/src/openrct2/ride/Vehicle.h b/src/openrct2/ride/Vehicle.h
index 7977c65153..d0ba04f143 100644
--- a/src/openrct2/ride/Vehicle.h
+++ b/src/openrct2/ride/Vehicle.h
@@ -9,6 +9,7 @@
 
 #pragma once
 
+#include "../Identifiers.h"
 #include "../audio/audio.h"
 #include "../common.h"
 #include "../entity/EntityBase.h"
@@ -120,13 +121,13 @@ struct Vehicle : EntityBase
     };
     uint16_t TrackTypeAndDirection;
     CoordsXYZ TrackLocation;
-    uint16_t next_vehicle_on_train;
+    EntityId next_vehicle_on_train;
 
     // The previous vehicle on the same train or the last vehicle on the previous or only train.
-    uint16_t prev_vehicle_on_ride;
+    EntityId prev_vehicle_on_ride;
 
     // The next vehicle on the same train or the first vehicle on the next or only train
-    uint16_t next_vehicle_on_ride;
+    EntityId next_vehicle_on_ride;
 
     uint16_t var_44;
     uint16_t mass;
@@ -150,7 +151,7 @@ struct Vehicle : EntityBase
     };
     Status status;
     uint8_t sub_state;
-    uint16_t peep[32];
+    EntityId peep[32];
     uint8_t peep_tshirt_colours[32];
     uint8_t num_seats;
     uint8_t num_peeps;
@@ -173,7 +174,7 @@ struct Vehicle : EntityBase
         uint16_t var_C0;
         int16_t crash_y;
         uint16_t time_waiting;
-        uint16_t cable_lift_target;
+        EntityId cable_lift_target;
     };
     uint8_t speed;
     uint8_t powered_acceleration;
@@ -216,7 +217,7 @@ struct Vehicle : EntityBase
     void SetState(Vehicle::Status vehicleStatus, uint8_t subState = 0);
     bool IsGhost() const;
     void UpdateSoundParams(std::vector<OpenRCT2::Audio::VehicleSoundParams>& vehicleSoundParamsList) const;
-    bool DodgemsCarWouldCollideAt(const CoordsXY& coords, uint16_t* spriteId) const;
+    bool DodgemsCarWouldCollideAt(const CoordsXY& coords, EntityId* spriteId) const;
     int32_t UpdateTrackMotion(int32_t* outStation);
     int32_t CableLiftUpdateTrackMotion();
     GForces GetGForces() const;
@@ -361,7 +362,7 @@ private:
     void UpdateTrackMotionMiniGolfVehicle(Ride* curRide, rct_ride_entry* rideEntry, rct_ride_entry_vehicle* vehicleEntry);
     bool UpdateTrackMotionForwardsGetNewTrack(uint16_t trackType, Ride* curRide, rct_ride_entry* rideEntry);
     bool UpdateTrackMotionBackwardsGetNewTrack(uint16_t trackType, Ride* curRide, uint16_t* progress);
-    bool UpdateMotionCollisionDetection(const CoordsXYZ& loc, uint16_t* otherVehicleIndex);
+    bool UpdateMotionCollisionDetection(const CoordsXYZ& loc, EntityId* otherVehicleIndex);
     void UpdateGoKartAttemptSwitchLanes();
     void UpdateSceneryDoor() const;
     void UpdateSceneryDoorBackwards() const;
@@ -514,7 +515,7 @@ enum
 #define VEHICLE_SEAT_PAIR_FLAG 0x80
 #define VEHICLE_SEAT_NUM_MASK 0x7F
 
-Vehicle* try_get_vehicle(uint16_t spriteIndex);
+Vehicle* try_get_vehicle(EntityId spriteIndex);
 void vehicle_update_all();
 void vehicle_sounds_update();
 
diff --git a/src/openrct2/ride/thrill/3dCinema.cpp b/src/openrct2/ride/thrill/3dCinema.cpp
index ce8ed9cbd5..5be7aadac0 100644
--- a/src/openrct2/ride/thrill/3dCinema.cpp
+++ b/src/openrct2/ride/thrill/3dCinema.cpp
@@ -25,7 +25,7 @@ static void Paint3dCinemaDome(
     if (rideEntry == nullptr)
         return;
 
-    if (ride.lifecycle_flags & RIDE_LIFECYCLE_ON_TRACK && ride.vehicles[0] != SPRITE_INDEX_NULL)
+    if (ride.lifecycle_flags & RIDE_LIFECYCLE_ON_TRACK && !ride.vehicles[0].IsNull())
     {
         session.InteractionType = ViewportInteractionItem::Entity;
         session.CurrentlyDrawnItem = GetEntity<Vehicle>(ride.vehicles[0]);
diff --git a/src/openrct2/ride/thrill/SwingingShip.cpp b/src/openrct2/ride/thrill/SwingingShip.cpp
index 599ba55867..b68fecc534 100644
--- a/src/openrct2/ride/thrill/SwingingShip.cpp
+++ b/src/openrct2/ride/thrill/SwingingShip.cpp
@@ -101,7 +101,7 @@ static void PaintSwingingShipStructure(
         return;
 
     Vehicle* vehicle = nullptr;
-    if (ride.lifecycle_flags & RIDE_LIFECYCLE_ON_TRACK && ride.vehicles[0] != SPRITE_INDEX_NULL)
+    if (ride.lifecycle_flags & RIDE_LIFECYCLE_ON_TRACK && !ride.vehicles[0].IsNull())
     {
         vehicle = GetEntity<Vehicle>(ride.vehicles[0]);
         session.InteractionType = ViewportInteractionItem::Entity;
diff --git a/src/openrct2/ride/thrill/Twist.cpp b/src/openrct2/ride/thrill/Twist.cpp
index adb0af3980..bff5fa967e 100644
--- a/src/openrct2/ride/thrill/Twist.cpp
+++ b/src/openrct2/ride/thrill/Twist.cpp
@@ -34,7 +34,7 @@ static void paint_twist_structure(
 
     height += 7;
 
-    if (ride.lifecycle_flags & RIDE_LIFECYCLE_ON_TRACK && ride.vehicles[0] != SPRITE_INDEX_NULL)
+    if (ride.lifecycle_flags & RIDE_LIFECYCLE_ON_TRACK && !ride.vehicles[0].IsNull())
     {
         vehicle = GetEntity<Vehicle>(ride.vehicles[0]);
 
diff --git a/src/openrct2/scripting/ScriptEngine.cpp b/src/openrct2/scripting/ScriptEngine.cpp
index 64ba4bbc3a..c3da70094e 100644
--- a/src/openrct2/scripting/ScriptEngine.cpp
+++ b/src/openrct2/scripting/ScriptEngine.cpp
@@ -900,9 +900,9 @@ DukValue ScriptEngine::GameActionResultToDuk(const GameAction& action, const Gam
         if (result.Error == GameActions::Status::Ok)
         {
             const auto actionResult = result.GetData<StaffHireNewActionResult>();
-            if (actionResult.StaffEntityId != SPRITE_INDEX_NULL)
+            if (!actionResult.StaffEntityId.IsNull())
             {
-                obj.Set("peep", actionResult.StaffEntityId);
+                obj.Set("peep", actionResult.StaffEntityId.ToUnderlying());
             }
         }
     }
diff --git a/src/openrct2/scripting/bindings/entity/ScEntity.hpp b/src/openrct2/scripting/bindings/entity/ScEntity.hpp
index cae3562a8d..7b4d9b03ad 100644
--- a/src/openrct2/scripting/bindings/entity/ScEntity.hpp
+++ b/src/openrct2/scripting/bindings/entity/ScEntity.hpp
@@ -29,10 +29,10 @@ namespace OpenRCT2::Scripting
     class ScEntity
     {
     protected:
-        uint16_t _id = SPRITE_INDEX_NULL;
+        EntityId _id{ EntityId::GetNull() };
 
     public:
-        ScEntity(uint16_t id)
+        ScEntity(EntityId id)
             : _id(id)
         {
         }
@@ -41,7 +41,7 @@ namespace OpenRCT2::Scripting
         int32_t id_get() const
         {
             auto entity = GetEntity();
-            return entity != nullptr ? entity->sprite_index : 0;
+            return entity != nullptr ? entity->sprite_index.ToUnderlying() : EntityId::GetNull().ToUnderlying();
         }
 
         std::string type_get() const
diff --git a/src/openrct2/scripting/bindings/entity/ScGuest.cpp b/src/openrct2/scripting/bindings/entity/ScGuest.cpp
index fc5e715e93..bfbbc4c557 100644
--- a/src/openrct2/scripting/bindings/entity/ScGuest.cpp
+++ b/src/openrct2/scripting/bindings/entity/ScGuest.cpp
@@ -15,7 +15,7 @@
 
 namespace OpenRCT2::Scripting
 {
-    ScGuest::ScGuest(uint16_t id)
+    ScGuest::ScGuest(EntityId id)
         : ScPeep(id)
     {
     }
diff --git a/src/openrct2/scripting/bindings/entity/ScGuest.hpp b/src/openrct2/scripting/bindings/entity/ScGuest.hpp
index e387cb22d9..3c25b30109 100644
--- a/src/openrct2/scripting/bindings/entity/ScGuest.hpp
+++ b/src/openrct2/scripting/bindings/entity/ScGuest.hpp
@@ -18,7 +18,7 @@ namespace OpenRCT2::Scripting
     class ScGuest : public ScPeep
     {
     public:
-        ScGuest(uint16_t id);
+        ScGuest(EntityId id);
 
         static void Register(duk_context* ctx);
 
diff --git a/src/openrct2/scripting/bindings/entity/ScLitter.cpp b/src/openrct2/scripting/bindings/entity/ScLitter.cpp
index 70f3118f7e..10cd481357 100644
--- a/src/openrct2/scripting/bindings/entity/ScLitter.cpp
+++ b/src/openrct2/scripting/bindings/entity/ScLitter.cpp
@@ -30,7 +30,7 @@ namespace OpenRCT2::Scripting
         { "empty_bowl_blue", Litter::Type::EmptyBowlBlue },
     });
 
-    ScLitter::ScLitter(uint16_t Id)
+    ScLitter::ScLitter(EntityId Id)
         : ScEntity(Id)
     {
     }
diff --git a/src/openrct2/scripting/bindings/entity/ScLitter.hpp b/src/openrct2/scripting/bindings/entity/ScLitter.hpp
index 41b8b9f1e4..bc5ef1e82c 100644
--- a/src/openrct2/scripting/bindings/entity/ScLitter.hpp
+++ b/src/openrct2/scripting/bindings/entity/ScLitter.hpp
@@ -20,7 +20,7 @@ namespace OpenRCT2::Scripting
     class ScLitter : public ScEntity
     {
     public:
-        ScLitter(uint16_t Id);
+        ScLitter(EntityId Id);
 
         static void Register(duk_context* ctx);
 
diff --git a/src/openrct2/scripting/bindings/entity/ScPeep.hpp b/src/openrct2/scripting/bindings/entity/ScPeep.hpp
index 96173a3a29..d371e1a416 100644
--- a/src/openrct2/scripting/bindings/entity/ScPeep.hpp
+++ b/src/openrct2/scripting/bindings/entity/ScPeep.hpp
@@ -46,7 +46,7 @@ namespace OpenRCT2::Scripting
     class ScPeep : public ScEntity
     {
     public:
-        ScPeep(uint16_t id)
+        ScPeep(EntityId id)
             : ScEntity(id)
         {
         }
diff --git a/src/openrct2/scripting/bindings/entity/ScStaff.cpp b/src/openrct2/scripting/bindings/entity/ScStaff.cpp
index 5f9b13bd10..4b57f53120 100644
--- a/src/openrct2/scripting/bindings/entity/ScStaff.cpp
+++ b/src/openrct2/scripting/bindings/entity/ScStaff.cpp
@@ -15,7 +15,7 @@
 
 namespace OpenRCT2::Scripting
 {
-    ScStaff::ScStaff(uint16_t Id)
+    ScStaff::ScStaff(EntityId Id)
         : ScPeep(Id)
     {
     }
diff --git a/src/openrct2/scripting/bindings/entity/ScStaff.hpp b/src/openrct2/scripting/bindings/entity/ScStaff.hpp
index 0102144075..d1c322cd8d 100644
--- a/src/openrct2/scripting/bindings/entity/ScStaff.hpp
+++ b/src/openrct2/scripting/bindings/entity/ScStaff.hpp
@@ -18,7 +18,7 @@ namespace OpenRCT2::Scripting
     class ScStaff : public ScPeep
     {
     public:
-        ScStaff(uint16_t Id);
+        ScStaff(EntityId Id);
 
         static void Register(duk_context* ctx);
 
diff --git a/src/openrct2/scripting/bindings/entity/ScVehicle.cpp b/src/openrct2/scripting/bindings/entity/ScVehicle.cpp
index d2f974335a..bf564ab0d2 100644
--- a/src/openrct2/scripting/bindings/entity/ScVehicle.cpp
+++ b/src/openrct2/scripting/bindings/entity/ScVehicle.cpp
@@ -49,7 +49,7 @@ namespace OpenRCT2::Scripting
         { "stopped_by_block_brake", Vehicle::Status::StoppedByBlockBrakes },
     });
 
-    ScVehicle::ScVehicle(uint16_t id)
+    ScVehicle::ScVehicle(EntityId id)
         : ScEntity(id)
     {
     }
@@ -172,9 +172,9 @@ namespace OpenRCT2::Scripting
         auto vehicle = GetVehicle();
         if (vehicle != nullptr)
         {
-            if (vehicle->next_vehicle_on_train != SPRITE_INDEX_NULL)
+            if (!vehicle->next_vehicle_on_train.IsNull())
             {
-                return ToDuk<int32_t>(ctx, vehicle->next_vehicle_on_train);
+                return ToDuk<int32_t>(ctx, vehicle->next_vehicle_on_train.ToUnderlying());
             }
         }
         return ToDuk(ctx, nullptr);
@@ -187,11 +187,11 @@ namespace OpenRCT2::Scripting
         {
             if (value.type() == DukValue::Type::NUMBER)
             {
-                vehicle->next_vehicle_on_train = static_cast<uint16_t>(value.as_int());
+                vehicle->next_vehicle_on_train = EntityId::FromUnderlying(value.as_int());
             }
             else
             {
-                vehicle->next_vehicle_on_train = SPRITE_INDEX_NULL;
+                vehicle->next_vehicle_on_train = EntityId::GetNull();
             }
         }
     }
@@ -199,7 +199,7 @@ namespace OpenRCT2::Scripting
     uint16_t ScVehicle::previousCarOnRide_get() const
     {
         auto vehicle = GetVehicle();
-        return vehicle != nullptr ? vehicle->prev_vehicle_on_ride : 0;
+        return vehicle != nullptr ? vehicle->prev_vehicle_on_ride.ToUnderlying() : EntityId::GetNull().ToUnderlying();
     }
     void ScVehicle::previousCarOnRide_set(uint16_t value)
     {
@@ -207,14 +207,14 @@ namespace OpenRCT2::Scripting
         auto vehicle = GetVehicle();
         if (vehicle != nullptr)
         {
-            vehicle->prev_vehicle_on_ride = value;
+            vehicle->prev_vehicle_on_ride = EntityId::FromUnderlying(value);
         }
     }
 
     uint16_t ScVehicle::nextCarOnRide_get() const
     {
         auto vehicle = GetVehicle();
-        return vehicle != nullptr ? vehicle->next_vehicle_on_ride : 0;
+        return vehicle != nullptr ? vehicle->next_vehicle_on_ride.ToUnderlying() : EntityId::GetNull().ToUnderlying();
     }
     void ScVehicle::nextCarOnRide_set(uint16_t value)
     {
@@ -222,7 +222,7 @@ namespace OpenRCT2::Scripting
         auto vehicle = GetVehicle();
         if (vehicle != nullptr)
         {
-            vehicle->next_vehicle_on_ride = value;
+            vehicle->next_vehicle_on_ride = EntityId::FromUnderlying(value);
         }
     }
 
@@ -423,13 +423,13 @@ namespace OpenRCT2::Scripting
             for (size_t i = 0; i < std::size(vehicle->peep); i++)
             {
                 auto peep = vehicle->peep[i];
-                if (peep == SPRITE_INDEX_NULL)
+                if (peep.IsNull())
                 {
                     result.push_back(ToDuk(ctx, nullptr));
                 }
                 else
                 {
-                    result.push_back(ToDuk<int32_t>(ctx, peep));
+                    result.push_back(ToDuk<int32_t>(ctx, peep.ToUnderlying()));
                     len = i + 1;
                 }
             }
diff --git a/src/openrct2/scripting/bindings/entity/ScVehicle.hpp b/src/openrct2/scripting/bindings/entity/ScVehicle.hpp
index c98cd5b3dc..743887f1c3 100644
--- a/src/openrct2/scripting/bindings/entity/ScVehicle.hpp
+++ b/src/openrct2/scripting/bindings/entity/ScVehicle.hpp
@@ -19,7 +19,7 @@ namespace OpenRCT2::Scripting
     class ScVehicle : public ScEntity
     {
     public:
-        ScVehicle(uint16_t id);
+        ScVehicle(EntityId id);
 
         static void Register(duk_context* ctx);
 
diff --git a/src/openrct2/scripting/bindings/ride/ScRide.cpp b/src/openrct2/scripting/bindings/ride/ScRide.cpp
index 6e83c7d850..3150331a03 100644
--- a/src/openrct2/scripting/bindings/ride/ScRide.cpp
+++ b/src/openrct2/scripting/bindings/ride/ScRide.cpp
@@ -191,7 +191,10 @@ namespace OpenRCT2::Scripting
         auto ride = GetRide();
         if (ride != nullptr)
         {
-            result.insert(result.begin(), std::begin(ride->vehicles), std::begin(ride->vehicles) + ride->num_vehicles);
+            for (auto& veh : ride->vehicles)
+            {
+                result.push_back(veh.ToUnderlying());
+            }
         }
         return result;
     }
diff --git a/src/openrct2/scripting/bindings/world/ScMap.cpp b/src/openrct2/scripting/bindings/world/ScMap.cpp
index ef562464c9..c811d24c30 100644
--- a/src/openrct2/scripting/bindings/world/ScMap.cpp
+++ b/src/openrct2/scripting/bindings/world/ScMap.cpp
@@ -87,7 +87,7 @@ namespace OpenRCT2::Scripting
     {
         if (id >= 0 && id < MAX_ENTITIES)
         {
-            auto spriteId = static_cast<uint16_t>(id);
+            auto spriteId = EntityId::FromUnderlying(id);
             auto sprite = GetEntity(spriteId);
             if (sprite != nullptr && sprite->Type != EntityType::Null)
             {
@@ -112,7 +112,7 @@ namespace OpenRCT2::Scripting
         {
             for (auto trainHead : TrainManager::View())
             {
-                for (auto carId = trainHead->sprite_index; carId != SPRITE_INDEX_NULL;)
+                for (auto carId = trainHead->sprite_index; !carId.IsNull();)
                 {
                     auto car = GetEntity<Vehicle>(carId);
                     result.push_back(GetObjectAsDukValue(_context, std::make_shared<ScVehicle>(carId)));
diff --git a/src/openrct2/title/TitleSequence.cpp b/src/openrct2/title/TitleSequence.cpp
index a5f9df4b97..600f876d03 100644
--- a/src/openrct2/title/TitleSequence.cpp
+++ b/src/openrct2/title/TitleSequence.cpp
@@ -371,7 +371,7 @@ static std::vector<TitleCommand> LegacyScriptRead(const std::vector<uint8_t>& sc
             else if (_stricmp(token, "FOLLOW") == 0)
             {
                 command.Type = TitleScript::Follow;
-                command.SpriteIndex = atoi(part1) & 0xFFFF;
+                command.SpriteIndex = EntityId::FromUnderlying(atoi(part1) & 0xFFFF);
                 safe_strcpy(command.SpriteName, part2, USER_STRING_MAX_LENGTH);
             }
             else if (_stricmp(token, "WAIT") == 0)
diff --git a/src/openrct2/title/TitleSequence.h b/src/openrct2/title/TitleSequence.h
index 62c64d1593..893f23e4cc 100644
--- a/src/openrct2/title/TitleSequence.h
+++ b/src/openrct2/title/TitleSequence.h
@@ -32,7 +32,7 @@ struct TitleCommand
         uint8_t Zoom;      // ZOOM
         struct             // FOLLOW
         {
-            uint16_t SpriteIndex;
+            EntityId SpriteIndex;
             utf8 SpriteName[USER_STRING_MAX_LENGTH];
         };
         uint8_t Speed;                                // SPEED