Doomsday was the beast incarnate, a demon creature of nothing but pure rage. The creature was renowned for being one of few things in the world able to match feats with Superman. There was no emotion in Doomsday, although the creature strategized slightly, it was only so that it could kill better.
Created on Krypton, Doomsday was a monster of pure legend. Eventually legend became reality and Doomsday showed up on Krypton to raze the planet. However, he was stopped and tamed by Colonel Zod. Zod subsequently exiled the beast to the Phantom Zone. After Zod himself was exiled, Doomsday answered to him, showing such strength as to nearly be able to punch through dimensional walls.
Eventually Doomsday escaped and arrived on Earth, combating the Last Son of Krypton, the renowned Superman. The battle raged on for nearly a day, ending with Doomsday and Superman killing each other. Doomsday's body was later deposited back to the Phantom Zone. Though the Last Son was revived within the same year, Doomsday returned nearly four years later, causing a storm in the Norwegian Sea. He was released by Zod to weaken the Phantom Zone's interdimensional walls. There he confronted and attacked Wonder Woman, and disappeared shortly after breaking her arm. He was later found to have returned to the Phantom Zone, where he began aimlessly wandering in his Forbidden Zone.
Zod's damage was permanent as Doomsday was able to traverse in between the Phantom Zone and Earth once Xa-Du released him from the Forbidden Zone and the Tower from the Phantom Zone. However, he was no longer just a rampaging monster intent only on killing, but rather began to kill systematically. Doomsday's physical appearance also began to mutate around this time. Growing bigger, Doomsday began to absorb the life force of beings it attacked. This resulted in it growing stronger, although its main purpose was to grow strong enough to try and absorb Superman's life force. However, the Man of Steel got to it first and attacked it. In the ensuing battle, Superman killed Doomsday by ripping the unstoppable force in two.
Initially Doomsday was little more than brute force, a creature with enough power to physically kill Superman. However, after returning it gained a host of new powers, including being able to suck the life force out of a creature and teleport. These powers resulted in Doomsday affecting matter down to a molecular level, causing water to boil and sand to become black obsidian. Against foes that it did not need to kill through fighting, Doomsday could send out the Doomsday Virus to kill them in seconds. The range of the teleportation was vast, as Doomsday was able to get from Venus to Earth in a matter of minutes.