diff --git a/.editorconfig b/.editorconfig
index 7b3f63dc7c..8d57dda4ac 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -634,6 +634,9 @@ dotnet_diagnostic.CA1047.severity = warning
 # Declare types in namespaces.
 dotnet_diagnostic.CA1050.severity = warning
 
+# Static holder types should be 'Static' or 'NotInheritable'.
+dotnet_diagnostic.CA1052.severity = warning
+
 # Do not hide base class methods.
 dotnet_diagnostic.CA1061.severity = warning
 
diff --git a/OpenRA.Game/Map/TerrainInfo.cs b/OpenRA.Game/Map/TerrainInfo.cs
index e1ccc343b6..24b3d12fd0 100644
--- a/OpenRA.Game/Map/TerrainInfo.cs
+++ b/OpenRA.Game/Map/TerrainInfo.cs
@@ -69,7 +69,7 @@ namespace OpenRA
 
 	// HACK: Temporary placeholder to avoid having to change all the traits that reference this constant.
 	// This can be removed after the palette references have been moved from traits to sequences.
-	public class TileSet
+	public static class TileSet
 	{
 		public const string TerrainPaletteInternalName = "terrain";
 	}
diff --git a/OpenRA.Game/Network/GeoIP.cs b/OpenRA.Game/Network/GeoIP.cs
index 834dd8f644..fee2056058 100644
--- a/OpenRA.Game/Network/GeoIP.cs
+++ b/OpenRA.Game/Network/GeoIP.cs
@@ -19,7 +19,7 @@ using ICSharpCode.SharpZipLib.Zip;
 
 namespace OpenRA.Network
 {
-	public class GeoIP
+	public static class GeoIP
 	{
 		sealed class IP2LocationReader
 		{
diff --git a/OpenRA.Game/Network/Nat.cs b/OpenRA.Game/Network/Nat.cs
index 8d008a74a6..b26d54051f 100644
--- a/OpenRA.Game/Network/Nat.cs
+++ b/OpenRA.Game/Network/Nat.cs
@@ -17,7 +17,7 @@ namespace OpenRA.Network
 {
 	public enum NatStatus { Enabled, Disabled, NotSupported }
 
-	public class Nat
+	public static class Nat
 	{
 		public static NatStatus Status => NatUtility.IsSearching ? natDevice != null ? NatStatus.Enabled : NatStatus.NotSupported : NatStatus.Disabled;
 
diff --git a/OpenRA.Game/Support/HttpClientFactory.cs b/OpenRA.Game/Support/HttpClientFactory.cs
index d947d7ad34..7450e9d3aa 100644
--- a/OpenRA.Game/Support/HttpClientFactory.cs
+++ b/OpenRA.Game/Support/HttpClientFactory.cs
@@ -14,7 +14,7 @@ using System.Net.Http;
 
 namespace OpenRA.Support
 {
-	public class HttpClientFactory
+	public static class HttpClientFactory
 	{
 #if NET5_0_OR_GREATER
 		const int MaxConnectionPerServer = 20;
diff --git a/OpenRA.Mods.Common/FileFormats/ImaAdpcmReader.cs b/OpenRA.Mods.Common/FileFormats/ImaAdpcmReader.cs
index 018103a40d..795c77fd3c 100644
--- a/OpenRA.Mods.Common/FileFormats/ImaAdpcmReader.cs
+++ b/OpenRA.Mods.Common/FileFormats/ImaAdpcmReader.cs
@@ -13,7 +13,7 @@ using System.IO;
 
 namespace OpenRA.Mods.Common.FileFormats
 {
-	public class ImaAdpcmReader
+	public static class ImaAdpcmReader
 	{
 		static readonly int[] IndexAdjust = { -1, -1, -1, -1, 2, 4, 6, 8 };
 		static readonly int[] StepTable =
diff --git a/OpenRA.Mods.Common/FileFormats/WestwoodCompressedReader.cs b/OpenRA.Mods.Common/FileFormats/WestwoodCompressedReader.cs
index 6cd73ec394..97b509ced5 100644
--- a/OpenRA.Mods.Common/FileFormats/WestwoodCompressedReader.cs
+++ b/OpenRA.Mods.Common/FileFormats/WestwoodCompressedReader.cs
@@ -15,7 +15,7 @@ using System;
 
 namespace OpenRA.Mods.Common.FileFormats
 {
-	public class WestwoodCompressedReader
+	public static class WestwoodCompressedReader
 	{
 		static readonly int[] AudWsStepTable2 = { -2, -1, 0, 1 };
 		static readonly int[] AudWsStepTable4 = { -9, -8, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 8 };
diff --git a/OpenRA.Mods.Common/Installer/InstallerUtils.cs b/OpenRA.Mods.Common/Installer/InstallerUtils.cs
index 0f0f71a42e..726da2ac01 100644
--- a/OpenRA.Mods.Common/Installer/InstallerUtils.cs
+++ b/OpenRA.Mods.Common/Installer/InstallerUtils.cs
@@ -16,7 +16,7 @@ using FS = OpenRA.FileSystem.FileSystem;
 
 namespace OpenRA.Mods.Common.Installer
 {
-	public class InstallerUtils
+	public static class InstallerUtils
 	{
 		public static bool IsValidSourcePath(string path, ModContent.ModSource source)
 		{
diff --git a/OpenRA.Mods.Common/Lint/LintExts.cs b/OpenRA.Mods.Common/Lint/LintExts.cs
index de50114419..5803dad879 100644
--- a/OpenRA.Mods.Common/Lint/LintExts.cs
+++ b/OpenRA.Mods.Common/Lint/LintExts.cs
@@ -19,7 +19,7 @@ using OpenRA.Traits;
 
 namespace OpenRA.Mods.Common.Lint
 {
-	public class LintExts
+	public static class LintExts
 	{
 		public static IEnumerable<string> GetFieldValues(object ruleInfo, FieldInfo fieldInfo,
 			LintDictionaryReference dictionaryReference = LintDictionaryReference.None)
diff --git a/OpenRA.Mods.Common/Traits/Encyclopedia.cs b/OpenRA.Mods.Common/Traits/Encyclopedia.cs
index e978764c42..232b6ad312 100644
--- a/OpenRA.Mods.Common/Traits/Encyclopedia.cs
+++ b/OpenRA.Mods.Common/Traits/Encyclopedia.cs
@@ -27,9 +27,8 @@ namespace OpenRA.Mods.Common.Traits
 		public override object Create(ActorInitializer init) { return Encyclopedia.Instance; }
 	}
 
-	public class Encyclopedia
+	public readonly struct Encyclopedia
 	{
-		public static readonly Encyclopedia Instance = new();
-		Encyclopedia() { }
+		public static readonly object Instance = default(Encyclopedia);
 	}
 }
diff --git a/OpenRA.Mods.Common/Traits/Render/RenderUtils.cs b/OpenRA.Mods.Common/Traits/Render/RenderUtils.cs
index a59078e790..59a46a67f7 100644
--- a/OpenRA.Mods.Common/Traits/Render/RenderUtils.cs
+++ b/OpenRA.Mods.Common/Traits/Render/RenderUtils.cs
@@ -11,7 +11,7 @@
 
 namespace OpenRA.Mods.Common.Traits.Render
 {
-	public class RenderUtils
+	public static class RenderUtils
 	{
 		public static int ZOffsetFromCenter(Actor self, WPos pos, int offset)
 		{
diff --git a/OpenRA.Mods.Common/Widgets/Logic/Ingame/OrderButtonsChromeLogic.cs b/OpenRA.Mods.Common/Widgets/Logic/Ingame/OrderButtonsChromeLogic.cs
index 797d46e7d3..4f57c7f502 100644
--- a/OpenRA.Mods.Common/Widgets/Logic/Ingame/OrderButtonsChromeLogic.cs
+++ b/OpenRA.Mods.Common/Widgets/Logic/Ingame/OrderButtonsChromeLogic.cs
@@ -55,7 +55,7 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 		}
 	}
 
-	public class OrderButtonsChromeUtils
+	public static class OrderButtonsChromeUtils
 	{
 		public static void BindOrderButton<T>(World world, ButtonWidget w, string icon)
 			where T : IOrderGenerator, new()