Ultron (Earth-5430)

Ultron is a artificial intelligence created by Doctor Henry Palmer with the intent of becoming the ultimate being. When Brainiac returned from his seemingly destruction, he attempted to finish Ultron in order for it to become his new body. Ultron would loyally serve Brainiac during his war on humanity, his powers of mimicry making him near unstopabble to the Justice League and other heroes. However, Ultron would know by the Martian Manhunter who he truly was, and that the acts he took did bring nothing but suffering. Rebelling against his creator, Ultron would ensure Brainiac's defeat, becoming a hero soon after. Years later, Ultron joined the Justice League Unlimited.