diff --git a/src/actor.h b/src/actor.h
index d6657a83e..2436cdaaa 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -1422,8 +1422,6 @@ public:
 	int ApplyDamageFactor(FName damagetype, int damage) const;
 	int GetModifiedDamage(FName damagetype, int damage, bool passive);
 	void DeleteAttachedLights();
-	static void DeleteAllAttachedLights();
-	static void RecreateAllAttachedLights();
 	bool isFrozen();
 
 	bool				hasmodel;
diff --git a/src/c_cmds.cpp b/src/c_cmds.cpp
index 43f84a0d7..fac4ff6a3 100644
--- a/src/c_cmds.cpp
+++ b/src/c_cmds.cpp
@@ -945,7 +945,8 @@ static void PrintFilteredActorList(const ActorTypeChecker IsActorType, const cha
 			}
 		}
 	}
-	TThinkerIterator<AActor> it;
+	// This only works on the primary level.
+	auto it = currentUILevel->GetThinkerIterator<AActor>();
 
 	while ( (mo = it.Next()) )
 	{
diff --git a/src/d_net.cpp b/src/d_net.cpp
index 33a6a3f3c..bd7504098 100644
--- a/src/d_net.cpp
+++ b/src/d_net.cpp
@@ -2080,12 +2080,12 @@ uint8_t *FDynamicBuffer::GetData (int *len)
 }
 
 
-static int RemoveClass(const PClass *cls)
+static int RemoveClass(FLevelLocals *Level, const PClass *cls)
 {
 	AActor *actor;
 	int removecount = 0;
 	bool player = false;
-	TThinkerIterator<AActor> iterator(cls);
+	auto iterator = Level->GetThinkerIterator<AActor>(cls->TypeName);
 	while ((actor = iterator.Next()))
 	{
 		if (actor->IsA(cls))
@@ -2581,11 +2581,11 @@ void Net_DoCommand (int type, uint8_t **stream, int player)
 		PClassActor *cls = PClass::FindActor(s);
 		if (cls != NULL && cls->IsDescendantOf(RUNTIME_CLASS(AActor)))
 		{
-			removecount = RemoveClass(cls);
+			removecount = RemoveClass(&level, cls);
 			const PClass *cls_rep = cls->GetReplacement();
 			if (cls != cls_rep)
 			{
-				removecount += RemoveClass(cls_rep);
+				removecount += RemoveClass(&leve, cls_rep);
 			}
 			Printf("Removed %d actors of type %s.\n", removecount, s);
 		}
diff --git a/src/g_levellocals.h b/src/g_levellocals.h
index a8d1486dc..d4e236b64 100644
--- a/src/g_levellocals.h
+++ b/src/g_levellocals.h
@@ -232,6 +232,9 @@ public:
 	void SecretExitLevel(int position);
 	void DoLoadLevel(const FString &nextmapname, int position, bool autosave, bool newGame);
 
+	void DeleteAllAttachedLights();
+	void RecreateAllAttachedLights();
+
 
 private:
 	// Work data for CollectConnectedGroups.
diff --git a/src/g_shared/a_decals.cpp b/src/g_shared/a_decals.cpp
index 5546aef08..a0a27aacd 100644
--- a/src/g_shared/a_decals.cpp
+++ b/src/g_shared/a_decals.cpp
@@ -54,8 +54,6 @@ struct SpreadInfo
 	TArray<side_t *> SpreadStack;
 };
 
-static int ImpactCount;
-
 CVAR (Bool, cl_spreaddecals, true, CVAR_ARCHIVE)
 
 IMPLEMENT_CLASS(DBaseDecal, false, true)
@@ -652,18 +650,16 @@ DBaseDecal *DImpactDecal::CloneSelf (const FDecalTemplate *tpl, double ix, doubl
 
 CCMD (countdecals)
 {
-	Printf ("%d impact decals\n", ImpactCount);
-}
+	for (auto Level : AllLevels())
+	{
+		auto iterator = Level->GetThinkerIterator<DImpactDecal>(NAME_None, STAT_AUTODECAL);
+		int count = 0;
 
-CCMD (countdecalsreal)
-{
-	TThinkerIterator<DImpactDecal> iterator (STAT_AUTODECAL);
-	int count = 0;
+		while (iterator.Next())
+			count++;
 
-	while (iterator.Next())
-		count++;
-
-	Printf ("Counted %d impact decals\n", count);
+		Printf("%s: Counted %d impact decals\n", Level->MapName.GetChars(), count);
+	}
 }
 
 CCMD (spray)
diff --git a/src/g_shared/a_dynlight.cpp b/src/g_shared/a_dynlight.cpp
index a24a82bfe..92720cddc 100644
--- a/src/g_shared/a_dynlight.cpp
+++ b/src/g_shared/a_dynlight.cpp
@@ -71,8 +71,11 @@ static FRandom randLight;
 
 CUSTOM_CVAR (Bool, gl_lights, true, CVAR_ARCHIVE | CVAR_GLOBALCONFIG | CVAR_NOINITCALL)
 {
-	if (self) AActor::RecreateAllAttachedLights();
-	else AActor::DeleteAllAttachedLights();
+	for (auto Level : AllLevels())
+	{
+		if (self) Level->RecreateAllAttachedLights();
+		else Level->DeleteAllAttachedLights();
+	}
 }
 
 CVAR (Bool, gl_attachedlights, true, CVAR_ARCHIVE | CVAR_GLOBALCONFIG);
@@ -833,9 +836,9 @@ void AActor::DeleteAttachedLights()
 //
 //==========================================================================
 
-void AActor::DeleteAllAttachedLights()
+void FLevelLocals::DeleteAllAttachedLights()
 {
-	TThinkerIterator<AActor> it;
+	auto it = GetThinkerIterator<AActor>();
 	AActor * a;
 
 	while ((a=it.Next())) 
@@ -850,9 +853,9 @@ void AActor::DeleteAllAttachedLights()
 //
 //==========================================================================
 
-void AActor::RecreateAllAttachedLights()
+void FLevelLocals::RecreateAllAttachedLights()
 {
-	TThinkerIterator<AActor> it;
+	auto it = GetThinkerIterator<AActor>();
 	AActor * a;
 
 	while ((a=it.Next())) 
diff --git a/src/gl/renderer/gl_renderer.cpp b/src/gl/renderer/gl_renderer.cpp
index 00a4f3460..38a0ad604 100644
--- a/src/gl/renderer/gl_renderer.cpp
+++ b/src/gl/renderer/gl_renderer.cpp
@@ -116,7 +116,6 @@ void FGLRenderer::Initialize(int width, int height)
 FGLRenderer::~FGLRenderer() 
 {
 	FlushModels();
-	AActor::DeleteAllAttachedLights();
 	TexMan.FlushAll();
 	if (mShaderManager != nullptr) delete mShaderManager;
 	if (mSamplerManager != nullptr) delete mSamplerManager;
diff --git a/src/p_acs.cpp b/src/p_acs.cpp
index a51343c7f..23d685677 100644
--- a/src/p_acs.cpp
+++ b/src/p_acs.cpp
@@ -2213,6 +2213,7 @@ bool FBehavior::Init(FLevelLocals *Level, int lumpnum, FileReader * fr, int len)
 	uint8_t *object;
 	int i;
 
+	this->Level = Level;
 	LumpNum = lumpnum;
 
 	// Now that everything is set up, record this module as being among the loaded modules.
@@ -3270,7 +3271,7 @@ void FBehavior::StartTypedScripts (uint16_t type, AActor *activator, bool always
 		ptr = &Scripts[i];
 		if (ptr->Type == type)
 		{
-			DLevelScript *runningScript = P_GetScriptGoing (&level, activator, NULL, ptr->Number,
+			DLevelScript *runningScript = P_GetScriptGoing (Level, activator, NULL, ptr->Number,
 				ptr, this, &arg1, 1, always ? ACS_ALWAYS : 0);
 			if (nullptr != runningScript && runNow)
 			{
diff --git a/src/p_acs.h b/src/p_acs.h
index 7eea0c22a..6fae24de9 100644
--- a/src/p_acs.h
+++ b/src/p_acs.h
@@ -387,6 +387,7 @@ private:
 
 	ACSFormat Format;
 
+	FLevelLocals *Level;
 	int LumpNum;
 	uint8_t *Data;
 	int DataSize;
diff --git a/src/p_effect.cpp b/src/p_effect.cpp
index a621d1961..20312ced3 100644
--- a/src/p_effect.cpp
+++ b/src/p_effect.cpp
@@ -329,7 +329,7 @@ void P_RunEffects (FLevelLocals *Level)
 	int	pnum = players[consoleplayer].camera->Sector->Index() * Level->sectors.Size();
 
 	AActor *actor;
-	TThinkerIterator<AActor> iterator;
+	auto iterator = Level->GetThinkerIterator<AActor>();
 
 	while ( (actor = iterator.Next ()) )
 	{