Ralph-O-Cop
Wikisimpsons - The Simpsons Wiki
Ralph-O-Cop was a robot that Homer faced in the Robot Rumbles. Owned by Chief Wiggum and his son, Ralph Wiggum, the robot rolled on tank treads, wore an officer's cap, had a picture of Ralph for its face, and it had one arm that stuck out straight and held a gun.
Homer grabbed the gun from him and shot Ralph-O-Cop in the head.