diff --git a/source/blender/blenkernel/BKE_DerivedMesh.hh b/source/blender/blenkernel/BKE_DerivedMesh.hh
index ff63a9dd465..43cd3600672 100644
--- a/source/blender/blenkernel/BKE_DerivedMesh.hh
+++ b/source/blender/blenkernel/BKE_DerivedMesh.hh
@@ -58,7 +58,6 @@ struct CCGElem;
 struct CCGKey;
 struct CustomData_MeshMasks;
 struct Depsgraph;
-struct MFace;
 struct Mesh;
 struct ModifierData;
 struct Object;
diff --git a/source/blender/blenkernel/BKE_anim_data.hh b/source/blender/blenkernel/BKE_anim_data.hh
index 19c369958c3..d636ec2e0a4 100644
--- a/source/blender/blenkernel/BKE_anim_data.hh
+++ b/source/blender/blenkernel/BKE_anim_data.hh
@@ -14,7 +14,6 @@
 
 struct AnimData;
 struct BlendDataReader;
-struct BlendLibReader;
 struct BlendWriter;
 struct ID;
 struct Library;
diff --git a/source/blender/blenkernel/BKE_animsys.h b/source/blender/blenkernel/BKE_animsys.h
index 358f3f1b4cd..284f9bb0b23 100644
--- a/source/blender/blenkernel/BKE_animsys.h
+++ b/source/blender/blenkernel/BKE_animsys.h
@@ -18,7 +18,6 @@ extern "C" {
 
 struct AnimData;
 struct BlendDataReader;
-struct BlendLibReader;
 struct BlendWriter;
 struct Depsgraph;
 struct FCurve;
diff --git a/source/blender/blenkernel/BKE_blender.hh b/source/blender/blenkernel/BKE_blender.hh
index 98dfbbb719e..8e442ce6c4b 100644
--- a/source/blender/blenkernel/BKE_blender.hh
+++ b/source/blender/blenkernel/BKE_blender.hh
@@ -12,7 +12,6 @@
 
 struct Main;
 struct UserDef;
-struct bContext;
 
 /**
  * Only to be called on exit Blender.
diff --git a/source/blender/blenkernel/BKE_collection.hh b/source/blender/blenkernel/BKE_collection.hh
index 0dca0a64f8b..510800d1c9f 100644
--- a/source/blender/blenkernel/BKE_collection.hh
+++ b/source/blender/blenkernel/BKE_collection.hh
@@ -20,12 +20,9 @@
 struct BLI_Iterator;
 struct Base;
 struct BlendDataReader;
-struct BlendLibReader;
 struct BlendWriter;
 struct Collection;
-struct Depsgraph;
 struct ID;
-struct Library;
 struct Main;
 struct Object;
 struct Scene;
diff --git a/source/blender/blenkernel/BKE_constraint.h b/source/blender/blenkernel/BKE_constraint.h
index c3ff9a190e1..f6ccb1bd8db 100644
--- a/source/blender/blenkernel/BKE_constraint.h
+++ b/source/blender/blenkernel/BKE_constraint.h
@@ -9,7 +9,6 @@
  */
 
 struct BlendDataReader;
-struct BlendLibReader;
 struct BlendWriter;
 struct Depsgraph;
 struct ID;
diff --git a/source/blender/blenkernel/BKE_curve.hh b/source/blender/blenkernel/BKE_curve.hh
index 49a7b26ed53..9624588b38e 100644
--- a/source/blender/blenkernel/BKE_curve.hh
+++ b/source/blender/blenkernel/BKE_curve.hh
@@ -19,7 +19,6 @@
 struct BezTriple;
 struct BezTriple;
 struct BMEditMesh;
-struct BoundBox;
 struct BPoint;
 struct Curve;
 struct Depsgraph;
diff --git a/source/blender/blenkernel/BKE_data_transfer.h b/source/blender/blenkernel/BKE_data_transfer.h
index f0be0cd5717..b1c8fdf704f 100644
--- a/source/blender/blenkernel/BKE_data_transfer.h
+++ b/source/blender/blenkernel/BKE_data_transfer.h
@@ -17,7 +17,6 @@ extern "C" {
 struct Depsgraph;
 struct Object;
 struct ReportList;
-struct Scene;
 struct SpaceTransform;
 
 /* Warning, those def are stored in files (TransferData modifier), *DO NOT* modify those values. */
diff --git a/source/blender/blenkernel/BKE_fcurve.hh b/source/blender/blenkernel/BKE_fcurve.hh
index 499f7a7e5ee..2ffbb42f5de 100644
--- a/source/blender/blenkernel/BKE_fcurve.hh
+++ b/source/blender/blenkernel/BKE_fcurve.hh
@@ -21,7 +21,6 @@ struct AnimData;
 struct AnimationEvalContext;
 struct BezTriple;
 struct BlendDataReader;
-struct BlendLibReader;
 struct BlendWriter;
 struct LibraryForeachIDData;
 struct PathResolvedRNA;
diff --git a/source/blender/blenkernel/BKE_gpencil_modifier_legacy.h b/source/blender/blenkernel/BKE_gpencil_modifier_legacy.h
index 42799374e7c..98ca3406eb7 100644
--- a/source/blender/blenkernel/BKE_gpencil_modifier_legacy.h
+++ b/source/blender/blenkernel/BKE_gpencil_modifier_legacy.h
@@ -16,7 +16,6 @@ extern "C" {
 
 struct ARegionType;
 struct BlendDataReader;
-struct BlendLibReader;
 struct BlendWriter;
 struct Depsgraph;
 struct GpencilModifierData;
diff --git a/source/blender/blenkernel/BKE_icons.h b/source/blender/blenkernel/BKE_icons.h
index ae786b82f90..d2777da56e2 100644
--- a/source/blender/blenkernel/BKE_icons.h
+++ b/source/blender/blenkernel/BKE_icons.h
@@ -74,8 +74,6 @@ struct Icon_Geom {
 
 typedef struct Icon Icon;
 
-struct BlendDataReader;
-struct BlendWriter;
 struct ID;
 struct ImBuf;
 struct PreviewImage;
diff --git a/source/blender/blenkernel/BKE_idprop.h b/source/blender/blenkernel/BKE_idprop.h
index 59b15f6830a..48edea8f7ed 100644
--- a/source/blender/blenkernel/BKE_idprop.h
+++ b/source/blender/blenkernel/BKE_idprop.h
@@ -16,13 +16,11 @@ extern "C" {
 #endif
 
 struct BlendDataReader;
-struct BlendLibReader;
 struct BlendWriter;
 struct ID;
 struct IDProperty;
 struct IDPropertyUIData;
 struct IDPropertyUIDataEnumItem;
-struct Library;
 
 typedef union IDPropertyTemplate {
   int i;
diff --git a/source/blender/blenkernel/BKE_lattice.hh b/source/blender/blenkernel/BKE_lattice.hh
index c1c84d2d04e..e0fb7511ebc 100644
--- a/source/blender/blenkernel/BKE_lattice.hh
+++ b/source/blender/blenkernel/BKE_lattice.hh
@@ -16,7 +16,6 @@
 #include "BLI_sys_types.h"
 
 struct BMEditMesh;
-struct BoundBox;
 struct BPoint;
 struct Depsgraph;
 struct Lattice;
diff --git a/source/blender/blenkernel/BKE_mesh_remap.hh b/source/blender/blenkernel/BKE_mesh_remap.hh
index 13c877339be..4938c4b2748 100644
--- a/source/blender/blenkernel/BKE_mesh_remap.hh
+++ b/source/blender/blenkernel/BKE_mesh_remap.hh
@@ -15,8 +15,6 @@
 
 #include "BKE_mesh_mapping.hh"
 
-struct CustomData;
-struct CustomData_MeshMasks;
 struct MemArena;
 struct Mesh;
 
diff --git a/source/blender/blenkernel/BKE_nla.h b/source/blender/blenkernel/BKE_nla.h
index 23b71693e4f..aa8295ee0ee 100644
--- a/source/blender/blenkernel/BKE_nla.h
+++ b/source/blender/blenkernel/BKE_nla.h
@@ -28,7 +28,6 @@ struct Speaker;
 struct bAction;
 
 struct BlendDataReader;
-struct BlendLibReader;
 struct BlendWriter;
 struct PointerRNA;
 struct PropertyRNA;
diff --git a/source/blender/blenkernel/BKE_node.hh b/source/blender/blenkernel/BKE_node.hh
index 02af3368ef6..00c543eafc2 100644
--- a/source/blender/blenkernel/BKE_node.hh
+++ b/source/blender/blenkernel/BKE_node.hh
@@ -29,7 +29,6 @@
 #define MAX_SOCKET 512
 
 struct BlendDataReader;
-struct BlendLibReader;
 struct BlendWriter;
 struct FreestyleLineStyle;
 struct GPUMaterial;
diff --git a/source/blender/blenkernel/BKE_node_runtime.hh b/source/blender/blenkernel/BKE_node_runtime.hh
index 6d10cfe8b19..b1b50f9f718 100644
--- a/source/blender/blenkernel/BKE_node_runtime.hh
+++ b/source/blender/blenkernel/BKE_node_runtime.hh
@@ -30,7 +30,6 @@ struct FieldInferencingInterface;
 class NodeDeclaration;
 struct GeometryNodesLazyFunctionGraphInfo;
 namespace anonymous_attribute_lifetime {
-struct RelationsInNode;
 }
 namespace aal = anonymous_attribute_lifetime;
 }  // namespace blender::nodes
diff --git a/source/blender/blenkernel/BKE_object_types.hh b/source/blender/blenkernel/BKE_object_types.hh
index 6642f33b587..759512dbff4 100644
--- a/source/blender/blenkernel/BKE_object_types.hh
+++ b/source/blender/blenkernel/BKE_object_types.hh
@@ -13,7 +13,6 @@
 
 #include "DNA_customdata_types.h" /* #CustomData_MeshMasks. */
 
-struct BoundBox;
 struct bGPdata;
 struct Curve;
 struct CurveCache;
diff --git a/source/blender/blenkernel/BKE_paint.hh b/source/blender/blenkernel/BKE_paint.hh
index 2ace151a537..4d6963e34b6 100644
--- a/source/blender/blenkernel/BKE_paint.hh
+++ b/source/blender/blenkernel/BKE_paint.hh
@@ -26,7 +26,6 @@ struct BMFace;
 struct BMLog;
 struct BMesh;
 struct BlendDataReader;
-struct BlendLibReader;
 struct BlendWriter;
 struct Brush;
 struct CustomDataLayer;
@@ -53,7 +52,6 @@ struct Image;
 struct ImagePool;
 struct ImageUser;
 struct KeyBlock;
-struct ListBase;
 struct Main;
 struct Mesh;
 struct MDeformVert;
diff --git a/source/blender/blenkernel/BKE_shader_fx.h b/source/blender/blenkernel/BKE_shader_fx.h
index ad0eedbba4c..7f393186b51 100644
--- a/source/blender/blenkernel/BKE_shader_fx.h
+++ b/source/blender/blenkernel/BKE_shader_fx.h
@@ -16,7 +16,6 @@ extern "C" {
 
 struct ARegionType;
 struct BlendDataReader;
-struct BlendLibReader;
 struct BlendWriter;
 struct ID;
 struct ListBase;
diff --git a/source/blender/blenkernel/BKE_shrinkwrap.hh b/source/blender/blenkernel/BKE_shrinkwrap.hh
index e68b97dfde0..557f8c6d5da 100644
--- a/source/blender/blenkernel/BKE_shrinkwrap.hh
+++ b/source/blender/blenkernel/BKE_shrinkwrap.hh
@@ -29,7 +29,6 @@
  */
 
 struct BVHTree;
-struct GreasePencilShrinkwrapModifierData;
 struct MDeformVert;
 struct Mesh;
 struct ModifierEvalContext;
diff --git a/source/blender/blenkernel/BKE_subdiv_ccg.hh b/source/blender/blenkernel/BKE_subdiv_ccg.hh
index 7294059d871..dc122853e2e 100644
--- a/source/blender/blenkernel/BKE_subdiv_ccg.hh
+++ b/source/blender/blenkernel/BKE_subdiv_ccg.hh
@@ -19,7 +19,6 @@
 #include "BKE_DerivedMesh.hh"
 
 struct CCGElem;
-struct CCGFace;
 struct CCGKey;
 struct Mesh;
 struct Subdiv;
diff --git a/source/blender/blenkernel/BKE_viewer_path.hh b/source/blender/blenkernel/BKE_viewer_path.hh
index c4dd2fee0ad..fb650f1cf22 100644
--- a/source/blender/blenkernel/BKE_viewer_path.hh
+++ b/source/blender/blenkernel/BKE_viewer_path.hh
@@ -26,9 +26,7 @@
 
 struct BlendWriter;
 struct BlendDataReader;
-struct BlendLibReader;
 struct LibraryForeachIDData;
-struct Library;
 
 namespace blender::bke::id {
 class IDRemapper;
diff --git a/source/blender/blenkernel/intern/CCGSubSurf_intern.h b/source/blender/blenkernel/intern/CCGSubSurf_intern.h
index 6b5b6378f14..acbb65256e6 100644
--- a/source/blender/blenkernel/intern/CCGSubSurf_intern.h
+++ b/source/blender/blenkernel/intern/CCGSubSurf_intern.h
@@ -82,9 +82,6 @@ CCGAllocatorIFC *ccg_getStandardAllocatorIFC(void);
  * Catmull-Clark Gridding Subdivision Surface.
  */
 
-/* TODO(sergey): Get rid of this, it's more or less a bad level call. */
-struct DerivedMesh;
-
 /* ** Data structures, constants. enums ** */
 
 enum {
@@ -256,8 +253,6 @@ void ccgSubSurf__effectedFaceNeighbors(CCGSubSurf *ss,
 
 void ccgSubSurf__sync_legacy(CCGSubSurf *ss);
 
-struct OpenSubdiv_Converter;
-
 /* `CCGSubSurf_util.cc` */
 
 #ifdef DUMP_RESULT_GRIDS