diff --git a/apps/openmw/engine.hpp b/apps/openmw/engine.hpp
index ff362f4b6..1aef62df5 100644
--- a/apps/openmw/engine.hpp
+++ b/apps/openmw/engine.hpp
@@ -33,26 +33,6 @@ namespace Compiler
     class Context;
 }
 
-namespace MWScript
-{
-    class ScriptManager;
-}
-
-namespace MWSound
-{
-    class SoundManager;
-}
-
-namespace MWWorld
-{
-    class World;
-}
-
-namespace MWGui
-{
-    class WindowManager;
-}
-
 namespace Files
 {
     struct ConfigurationManager;
diff --git a/apps/openmw/mwbase/windowmanager.hpp b/apps/openmw/mwbase/windowmanager.hpp
index 29d404777..9bbea9c51 100644
--- a/apps/openmw/mwbase/windowmanager.hpp
+++ b/apps/openmw/mwbase/windowmanager.hpp
@@ -32,7 +32,6 @@ namespace MyGUI
 
 namespace ESM
 {
-    struct Class;
     class ESMReader;
     class ESMWriter;
     struct CellId;
diff --git a/apps/openmw/mwgui/container.hpp b/apps/openmw/mwgui/container.hpp
index feda123fb..85c0dddc6 100644
--- a/apps/openmw/mwgui/container.hpp
+++ b/apps/openmw/mwgui/container.hpp
@@ -6,11 +6,6 @@
 
 #include "itemmodel.hpp"
 
-namespace MWWorld
-{
-    class Environment;
-}
-
 namespace MyGUI
 {
     class Gui;
@@ -19,7 +14,6 @@ namespace MyGUI
 
 namespace MWGui
 {
-    class WindowManager;
     class ContainerWindow;
     class ItemView;
     class SortFilterItemModel;
diff --git a/apps/openmw/mwgui/dialogue.hpp b/apps/openmw/mwgui/dialogue.hpp
index 02401f2e1..ac6303e20 100644
--- a/apps/openmw/mwgui/dialogue.hpp
+++ b/apps/openmw/mwgui/dialogue.hpp
@@ -15,11 +15,6 @@ namespace Gui
     class MWList;
 }
 
-namespace MWGui
-{
-    class WindowManager;
-}
-
 namespace MWGui
 {
     class ResponseCallback;
diff --git a/apps/openmw/mwgui/race.hpp b/apps/openmw/mwgui/race.hpp
index 0299c2a1a..170c1dbce 100644
--- a/apps/openmw/mwgui/race.hpp
+++ b/apps/openmw/mwgui/race.hpp
@@ -7,11 +7,6 @@
 #include <MyGUI_RenderManager.h>
 
 
-namespace MWGui
-{
-    class WindowManager;
-}
-
 namespace MWRender
 {
     class RaceSelectionPreview;
diff --git a/apps/openmw/mwgui/review.hpp b/apps/openmw/mwgui/review.hpp
index bd17c7afb..cb847536d 100644
--- a/apps/openmw/mwgui/review.hpp
+++ b/apps/openmw/mwgui/review.hpp
@@ -11,11 +11,6 @@ namespace ESM
     struct Spell;
 }
 
-namespace MWGui
-{
-    class WindowManager;
-}
-
 namespace MWGui
 {
     class ReviewDialog : public WindowModal
diff --git a/apps/openmw/mwgui/settingswindow.hpp b/apps/openmw/mwgui/settingswindow.hpp
index 6f25dd114..c268514dc 100644
--- a/apps/openmw/mwgui/settingswindow.hpp
+++ b/apps/openmw/mwgui/settingswindow.hpp
@@ -3,11 +3,6 @@
 
 #include "windowbase.hpp"
 
-namespace MWGui
-{
-    class WindowManager;
-}
-
 namespace MWGui
 {
     class SettingsWindow : public WindowBase
diff --git a/apps/openmw/mwgui/spellbuyingwindow.hpp b/apps/openmw/mwgui/spellbuyingwindow.hpp
index 622548c95..f46c43796 100644
--- a/apps/openmw/mwgui/spellbuyingwindow.hpp
+++ b/apps/openmw/mwgui/spellbuyingwindow.hpp
@@ -15,11 +15,6 @@ namespace MyGUI
   class Widget;
 }
 
-namespace MWGui
-{
-    class WindowManager;
-}
-
 namespace MWGui
 {
     class SpellBuyingWindow : public ReferenceInterface, public WindowBase
diff --git a/apps/openmw/mwgui/statswindow.hpp b/apps/openmw/mwgui/statswindow.hpp
index 24f302580..bf78cde34 100644
--- a/apps/openmw/mwgui/statswindow.hpp
+++ b/apps/openmw/mwgui/statswindow.hpp
@@ -6,8 +6,6 @@
 
 namespace MWGui
 {
-    class WindowManager;
-
     class StatsWindow : public WindowPinnableBase, public NoDrop, public StatsListener
     {
         public:
diff --git a/apps/openmw/mwgui/textinput.hpp b/apps/openmw/mwgui/textinput.hpp
index 84d9d032d..4d365eb44 100644
--- a/apps/openmw/mwgui/textinput.hpp
+++ b/apps/openmw/mwgui/textinput.hpp
@@ -3,11 +3,6 @@
 
 #include "windowbase.hpp"
 
-namespace MWGui
-{
-    class WindowManager;
-}
-
 namespace MWGui
 {
     class TextInputDialog : public WindowModal
diff --git a/apps/openmw/mwgui/travelwindow.hpp b/apps/openmw/mwgui/travelwindow.hpp
index 962d17161..00b7db730 100644
--- a/apps/openmw/mwgui/travelwindow.hpp
+++ b/apps/openmw/mwgui/travelwindow.hpp
@@ -11,12 +11,6 @@ namespace MyGUI
   class Widget;
 }
 
-namespace MWGui
-{
-    class WindowManager;
-}
-
-
 namespace MWGui
 {
     class TravelWindow : public ReferenceInterface, public WindowBase
diff --git a/apps/openmw/mwgui/windowbase.hpp b/apps/openmw/mwgui/windowbase.hpp
index 8afb2321e..90ef2118d 100644
--- a/apps/openmw/mwgui/windowbase.hpp
+++ b/apps/openmw/mwgui/windowbase.hpp
@@ -3,11 +3,6 @@
 
 #include "layout.hpp"
 
-namespace MWBase
-{
-    class WindowManager;
-}
-
 namespace MWWorld
 {
     class Ptr;
@@ -15,7 +10,6 @@ namespace MWWorld
 
 namespace MWGui
 {
-    class WindowManager;
     class DragAndDrop;
 
     class WindowBase: public Layout
diff --git a/apps/openmw/mwgui/windowmanagerimp.hpp b/apps/openmw/mwgui/windowmanagerimp.hpp
index cc1a1b694..3fd8b132f 100644
--- a/apps/openmw/mwgui/windowmanagerimp.hpp
+++ b/apps/openmw/mwgui/windowmanagerimp.hpp
@@ -114,7 +114,6 @@ namespace MWGui
   class TrainingWindow;
   class SpellIcons;
   class MerchantRepair;
-  class Repair;
   class SoulgemDialog;
   class Recharge;
   class CompanionWindow;
diff --git a/apps/openmw/mwgui/windowpinnablebase.hpp b/apps/openmw/mwgui/windowpinnablebase.hpp
index a94212819..c91f0a148 100644
--- a/apps/openmw/mwgui/windowpinnablebase.hpp
+++ b/apps/openmw/mwgui/windowpinnablebase.hpp
@@ -5,8 +5,6 @@
 
 namespace MWGui
 {
-    class WindowManager;
-
     class WindowPinnableBase: public WindowBase
     {
     public:
diff --git a/apps/openmw/mwscript/interpretercontext.hpp b/apps/openmw/mwscript/interpretercontext.hpp
index c1481d6d0..298454bcd 100644
--- a/apps/openmw/mwscript/interpretercontext.hpp
+++ b/apps/openmw/mwscript/interpretercontext.hpp
@@ -10,16 +10,6 @@
 
 #include "../mwworld/ptr.hpp"
 
-namespace MWSound
-{
-    class SoundManager;
-}
-
-namespace MWInput
-{
-    struct MWInputManager;
-}
-
 namespace MWScript
 {
     class Locals;
diff --git a/apps/openmw/mwworld/scene.hpp b/apps/openmw/mwworld/scene.hpp
index a70d3ccdd..f87a0ca73 100644
--- a/apps/openmw/mwworld/scene.hpp
+++ b/apps/openmw/mwworld/scene.hpp
@@ -36,7 +36,6 @@ namespace Loading
 namespace DetourNavigator
 {
     struct Navigator;
-    class Water;
 }
 
 namespace MWRender
diff --git a/apps/openmw/mwworld/worldimp.hpp b/apps/openmw/mwworld/worldimp.hpp
index 33b23e065..5447e20c3 100644
--- a/apps/openmw/mwworld/worldimp.hpp
+++ b/apps/openmw/mwworld/worldimp.hpp
@@ -60,8 +60,6 @@ namespace ToUTF8
     class Utf8Encoder;
 }
 
-struct ContentLoader;
-
 namespace MWPhysics
 {
     class Object;
diff --git a/components/nifosg/controller.hpp b/components/nifosg/controller.hpp
index 96beafcbb..b45916693 100644
--- a/components/nifosg/controller.hpp
+++ b/components/nifosg/controller.hpp
@@ -24,11 +24,6 @@ namespace osg
     class Material;
 }
 
-namespace osgParticle
-{
-    class Emitter;
-}
-
 namespace NifOsg
 {