WARNING: This page contains spoilers!
The Clockwork Beast is a robot made by Klogg to protect the Castle. The beast is released by pressing a button in the Throne Room, and it comes from underground in a strange test tube-like container. He has a small patrol vehicle attached to his back called the Bear Retrieval Unit.
The Clockwork Beast is released to fight Big Robot Bil, who is being controlled by Klaymen. Willie knows about the beast and runs around in terror until he hits one of Bil's parts and passes out. The beast eventually sends out the Bear Retrieval Unit to steal Bil's teddy bear. He then destroys it, which encourages Bil to fight him. Bil eventually defeats him and attempts to kill Klogg. At this time Klaymen escapes from inside Bil. Klogg presses a button and shoots a cannonball in Bil's chest. This causes Bil to die and fall off the edge of the Neverhood, and Willie dies along with him, as he was inside Bil and did not come to until Bil was shot in the chest. Both Willie and Bil are resurrected in the Good Ending.
The Clockwork Beast is made out of used metal pieces and clock pieces. He has the Bear Retrieval Unit vehicle strapped to his back. In the game, it is actually made of pieces of plastic and metal.