diff --git a/doc/source/api/gdal_fwd.rst b/doc/source/api/gdal_fwd.rst
new file mode 100644
index 000000000000..8a5936b93422
--- /dev/null
+++ b/doc/source/api/gdal_fwd.rst
@@ -0,0 +1,18 @@
+..
+   The documentation displayed on this page is automatically generated from
+   Doxygen comments using the Breathe extension. Edits to the documentation
+   can be made by making changes in the appropriate .cpp files.
+
+.. _gdal_fwd:
+
+================================================================================
+gdal_fwd.h: Forward definitions of GDAL/OGR/OSR C handle types.
+================================================================================
+
+gdal_fwd.h
+----------
+
+.. versionadded:: 3.11
+
+.. doxygenfile:: gdal_fwd.h
+   :project: api
diff --git a/doc/source/api/index.rst b/doc/source/api/index.rst
index 652fdd2e39df..8cad65630f72 100644
--- a/doc/source/api/index.rst
+++ b/doc/source/api/index.rst
@@ -16,6 +16,7 @@ API
        :maxdepth: 1
 
        cpl
+       gdal_fwd
        raster_c_api
        vector_c_api
        gdal_alg
diff --git a/gcore/CMakeLists.txt b/gcore/CMakeLists.txt
index 044a4c667196..325e34d1049a 100644
--- a/gcore/CMakeLists.txt
+++ b/gcore/CMakeLists.txt
@@ -213,6 +213,7 @@ target_public_header(
   HEADERS
   ${CMAKE_CURRENT_BINARY_DIR}/gdal_version_full/gdal_version.h
   gdal.h
+  gdal_fwd.h
   gdalalgorithm.h
   gdaljp2metadata.h
   gdaljp2abstractdataset.h
diff --git a/gcore/gdal.h b/gcore/gdal.h
index 8a8f414a826d..8f83b5d3bc9b 100644
--- a/gcore/gdal.h
+++ b/gcore/gdal.h
@@ -24,6 +24,7 @@
 #if defined(GDAL_COMPILATION)
 #define DO_NOT_DEFINE_GDAL_DATE_NAME
 #endif
+#include "gdal_fwd.h"
 #include "gdal_version.h"
 #include "cpl_port.h"
 #include "cpl_error.h"
@@ -365,36 +366,9 @@ const char CPL_DLL *GDALGetPaletteInterpretationName(GDALPaletteInterp);
 #endif
 
 /* -------------------------------------------------------------------- */
-/*      Define handle types related to various internal classes.        */
+/*      Types, enumerations.                                            */
 /* -------------------------------------------------------------------- */
 
-/** Opaque type used for the C bindings of the C++ GDALMajorObject class */
-typedef void *GDALMajorObjectH;
-
-/** Opaque type used for the C bindings of the C++ GDALDataset class */
-typedef void *GDALDatasetH;
-
-/** Opaque type used for the C bindings of the C++ GDALRasterBand class */
-typedef void *GDALRasterBandH;
-
-/** Opaque type used for the C bindings of the C++ GDALDriver class */
-typedef void *GDALDriverH;
-
-/** Opaque type used for the C bindings of the C++ GDALColorTable class */
-typedef void *GDALColorTableH;
-
-/** Opaque type used for the C bindings of the C++ GDALRasterAttributeTable
- * class */
-typedef void *GDALRasterAttributeTableH;
-
-/** Opaque type used for the C bindings of the C++ GDALAsyncReader class */
-typedef void *GDALAsyncReaderH;
-
-/** Opaque type used for the C bindings of the C++ GDALRelationship class
- *  @since GDAL 3.6
- */
-typedef void *GDALRelationshipH;
-
 /** Type to express pixel, line or band spacing. Signed 64 bit integer. */
 typedef GIntBig GSpacing;
 
@@ -422,19 +396,6 @@ typedef enum
     GEDTST_JSON
 } GDALExtendedDataTypeSubType;
 
-/** Opaque type for C++ GDALExtendedDataType */
-typedef struct GDALExtendedDataTypeHS *GDALExtendedDataTypeH;
-/** Opaque type for C++ GDALEDTComponent */
-typedef struct GDALEDTComponentHS *GDALEDTComponentH;
-/** Opaque type for C++ GDALGroup */
-typedef struct GDALGroupHS *GDALGroupH;
-/** Opaque type for C++ GDALMDArray */
-typedef struct GDALMDArrayHS *GDALMDArrayH;
-/** Opaque type for C++ GDALAttribute */
-typedef struct GDALAttributeHS *GDALAttributeH;
-/** Opaque type for C++ GDALDimension */
-typedef struct GDALDimensionHS *GDALDimensionH;
-
 /* ==================================================================== */
 /*      Registration/driver related.                                    */
 /* ==================================================================== */
@@ -1435,12 +1396,6 @@ bool CPL_DLL GDALDatasetSetQueryLoggerFunc(
 /*      Informational utilities about subdatasets in file names         */
 /* ==================================================================== */
 
-/**
- *  Opaque type used for the C bindings of the C++ GDALSubdatasetInfo class
- *  @since GDAL 3.8
-*/
-typedef struct GDALSubdatasetInfo *GDALSubdatasetInfoH;
-
 /**
  * @brief Returns a new GDALSubdatasetInfo object with methods to extract
  *        and manipulate subdataset information.
diff --git a/gcore/gdal_fwd.h b/gcore/gdal_fwd.h
new file mode 100644
index 000000000000..59cc144259b0
--- /dev/null
+++ b/gcore/gdal_fwd.h
@@ -0,0 +1,205 @@
+/******************************************************************************
+ *
+ * Project:  GDAL
+ * Purpose:  Forward definitions of GDAL/OGR/OSR C handle types.
+ * Author:   Even Rouault <even dot rouault at spatialys.com>
+ *
+ ******************************************************************************
+ * Copyright (c) 1998, 2002 Frank Warmerdam
+ * Copyright (c) 2007-2024, Even Rouault <even dot rouault at spatialys.com>
+ *
+ * SPDX-License-Identifier: MIT
+ ****************************************************************************/
+
+#ifndef GDAL_FWD_H_INCLUDED
+#define GDAL_FWD_H_INCLUDED
+
+/**
+ * \file gdal_fwd.h
+ *
+ * Forward definitions of GDAL/OGR/OSR C handle types.
+ *
+ * Users should only rely on the type name, and not its definition, which
+ * could change in later versions.
+ *
+ * @since GDAL 3.11
+ */
+
+/*!
+\section gdal_fwd_raster Raster related types.
+*/
+
+/** Opaque type used for the C bindings of the C++ GDALMajorObject class */
+typedef void *GDALMajorObjectH;
+
+/** Opaque type used for the C bindings of the C++ GDALDataset class */
+typedef void *GDALDatasetH;
+
+/** Opaque type used for the C bindings of the C++ GDALRasterBand class */
+typedef void *GDALRasterBandH;
+
+/** Opaque type used for the C bindings of the C++ GDALDriver class */
+typedef void *GDALDriverH;
+
+/** Opaque type used for the C bindings of the C++ GDALColorTable class */
+typedef void *GDALColorTableH;
+
+/** Opaque type used for the C bindings of the C++ GDALRasterAttributeTable
+ * class */
+typedef void *GDALRasterAttributeTableH;
+
+/** Opaque type used for the C bindings of the C++ GDALAsyncReader class */
+typedef void *GDALAsyncReaderH;
+
+/** Opaque type used for the C bindings of the C++ GDALRelationship class
+ *  @since GDAL 3.6
+ */
+typedef void *GDALRelationshipH;
+
+/** Opaque type for C++ GDALExtendedDataType */
+typedef struct GDALExtendedDataTypeHS *GDALExtendedDataTypeH;
+/** Opaque type for C++ GDALEDTComponent */
+typedef struct GDALEDTComponentHS *GDALEDTComponentH;
+/** Opaque type for C++ GDALGroup */
+typedef struct GDALGroupHS *GDALGroupH;
+/** Opaque type for C++ GDALMDArray */
+typedef struct GDALMDArrayHS *GDALMDArrayH;
+/** Opaque type for C++ GDALAttribute */
+typedef struct GDALAttributeHS *GDALAttributeH;
+/** Opaque type for C++ GDALDimension */
+typedef struct GDALDimensionHS *GDALDimensionH;
+
+/**
+ *  Opaque type used for the C bindings of the C++ GDALSubdatasetInfo class
+ *  @since GDAL 3.8
+*/
+typedef struct GDALSubdatasetInfo *GDALSubdatasetInfoH;
+
+/*!
+\section gdal_fwd_geometry Geometry related types.
+*/
+
+#if defined(GDAL_DEBUG)
+/** Opaque type for a geometry */
+typedef struct OGRGeometryHS *OGRGeometryH;
+#else
+/** Opaque type for a geometry */
+typedef void *OGRGeometryH;
+#endif
+
+/** Opaque type for a geometry transformer. */
+typedef struct OGRGeomTransformer *OGRGeomTransformerH;
+
+/** Opaque type for OGRGeomCoordinatePrecision */
+typedef struct OGRGeomCoordinatePrecision *OGRGeomCoordinatePrecisionH;
+
+/** Opaque type for WKB export options */
+typedef struct OGRwkbExportOptions OGRwkbExportOptions;
+
+/** Opaque type for a prepared geometry */
+typedef struct _OGRPreparedGeometry *OGRPreparedGeometryH;
+
+/*!
+\section gdal_fwd_field Attribute field, geometry field and layer definitions.
+*/
+
+#if defined(GDAL_DEBUG)
+/** Opaque type for a field definition (OGRFieldDefn) */
+typedef struct OGRFieldDefnHS *OGRFieldDefnH;
+/** Opaque type for a feature definition (OGRFeatureDefn) */
+typedef struct OGRFeatureDefnHS *OGRFeatureDefnH;
+#else
+/** Opaque type for a field definition (OGRFieldDefn) */
+typedef void *OGRFieldDefnH;
+/** Opaque type for a feature definition (OGRFeatureDefn) */
+typedef void *OGRFeatureDefnH;
+#endif
+
+/** Opaque type for a geometry field definition (OGRGeomFieldDefn) */
+typedef struct OGRGeomFieldDefnHS *OGRGeomFieldDefnH;
+
+/** Opaque type for a field domain definition (OGRFieldDomain) */
+typedef struct OGRFieldDomainHS *OGRFieldDomainH;
+
+/*!
+\section gdal_fwd_feature Vector feature type.
+*/
+#if defined(GDAL_DEBUG)
+/** Opaque type for a feature (OGRFeature) */
+typedef struct OGRFeatureHS *OGRFeatureH;
+#else
+/** Opaque type for a feature (OGRFeature) */
+typedef void *OGRFeatureH;
+#endif
+
+/*!
+\section gdal_fwd_layer Vector layer related types.
+*/
+
+#if defined(GDAL_DEBUG)
+/** Opaque type for a layer (OGRLayer) */
+typedef struct OGRLayerHS *OGRLayerH;
+/** Opaque type for a OGR datasource (OGRDataSource) (deprecated) */
+typedef struct OGRDataSourceHS *OGRDataSourceH;
+/** Opaque type for a OGR driver (OGRSFDriver) (deprecated) */
+typedef struct OGRDriverHS *OGRSFDriverH;
+#else
+/** Opaque type for a layer (OGRLayer) */
+typedef void *OGRLayerH;
+/** Opaque type for a OGR datasource (OGRDataSource) (deprecated) */
+typedef void *OGRDataSourceH;
+/** Opaque type for a OGR driver (OGRSFDriver) (deprecated) */
+typedef void *OGRSFDriverH;
+#endif
+
+/*!
+\section gdal_fwd_style Vector styling related types.
+*/
+
+#if defined(GDAL_DEBUG)
+/** Style manager opaque type */
+typedef struct OGRStyleMgrHS *OGRStyleMgrH;
+/** Opaque type for a style table (OGRStyleTable) */
+typedef struct OGRStyleTableHS *OGRStyleTableH;
+/** Style tool opaque type */
+typedef struct OGRStyleToolHS *OGRStyleToolH;
+#else
+/** Style manager opaque type */
+typedef void *OGRStyleMgrH;
+/** Style tool opaque type */
+typedef void *OGRStyleToolH;
+/** Opaque type for a style table (OGRStyleTable) */
+typedef void *OGRStyleTableH;
+#endif
+
+/*!
+\section gdal_fwd_crs CRS and coordinate transformation related types.
+*/
+
+#if defined(GDAL_DEBUG)
+/** Opaque type for a spatial reference system */
+typedef struct OGRSpatialReferenceHS *OGRSpatialReferenceH;
+/** Opaque type for a coordinate transformation object */
+typedef struct OGRCoordinateTransformationHS *OGRCoordinateTransformationH;
+#else
+/** Opaque type for a spatial reference system */
+typedef void *OGRSpatialReferenceH;
+/** Opaque type for a coordinate transformation object */
+typedef void *OGRCoordinateTransformationH;
+#endif
+
+/** Coordinate transformation options. */
+typedef struct OGRCoordinateTransformationOptions
+    *OGRCoordinateTransformationOptionsH;
+
+/*!
+\section gdal_fwd_gnm GNM (Geography Network Models) related types.
+*/
+
+/** Opaque type for a GNMNetwork */
+typedef void *GNMNetworkH;
+
+/** Opaque type for a GNMGenericNetwork */
+typedef void *GNMGenericNetworkH;
+
+#endif  // GDAL_FWD_H_INCLUDED
diff --git a/gnm/gnm_api.h b/gnm/gnm_api.h
index ef6955cc1603..65d2ec731416 100644
--- a/gnm/gnm_api.h
+++ b/gnm/gnm_api.h
@@ -33,10 +33,9 @@
 
 #include "gnm.h"
 
-CPL_C_START
+#include "gdal_fwd.h"
 
-typedef void *GNMNetworkH;
-typedef void *GNMGenericNetworkH;
+CPL_C_START
 
 const char CPL_DLL *CPL_STDCALL GNMGetName(GNMNetworkH hNet);
 
diff --git a/ogr/ogr_api.h b/ogr/ogr_api.h
index f2ddd1764315..94d1f2c6825d 100644
--- a/ogr/ogr_api.h
+++ b/ogr/ogr_api.h
@@ -26,6 +26,7 @@
 #include "cpl_progress.h"
 #include "cpl_minixml.h"
 #include "ogr_core.h"
+#include "gdal_fwd.h"
 
 #include <stdbool.h>
 #include <stddef.h>
@@ -38,36 +39,6 @@ bool CPL_DLL OGRGetGEOSVersion(int *pnMajor, int *pnMinor, int *pnPatch);
 /* -------------------------------------------------------------------- */
 /*      Geometry related functions (ogr_geometry.h)                     */
 /* -------------------------------------------------------------------- */
-#ifndef DEFINEH_OGRGeometryH
-/*! @cond Doxygen_Suppress */
-#define DEFINEH_OGRGeometryH
-/*! @endcond */
-#if defined(DEBUG) || defined(GDAL_DEBUG)
-typedef struct OGRGeometryHS *OGRGeometryH;
-#else
-/** Opaque type for a geometry */
-typedef void *OGRGeometryH;
-#endif
-#endif /* DEFINEH_OGRGeometryH */
-
-#ifndef DEFINED_OGRSpatialReferenceH
-/*! @cond Doxygen_Suppress */
-#define DEFINED_OGRSpatialReferenceH
-/*! @endcond */
-
-#ifndef DOXYGEN_XML
-#if defined(DEBUG) || defined(GDAL_DEBUG)
-typedef struct OGRSpatialReferenceHS *OGRSpatialReferenceH;
-typedef struct OGRCoordinateTransformationHS *OGRCoordinateTransformationH;
-#else
-/** Opaque type for a spatial reference system */
-typedef void *OGRSpatialReferenceH;
-/** Opaque type for a coordinate transformation object */
-typedef void *OGRCoordinateTransformationH;
-#endif
-#endif
-
-#endif /* DEFINED_OGRSpatialReferenceH */
 
 struct _CPLXMLNode;
 
@@ -76,9 +47,6 @@ struct _CPLXMLNode;
 /** Value for a unknown coordinate precision. */
 #define OGR_GEOM_COORD_PRECISION_UNKNOWN 0
 
-/** Opaque type for OGRGeomCoordinatePrecision */
-typedef struct OGRGeomCoordinatePrecision *OGRGeomCoordinatePrecisionH;
-
 OGRGeomCoordinatePrecisionH CPL_DLL OGRGeomCoordinatePrecisionCreate(void);
 void CPL_DLL OGRGeomCoordinatePrecisionDestroy(OGRGeomCoordinatePrecisionH);
 double CPL_DLL
@@ -154,9 +122,6 @@ OGRErr CPL_DLL OGR_G_ExportToWkb(OGRGeometryH, OGRwkbByteOrder,
 OGRErr CPL_DLL OGR_G_ExportToIsoWkb(OGRGeometryH, OGRwkbByteOrder,
                                     unsigned char *);
 
-/** Opaque type for WKB export options */
-typedef struct OGRwkbExportOptions OGRwkbExportOptions;
-
 OGRwkbExportOptions CPL_DLL *OGRwkbExportOptionsCreate(void);
 void CPL_DLL OGRwkbExportOptionsDestroy(OGRwkbExportOptions *);
 void CPL_DLL OGRwkbExportOptionsSetByteOrder(OGRwkbExportOptions *,
@@ -208,8 +173,6 @@ OGRSpatialReferenceH CPL_DLL OGR_G_GetSpatialReference(OGRGeometryH);
 OGRErr CPL_DLL OGR_G_Transform(OGRGeometryH, OGRCoordinateTransformationH);
 OGRErr CPL_DLL OGR_G_TransformTo(OGRGeometryH, OGRSpatialReferenceH);
 
-/** Opaque type for a geometry transformer. */
-typedef struct OGRGeomTransformer *OGRGeomTransformerH;
 OGRGeomTransformerH CPL_DLL
 OGR_GeomTransformer_Create(OGRCoordinateTransformationH,
                            CSLConstList papszOptions) CPL_WARN_UNUSED_RESULT;
@@ -376,9 +339,6 @@ int CPL_DLL OGRGetGenerate_DB2_V72_BYTE_ORDER(void);
 void CPL_DLL OGRSetNonLinearGeometriesEnabledFlag(int bFlag);
 int CPL_DLL OGRGetNonLinearGeometriesEnabledFlag(void);
 
-/** Opaque type for a prepared geometry */
-typedef struct _OGRPreparedGeometry *OGRPreparedGeometryH;
-
 int CPL_DLL OGRHasPreparedGeometrySupport(void);
 OGRPreparedGeometryH CPL_DLL OGRCreatePreparedGeometry(OGRGeometryH hGeom);
 void CPL_DLL OGRDestroyPreparedGeometry(OGRPreparedGeometryH hPreparedGeom);
@@ -391,32 +351,6 @@ int CPL_DLL OGRPreparedGeometryContains(OGRPreparedGeometryH hPreparedGeom,
 /*      Feature related (ogr_feature.h)                                 */
 /* -------------------------------------------------------------------- */
 
-#ifndef DEFINE_OGRFeatureH
-/*! @cond Doxygen_Suppress */
-#define DEFINE_OGRFeatureH
-/*! @endcond */
-#if defined(DEBUG) || defined(GDAL_DEBUG)
-typedef struct OGRFieldDefnHS *OGRFieldDefnH;
-typedef struct OGRFeatureDefnHS *OGRFeatureDefnH;
-typedef struct OGRFeatureHS *OGRFeatureH;
-typedef struct OGRStyleTableHS *OGRStyleTableH;
-#else
-/** Opaque type for a field definition (OGRFieldDefn) */
-typedef void *OGRFieldDefnH;
-/** Opaque type for a feature definition (OGRFeatureDefn) */
-typedef void *OGRFeatureDefnH;
-/** Opaque type for a feature (OGRFeature) */
-typedef void *OGRFeatureH;
-/** Opaque type for a style table (OGRStyleTable) */
-typedef void *OGRStyleTableH;
-#endif
-/** Opaque type for a geometry field definition (OGRGeomFieldDefn) */
-typedef struct OGRGeomFieldDefnHS *OGRGeomFieldDefnH;
-
-/** Opaque type for a field domain definition (OGRFieldDomain) */
-typedef struct OGRFieldDomainHS *OGRFieldDomainH;
-#endif /* DEFINE_OGRFeatureH */
-
 /* OGRFieldDefn */
 
 OGRFieldDefnH CPL_DLL OGR_Fld_Create(const char *,
@@ -668,19 +602,6 @@ const char CPL_DLL *OGR_GlobFldDomain_GetGlob(OGRFieldDomainH);
 /*      ogrsf_frmts.h                                                   */
 /* -------------------------------------------------------------------- */
 
-#if defined(DEBUG) || defined(GDAL_DEBUG)
-typedef struct OGRLayerHS *OGRLayerH;
-typedef struct OGRDataSourceHS *OGRDataSourceH;
-typedef struct OGRDriverHS *OGRSFDriverH;
-#else
-/** Opaque type for a layer (OGRLayer) */
-typedef void *OGRLayerH;
-/** Opaque type for a OGR datasource (OGRDataSource) */
-typedef void *OGRDataSourceH;
-/** Opaque type for a OGR driver (OGRSFDriver) */
-typedef void *OGRSFDriverH;
-#endif
-
 /* OGRLayer */
 
 const char CPL_DLL *OGR_L_GetName(OGRLayerH);
@@ -950,16 +871,6 @@ void CPL_DLL OGRCleanupAll(void);
 /*      ogrsf_featurestyle.h                                            */
 /* -------------------------------------------------------------------- */
 
-#if defined(DEBUG) || defined(GDAL_DEBUG)
-typedef struct OGRStyleMgrHS *OGRStyleMgrH;
-typedef struct OGRStyleToolHS *OGRStyleToolH;
-#else
-/** Style manager opaque type */
-typedef void *OGRStyleMgrH;
-/** Style tool opaque type */
-typedef void *OGRStyleToolH;
-#endif
-
 /* OGRStyleMgr */
 
 OGRStyleMgrH CPL_DLL OGR_SM_Create(OGRStyleTableH hStyleTable)
diff --git a/ogr/ogr_feature.h b/ogr/ogr_feature.h
index cf8c3a84d6b3..b8004bc2ccec 100644
--- a/ogr/ogr_feature.h
+++ b/ogr/ogr_feature.h
@@ -15,6 +15,7 @@
 #define OGR_FEATURE_H_INCLUDED
 
 #include "cpl_atomic_ops.h"
+#include "gdal_fwd.h"
 #include "ogr_featurestyle.h"
 #include "ogr_geometry.h"
 #include "ogr_geomcoordinateprecision.h"
@@ -32,32 +33,6 @@
  * Simple feature classes.
  */
 
-#ifndef DEFINE_OGRFeatureH
-/*! @cond Doxygen_Suppress */
-#define DEFINE_OGRFeatureH
-/*! @endcond */
-#if defined(DEBUG) || defined(GDAL_DEBUG)
-typedef struct OGRFieldDefnHS *OGRFieldDefnH;
-typedef struct OGRFeatureDefnHS *OGRFeatureDefnH;
-typedef struct OGRFeatureHS *OGRFeatureH;
-typedef struct OGRStyleTableHS *OGRStyleTableH;
-#else
-/** Opaque type for a field definition (OGRFieldDefn) */
-typedef void *OGRFieldDefnH;
-/** Opaque type for a feature definition (OGRFeatureDefn) */
-typedef void *OGRFeatureDefnH;
-/** Opaque type for a feature (OGRFeature) */
-typedef void *OGRFeatureH;
-/** Opaque type for a style table (OGRStyleTable) */
-typedef void *OGRStyleTableH;
-#endif
-/** Opaque type for a geometry field definition (OGRGeomFieldDefn) */
-typedef struct OGRGeomFieldDefnHS *OGRGeomFieldDefnH;
-
-/** Opaque type for a field domain definition (OGRFieldDomain) */
-typedef struct OGRFieldDomainHS *OGRFieldDomainH;
-#endif /* DEFINE_OGRFeatureH */
-
 class OGRStyleTable;
 
 /************************************************************************/
diff --git a/ogr/ogr_geometry.h b/ogr/ogr_geometry.h
index 414d5d2829b4..a8d6c1145a09 100644
--- a/ogr/ogr_geometry.h
+++ b/ogr/ogr_geometry.h
@@ -17,6 +17,7 @@
 
 #include "cpl_conv.h"
 #include "cpl_json.h"
+#include "gdal_fwd.h"
 #include "ogr_core.h"
 #include "ogr_geomcoordinateprecision.h"
 #include "ogr_spatialref.h"
@@ -32,17 +33,6 @@
  * Simple feature geometry classes.
  */
 
-/*! @cond Doxygen_Suppress */
-#ifndef DEFINEH_OGRGeometryH
-#define DEFINEH_OGRGeometryH
-#if defined(DEBUG) || defined(GDAL_DEBUG)
-typedef struct OGRGeometryHS *OGRGeometryH;
-#else
-typedef void *OGRGeometryH;
-#endif
-#endif /* DEFINEH_OGRGeometryH */
-/*! @endcond */
-
 /// WKT Output formatting options.
 enum class OGRWktFormat
 {
diff --git a/ogr/ogr_srs_api.h b/ogr/ogr_srs_api.h
index d2c6a5386d12..7e477c88b049 100644
--- a/ogr/ogr_srs_api.h
+++ b/ogr/ogr_srs_api.h
@@ -18,6 +18,7 @@
 
 #ifndef SWIG
 #include "ogr_core.h"
+#include "gdal_fwd.h"
 
 CPL_C_START
 
@@ -420,22 +421,6 @@ const char CPL_DLL *OSRAxisEnumToName(OGRAxisOrientation eOrientation);
 /* -------------------------------------------------------------------- */
 /*      C Wrappers for C++ objects and methods.                         */
 /* -------------------------------------------------------------------- */
-#ifndef DEFINED_OGRSpatialReferenceH
-/*! @cond Doxygen_Suppress */
-#define DEFINED_OGRSpatialReferenceH
-/*! @endcond */
-
-#if defined(DEBUG) || defined(GDAL_DEBUG)
-typedef struct OGRSpatialReferenceHS *OGRSpatialReferenceH;
-typedef struct OGRCoordinateTransformationHS *OGRCoordinateTransformationH;
-#else
-/** Opaque type for a Spatial Reference object */
-typedef void *OGRSpatialReferenceH;
-/** Opaque type for a coordinate transformation object */
-typedef void *OGRCoordinateTransformationH;
-#endif
-
-#endif
 
 void CPL_DLL OSRSetPROJSearchPaths(const char *const *papszPaths);
 char CPL_DLL **OSRGetPROJSearchPaths(void);
@@ -1012,10 +997,6 @@ char CPL_DLL **OSRGetAuthorityListFromDatabase(void);
 OGRCoordinateTransformationH CPL_DLL CPL_STDCALL OCTNewCoordinateTransformation(
     OGRSpatialReferenceH hSourceSRS, OGRSpatialReferenceH hTargetSRS);
 
-/** Coordinate transformation options. */
-typedef struct OGRCoordinateTransformationOptions
-    *OGRCoordinateTransformationOptionsH;
-
 OGRCoordinateTransformationOptionsH CPL_DLL
 OCTNewCoordinateTransformationOptions(void);