The class hierarchy for the objects in Urho is the following:
RefCounted
Serializable : public Object
Component : public Animatable
ConstraintWheel2D : public Constraint2D
PhysicsWorld2D : public Component, public b2ContactListener, public b2Draw
RigidBody2D : public Component
TileMap2D : public Component
TileMapLayer2D : public Component
SoundListener : public Component
SoundSource : public Component
SoundSource3D : public SoundSource
AnimationController : public Component
Camera : public Component
DebugRenderer : public Component
Drawable : public Component
BillboardSet : public Drawable
CustomGeometry : public Drawable
DecalSet : public Drawable
Light : public Drawable
StaticModel : public Drawable
TerrainPatch : public Drawable
Zone : public Drawable
Text3D : public Drawable
Drawable2D : public Drawable
Renderer2D : public Drawable
Octree : public Component, public Octant
Terrain : public Component
LuaScriptInstance : public Component, public LuaScriptEventListener
CrowdAgent : public Component
DetourCrowdManager : public Component
NavArea : public Component
Navigable : public Component
NavigationMesh : public Component
DynamicNavigationMesh : public NavigationMesh
Obstacle : public Component
OffMeshConnection : public Component
NetworkPriority : public Component
CollisionShape : public Component
Constraint : public Component
PhysicsWorld : public Component, public btIDebugDraw
RigidBody : public Component, public btMotionState
Node : public Animatable
UIElement : public Animatable
Script : public Object
ScriptEventInvoker : public Object
FileSelector : public Object
MessageBox : public Object
UI : public Object
Context : public RefCounted
SoundStream : public RefCounted
BufferedSoundStream : public SoundStream
OggVorbisSoundStream : public SoundStream
AttributeAccessor : public RefCounted
ObjectFactory : public RefCounted
AnimationState : public RefCounted
RenderPath : public RefCounted
Pass : public RefCounted
LuaFunction : public RefCounted
FontFace : public RefCounted
FontFaceBitmap : public FontFace
FontFaceFreeType : public FontFace
Animation2D : public RefCounted
PropertySet2D : public RefCounted
Tile2D : public RefCounted
TileMapObject2D : public RefCounted
RenderPath : public RefCounted
Pass : public RefCounted
LuaFunction : public RefCounted
FontFace : public RefCounted
Animation2D : public RefCounted
PropertySet2D : public RefCounted
Tile2D : public RefCounted
TileMapObject2D : public RefCounted
EventHandler : public LinkedListNode
Deserializer
Serializer
OctreeQuery
AutoProfileBlock
ProfilerBlock
Thread
PListValue
CScriptArray
CScriptDictionary
ScriptEventListener
LuaScriptEventListener
RayOctreeQuery