diff --git a/Content.Client/Options/UI/Tabs/MiscTab.xaml b/Content.Client/Options/UI/Tabs/MiscTab.xaml
index c1733e209d..8a73aa9aec 100644
--- a/Content.Client/Options/UI/Tabs/MiscTab.xaml
+++ b/Content.Client/Options/UI/Tabs/MiscTab.xaml
@@ -9,6 +9,8 @@
                        StyleClasses="LabelKeyText"/>
                 <ui:OptionDropDown Name="DropDownHudTheme" Title="{Loc 'ui-options-hud-theme'}" />
                 <ui:OptionDropDown Name="DropDownHudLayout" Title="{Loc 'ui-options-hud-layout'}" />
+                <!-- EE - chat stacking -->
+                <ui:OptionDropDown Name="ChatStackLastLines" Title="{Loc 'ui-options-chatstack'}" />
                 <Label Text="{Loc 'ui-options-general-discord'}"
                        StyleClasses="LabelKeyText"/>
                 <CheckBox Name="DiscordRich" Text="{Loc 'ui-options-discordrich'}" />
diff --git a/Content.Client/Options/UI/Tabs/MiscTab.xaml.cs b/Content.Client/Options/UI/Tabs/MiscTab.xaml.cs
index 79000af58c..b254dd401b 100644
--- a/Content.Client/Options/UI/Tabs/MiscTab.xaml.cs
+++ b/Content.Client/Options/UI/Tabs/MiscTab.xaml.cs
@@ -1,6 +1,7 @@
 using System.Linq;
 using Content.Client.UserInterface.Screens;
 using Content.Shared.CCVar;
+using Content.Shared._EE.CCVars; // EE - chat stack
 using Content.Shared.HUD;
 using Robust.Client.AutoGenerated;
 using Robust.Client.Player;
@@ -36,12 +37,22 @@ public sealed partial class MiscTab : Control
             layoutEntries.Add(new OptionDropDownCVar<string>.ValueOption(layout.ToString()!, Loc.GetString($"ui-options-hud-layout-{layout.ToString()!.ToLower()}")));
         }
 
+        // EE - Chat stacking options for how far back in the chat to stack.
+        var chatStackEntries = new List<OptionDropDownCVar<int>.ValueOption>();
+        for (var option = 0; option <= 3; option++)
+        {
+            chatStackEntries.Add(
+                new OptionDropDownCVar<int>.ValueOption(option, Loc.GetString("ui-options-chatstack-count", ("count", option))));
+        }
+        // End EE - Chat stacking
+
         // Channel can be null in replays so.
         // ReSharper disable once ConditionalAccessQualifierIsNonNullableAccordingToAPIContract
         ShowOocPatronColor.Visible = _playerManager.LocalSession?.Channel?.UserData.PatronTier is { };
 
         Control.AddOptionDropDown(CVars.InterfaceTheme, DropDownHudTheme, themeEntries);
         Control.AddOptionDropDown(CCVars.UILayout, DropDownHudLayout, layoutEntries);
+        Control.AddOptionDropDown<int>(EECVars.ChatStackLastLines, ChatStackLastLines, chatStackEntries); // EE - Chat stacking
 
         Control.AddOptionCheckBox(CVars.DiscordEnabled, DiscordRich);
         Control.AddOptionCheckBox(CCVars.ShowOocPatronColor, ShowOocPatronColor);
diff --git a/Content.Client/UserInterface/Systems/Chat/Widgets/ChatBox.xaml.cs b/Content.Client/UserInterface/Systems/Chat/Widgets/ChatBox.xaml.cs
index f6c4cf407d..e7af05530f 100644
--- a/Content.Client/UserInterface/Systems/Chat/Widgets/ChatBox.xaml.cs
+++ b/Content.Client/UserInterface/Systems/Chat/Widgets/ChatBox.xaml.cs
@@ -1,13 +1,14 @@
 using Content.Client.UserInterface.Systems.Chat.Controls;
+using Content.Shared._EE.CCVars; // EE - chat stacking
 using Content.Shared.Chat;
 using Content.Shared.Input;
 using Robust.Client.Audio;
 using Robust.Client.AutoGenerated;
-using Robust.Client.GameObjects;
 using Robust.Client.UserInterface;
 using Robust.Client.UserInterface.Controls;
 using Robust.Client.UserInterface.XAML;
 using Robust.Shared.Audio;
+using Robust.Shared.Configuration;
 using Robust.Shared.Input;
 using Robust.Shared.Player;
 using Robust.Shared.Utility;
@@ -21,14 +22,23 @@ public partial class ChatBox : UIWidget
 {
     private readonly ChatUIController _controller;
     private readonly IEntityManager _entManager;
+    [Dependency] private readonly IConfigurationManager _cfg = default!; // EE - Chat stacking
+    [Dependency] private readonly ILocalizationManager _loc = default!; // EE - Chat stacking
 
     public bool Main { get; set; }
 
     public ChatSelectChannel SelectedChannel => ChatInput.ChannelSelector.SelectedChannel;
 
+    // EE - Chat stacking
+    private int _chatStackAmount = 0;
+    private bool ChatStackEnabled => _chatStackAmount > 0;
+    private List<ChatStackData> _chatStackList;
+    // End EE - Chat stacking
+
     public ChatBox()
     {
         RobustXamlLoader.Load(this);
+        IoCManager.InjectDependencies(this);
         _entManager = IoCManager.Resolve<IEntityManager>();
 
         ChatInput.Input.OnTextEntered += OnTextEntered;
@@ -41,6 +51,18 @@ public partial class ChatBox : UIWidget
         _controller.OnAutoHighlightsUpdated += ChatInput.FilterButton.Popup.SetAutoHighlights; // DeltaV - Message highlighting
         _controller.MessageAdded += OnMessageAdded;
         _controller.RegisterChat(this);
+
+        // EE - Chat stacking
+        _chatStackList = new List<ChatStackData>(_chatStackAmount);
+        _cfg.OnValueChanged(EECVars.ChatStackLastLines, UpdateChatStack, true);
+        // End EE - Chat stacking
+    }
+
+    // EE - Chat stacking
+    private void UpdateChatStack(int value)
+    {
+        _chatStackAmount = value >= 0 ? value : 0;
+        Repopulate();
     }
 
     private void OnTextEntered(LineEditEventArgs args)
@@ -63,7 +85,54 @@ public partial class ChatBox : UIWidget
 
         var color = msg.MessageColorOverride ?? msg.Channel.TextColor();
 
-        AddLine(msg.WrappedMessage, color);
+
+        // EE - Chat stacking
+        var index = _chatStackList.FindIndex(data => data.WrappedMessage == msg.WrappedMessage);
+
+        if (index == -1) // this also handles chatstack being disabled, since FindIndex won't find anything in an empty array
+        {
+            TrackNewMessage(msg.WrappedMessage, color);
+            AddLine(msg.WrappedMessage, color);
+            return;
+        }
+
+        UpdateRepeatingLine(index);
+        // End EE - Chat stacking
+    }
+
+    /// <summary>
+    /// Removing and then adding instantly nudges the chat window up before slowly dragging it back down, which makes the whole chat log shake.
+    /// With rapid enough updates, the whole chat becomes unreadable.
+    /// Adding first and then removing does not produce any visual effects.
+    /// The other option is to duplicate OutputPanel functionality and everything internal to the engine it relies on.
+    /// But OutputPanel relies on directly setting Control.Position for control embedding. (which is not exposed to Content.)
+    /// Thanks robustengine, very cool.
+    /// </summary>
+    /// <remarks>
+    /// zero index is the very last line in chat, 1 is the line before the last one, 2 is the line before that, etc.
+    /// </remarks>
+    // EE - Chat stacking
+    private void UpdateRepeatingLine(int index)
+    {
+        _chatStackList[index].RepeatCount++;
+        for (var i = index; i >= 0; i--)
+        {
+            var data = _chatStackList[i];
+            AddLine(data.WrappedMessage, data.ColorOverride, data.RepeatCount);
+            Contents.RemoveEntry(Index.FromEnd(index + 2));
+        }
+    }
+
+    // EE - Chat stacking
+    private void TrackNewMessage(string wrappedMessage, Color colorOverride)
+    {
+        if (!ChatStackEnabled)
+            return;
+
+        if (_chatStackList.Count == _chatStackList.Capacity)
+            _chatStackList.RemoveAt(_chatStackList.Capacity - 1);
+
+        _chatStackList.Insert(0, new ChatStackData(wrappedMessage, colorOverride));
     }
 
     private void OnChannelSelect(ChatSelectChannel channel)
@@ -74,7 +143,7 @@ public partial class ChatBox : UIWidget
     public void Repopulate()
     {
         Contents.Clear();
-
+        _chatStackList = new List<ChatStackData>(_chatStackAmount); // EE - Chat stacking
         foreach (var message in _controller.History)
         {
             OnMessageAdded(message.Item2);
@@ -96,12 +165,25 @@ public partial class ChatBox : UIWidget
         }
     }
 
-    public void AddLine(string message, Color color)
+    public void AddLine(string message, Color color, int repeat = 0) // EE - Chat stacking - repeat
     {
-        var formatted = new FormattedMessage(3);
+        var formatted = new FormattedMessage(4); // EE - Chat stacking - up from 3
         formatted.PushColor(color);
         formatted.AddMarkupOrThrow(message);
         formatted.Pop();
+
+        // EE - Chat stacking
+        if (repeat != 0)
+        {
+            var displayRepeat = repeat + 1;
+            var sizeIncrease = Math.Min(displayRepeat / 6, 5);
+            formatted.AddMarkupOrThrow(_loc.GetString("chat-system-repeated-message-counter",
+                                ("count", displayRepeat),
+                                ("size", 8 + sizeIncrease)
+                                ));
+        }
+        // End EE - Chat stacking
+
         Contents.AddMessage(formatted);
     }
 
@@ -185,5 +267,20 @@ public partial class ChatBox : UIWidget
         ChatInput.Input.OnKeyBindDown -= OnInputKeyBindDown;
         ChatInput.Input.OnTextChanged -= OnTextChanged;
         ChatInput.ChannelSelector.OnChannelSelect -= OnChannelSelect;
+        _cfg.UnsubValueChanged(EECVars.ChatStackLastLines, UpdateChatStack); // EE - Chat stacking
     }
+
+    // EE - Chat stacking
+    private sealed class ChatStackData
+    {
+        public string WrappedMessage;
+        public Color ColorOverride;
+        public int RepeatCount = 0;
+        public ChatStackData(string wrappedMessage, Color colorOverride)
+        {
+            WrappedMessage = wrappedMessage;
+            ColorOverride = colorOverride;
+        }
+    }
+    // End EE - Chat stacking
 }
diff --git a/Content.Shared/_EE/CCVars/CCVars.EE.cs b/Content.Shared/_EE/CCVars/CCVars.EE.cs
new file mode 100644
index 0000000000..151a7270e5
--- /dev/null
+++ b/Content.Shared/_EE/CCVars/CCVars.EE.cs
@@ -0,0 +1,13 @@
+using Robust.Shared.Configuration;
+
+namespace Content.Shared._EE.CCVars;
+
+[CVarDefs]
+public sealed partial class EECVars
+{
+    /// <summary>
+    ///     How many lines back in the chat log to look for collapsing repeated messages into one.
+    /// </summary>
+    public static readonly CVarDef<int> ChatStackLastLines =
+        CVarDef.Create("chat.chatstack_last_lines", 1, CVar.CLIENTONLY | CVar.ARCHIVE, "How far into the chat history to look when looking for similiar messages to coalesce them.");
+}
diff --git a/Resources/Locale/en-US/_EE/chat/chatstack.ftl b/Resources/Locale/en-US/_EE/chat/chatstack.ftl
new file mode 100644
index 0000000000..229a09a9ed
--- /dev/null
+++ b/Resources/Locale/en-US/_EE/chat/chatstack.ftl
@@ -0,0 +1 @@
+chat-system-repeated-message-counter = {" "}[font size={$size}][color=#DD3333][bold]x{$count}![/bold][/color][/font]
\ No newline at end of file
diff --git a/Resources/Locale/en-US/_EE/escape-menu/ui/options-menu.ftl b/Resources/Locale/en-US/_EE/escape-menu/ui/options-menu.ftl
new file mode 100644
index 0000000000..a98b21b90f
--- /dev/null
+++ b/Resources/Locale/en-US/_EE/escape-menu/ui/options-menu.ftl
@@ -0,0 +1,6 @@
+ui-options-chatstack = Automatically merge identical chat messages
+ui-options-chatstack-count = { $count ->
+    [0] Off
+    [1] Last 1 message
+   *[other] Last {$count} messages
+}