Originally known as "The Ultimate", Doomsday was born in prehistoric times on Krypton, long before the humanoid Kryptonian race gained dominance over the planet about 250,000 years ago. It was at that time a violent, hellish world, where only the absolute strongest of creatures could survive. In a cruel experiment involving evolution, intended to create the perfect living being, the alien scientist Bertron released a humanoid infant (born in vitro in a lab) onto the surface of the planet, where he was promptly killed by the harsh environment. The baby's remains were collected and used to clone a stronger version. This process was repeated over and over for decades as a form of accelerated natural evolution. The agony of these repeated deaths was recorded in his genes, driving the creature to hate all life.