The Ultimate Killing Machine – BvS 101: Doomsday
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In the final BvS 101 to go with Batman v Superman: Dawn of Justice, Jason Inman takes a look at Doomsday. Originally created back in 1992 to kill the Man of Steel, the backstory of the character didn't come until much later. But his backstory makes him a bit more sympathetic and what was called for originally was just an unstoppable force that had to die.
This does not explain why he looks like a cave troll in the film.