Cooker is a gas cooker on wheels, complete with a coin slot and wonky antenna, is the patroller of the moon's surface. It is shocked to find Wallace and Gromit 'eating' the landscape, but upon discovering a holiday brochure becomes captivated by the idea of skiing.
After being unknowingly activated by Wallace with a coin, Cooker was surprised to find others on the moon. When he noticed Wallace was littering and placing his rocket on a forbidden parking spot, he tried to teach Wallace by hitting him with a police truncheon.
But before he could do so, the coin meter was used up and he stopped in the middle of the action. Upon seeing the motionless Cooker behind him, Wallace took away the truncheon and inserted another coin. Cooker reactivated and noticed Wallace and Gromit leaving to Earth, linking them to potentially taking him to Earth so he could ski, so Cooker followed them. Cooker went in to the base of the rocket and accidentally lit the high fuse which blew him off and launched the rocket.
After landing, Cooker was depressed at having failed to get into the rocket. Then he realised the metal strips that came off the rocket with him could be bent, so he decided to use the metal strips as skis and the various hills on the Moon as ski slopes. It works, and having fulfilled his ambition at last, he was last seen waving good-bye to the space travelers as they set off back to Earth.
- It is a mystery as to whom built Cooker and sent him to the Moon, to begin with.
- At the end of A Grand Day Out, Cooker is no longer an enemy to Wallace & Gromit.
- An audio adaptation of A Grand Day Out called Cooker the Moon Machine.