Bertron

Bertron was an ancient alien scientist and a villain from DC comics who was responsible for the creation of Doomsday, he is probably one of DC's most repugnant villains ever as he not only created a near-unstoppable monster but did so in a manner so utterly barbaric it rivalled even the actions of cosmic despots such as Darkseid.

Bertron's experiments where intended to create the "perfect" life form and involved him releasing a humanoid infant onto a primordial Krypton, which killed the baby due to its hostile environment - Bertron then cloned the infant and continually released it back onto Krypton where it died in agony, over and over.. each time Bertron brought it back he made it slightly stronger but also made sure every moment of its former life was coded into its genes : this meant Doomsday remembered every death it suffered and grew to hate life as a result.

Eventually Bertron's madness succeeded and Doomsday evolved to survive Krypton and went on a rampage, killing all of Krypton's ancient predators before pursuing Bertron and murdering its creator (and tormentor) once and for all.

Unfortunately for the universe Bertron's legacy would continue as Doomsday went on a universal crusade to murder life, having been driven insane by Bertron's cruelty.