Since Doomsday’s debut in The Death of Superman event in the 90s’, creators have experimented with the monster’s backstory. Over time, it became clear that the origin story of Superman’s killer is best left a mystery.
When the monstrosity that is Doomsday first appeared in Superman: The Man of Steel #17, his true form was concealed by a green uniform. As his rampage progressed, the costume tore with his increasing rage, revealing spikes protruding from his fists. Since he first leveled multiple cities and destroyed Metropolis, writers have expanded on his origins. As a result of genetic mutations on Krypton, Doomsday was practically bred for war. In Superman/Doomsday: Hunter/Prey written by Dan Jurgens, a mad scientist known as “Bertron” is revealed to be the beast’s creator. The story elaborated on what turned Doomsday into the only being capable of killing Superman. Many stories have similarly attempted to elaborate on the monster’s beginnings.
However, it seems that Doomsday's origins are best left a mystery. As creators were pitching The Death of Superman storyline, it was important for the monster to not take too much of the focus away from the events taking place. The strange sense of mystery and terror surrounding Doomsday added tension to a story which was simple on its face. Breaking out of his imprisonment from deep beneath the Earth’s surface, Doomsday came from nowhere and seemed confused when he interacted with the outside world.
Showing up in his green uniform with red lenses, his nondescript appearance raised many questions. The fact that such an anonymous being had seemingly existed for a long time, and was able to take down the world’s most powerful superhero elevated his threat. Similar to the Joker, Doomsday has proven that he works without any defined history. Stories which have delved into the beast’s origins have ascribed him motivations that boil down to programming beyond his control. The most compelling characters are elevated by personal reasonings to do what they do.
Instead of enriching the villain, writers have further relegated him to functioning as a plot device, when his main use as Superman’s killer has been long past. With a story that drastically altered the DC Universe’s status quo, Doomsday’s side of things doesn’t need to be overly complicated. Other media outside of comics such as Batman v Superman: Dawn of Justice and the DC Animated Universe took similar approaches, with the monster being programmed to kill the Man of Steel. Doomsday’s most impactful appearances have left him to speak through his actions, revealing that any backstory is irrelevant so long as he’s wreaking havoc.