He-Man and the Masters of the Universe (1983)

S02E48 Happy Birthday Roboto

He-Man and Man-At-Arms stumble upon a downed spaceship inhabited by a robot. They bring the robot back to the palace, where Man-At-Arms successfully repairs him. The robot introduces himself as Roboto, a space explorer from the planet Robotica, eager to discover the wonders of Eternia. However, during the night, Modulok, Man-At-Arms' arch-nemesis, captures Roboto. Modulok reprograms him to carry out his sinister plans, which include the horrifying scheme of transplanting Man-At-Arms' brain into one of Modulok's extra heads.