Doomsday

Doomsday is an incredibly powerful monster with regenerative abilities. Every time he dies he respawns having evolved past the last thing that killed him, making him slowly invulnerable over the course of centuries traveling the universe. Developed as a weapon in a facility by the scientist Bertron, he was tested out through many of his first deaths on the planet Krypton, giving him an immense natural hatred towards Kryptonians. During the Death of Superman storyline he actually killed Superman, although Superman delivered a killing blow against him simultaneously. They would both return to fight many more times. He has been involved with the Suicide Squad and the Secret Society of Super-Villains. Doomsday was created by Dan Jurgens, Jerry Ordway, Roger Stern, Louise Simonson, and Brett Breeding first appearing in Superman: The Man of Steel #17. (1992)