Willis O'Brien was an early pioneer of stop motion animation, creating animated films using three-dimensional puppet figures. He is most famous for his work animating the original King Kong film. Nick Park creates stop motion clay animation films using Aardman Animation's techniques, best known for the Wallace and Gromit and Shaun the Sheep films. Rear projection and claymation both have advantages and disadvantages for animation. Rear projection allows for large screen sizes but has issues with lamp replacement costs and space usage. Claymation allows for character morphing but is very time consuming and difficult to create detailed characters.