Metallo

John Corben was a professional con man until he was fatally injured in a car crash. The dying Corben was found by Professor Emmet Vale, a specialist in cybernetics, who was obsessed with the idea that Superman was the spearhead of an alien invasion after he discovered the ship that brought the infant Kal-El to earth and mistranslated a message from his father Jor-El to his son. Vale took the helpless Corben to his lab and transplanted his brain into a cyborg body powered by Uranium, to which upon awakening the cyborg, instructed him to kill Superman.

Metallo (named after the alloy his new form was made from) initially was enraged by what Vale had done to him, but feigned interest in the paranoiac doctor's findings of Kal-El's origins as well as his replacing the uranium core with Corben's new Kryptonite heart, a material deadly to Superman, to kill him with. After Vale had given Corben's bionic chasis a more humanized look, Metallo broke the Professor's neck, killing the scientist as he'd then outlived his usefulness, but nonetheless ended up battling Superman as per his recreation's purpose.