Doomsday is the name of a fictional supervillain in the Superman comic book series.

Origin
Doomsday was artificially created by Bertron, a mad scientist working on Krypton, Superman's home world, though neither he nor his creator were Kryptonian (although Bertron had used a cadre of Kryptonian scientists who assisted him in his lab). Doomsday hated Superman because whenever he looked at a Kryptonian, he saw his creator who had subjected him to death over and over again in order to create the perfect life form. In order to do this, they sent a baby onto the surface of Krypton, where it would be killed by the harsh environment or vicious creatures. Each time, the lifeform's remains were harvested and used again, to create a better, stronger version of the last. Through decades of this process, the being which would eventually become Doomsday was forced to endure the agony of death, thousands upon thousands of times; the memory of these countless deaths drove it to hate all life, and especially Kryptonians.

History
Doomsday was created in 1992 by writer/artist Dan Jurgens for a story arc in the Superman series of comic books that was titled The Death of Superman. In this series, Doomsday was an ultra-powerful destructive villain who engaged in a seemingly endless, mindless rampage across the face of the United States. He had been buried underground for an unknown period of time at the beginning of the story arc, until he tunneled his way out and into the light of day. He immediately began attacking anything and everything within range, with the mindless ferocity of a monster, never speaking, and apparently enjoying the wanton destruction and mayhem he was causing.

In his first encounter with the Justice League, Doomsday defeated the entire team of superheroes in a matter of minutes, laying waste to the entire surrounding area, and finally attracting the attention of Superman. (Because he never spoke, he never called himself "Doomsday." The name "Doomsday" was coined by Booster Gold, one of the members of the Justice League, who said that the monster's rampage resembled "the arrival of Doomsday," meaning the end of the world.) Superman quickly found that Doomsday's awesome power was easily a match for his own, and he realized that if Doomsday reached the city of Metropolis, the resulting battle could conceivably destroy the city and kill millions of innocent people.

In the space of only a few issues of the Superman comic book series, Superman and Doomsday engaged in a titanic, no-holds-barred battle that made Superman realize that Doomsday would continue to attack relentlessly, unending, with no defeat or surrender in sight. It culminated in Superman #75, where in a heroic act of self-sacrifice, Superman fought Doomsday to the bitter end, until the two combatants struck a simultaneous, fatal blow that left both combatants lifeless.

In the aftermath of Superman's apparent death, no less than four super-beings appeared in his wake, all of them declaring themselves to be the "real" Superman. One of these four, a half-man/half-machine cyborg (who would later become a dangerous villain called simply "The Cyborg") took the apparently lifeless body of Doomsday and flung it into deep space, on a trajectory that would supposedly ensure that it would never land on any planet.

However, Doomsday's body was found by a deep-space scavenger ship that happened to be en route to Apokolips, the home of the evil Darkseid. During this trip it was learned that Doomsday was not really dead. He revived and, after slaughtering the crew of the salvage ship, found himself on the harsh world of Apokolips. This was to be the setup for a final showdown between Doomsday and Superman, who had been uneasy about the possibility of Doomsday's resurrection. Unfortunately, Darkseid's servant DeSaad opened a boom tube to Caltron-- the first world where Doomsday was successfully defeated -- and sent Doomsday through to what DeSaad believed was his defeat at the hands of the Radiant.

Doomsday is essentially able to adapt and overcome any opponent, so although the Radiant had defeated him once, he would not be able to defeat him again. Superman refused to heed this warning and allow Caltron to be destroyed. He fought Doomsday again with the help of a Mother Box, a thinking computer, but he met with defeat. He was forced to use one of Waverider's time travel devices to bring Doomsday to the one place where nothing can survive: the end of time.

Doomsday returned yet again in the miniseries The Doomsday Wars. In this series, Brainiac uses his technology to travel to the end of time to retrieve Doomsday in order to combine the beast's massive power with Brainiac's formidible intellect. Doomsday's will proves too strong to override completely with psionics, so Brainiac attempts to use a human host to genetically engineer a Doomsday body without the mindless rage. He chooses to use Pete Ross and Lana Lang's newborn baby. Superman thwarts Brainiac's plot with one of the villain's own devices, and places Doomsday in kind of stasis with four JLA teleporters.

Following these events, Doomsday was released by Lex Luthor's Suicide Squad to battle Imperiex, a threat that was judged to be even greater than Doomsday himself. Once freed, Doomsday slaughtered the Squad, and then went on to battle Imperiex's numerous probes, which had thus far managed to seriously injure or kill most of Earth's heroes. Doomsday tore through numerous probes with seemingly little effort before finally, confronting Imperiex himself. Imperiex proved too much for Doomsday, and blasted him, reducing Doomsday to a skeleton. Eventually, Doomsday's body was retrieved and his flesh regrown by Lex Luthor, who then handed Doomsday over to Darkseid to repay Earth's war debt to Apokolips. By this time, Doomsday had evolved intelligence. Darkseid attempted to replicate Doomsday, producing an army of Doomsday "clones." Fortunately, Darkseid was not able to perfectly duplicate the creature in all its raw power, possibly as a result of the creature's complex DNA.

When Superman travelled to Apokolips to reclaim the life of John Henry Irons, the man known as Steel, Darkseid's wife Mortalla ordered his troops to release Doomsday in an attempt to help Darkseid. Doomsday's short freedom was quickly halted by John Henry Irons in the Entropy Aegis, an armor with incredible power. Doomsday disappeared and was seen wandering the harsh lands of Apokolips.

With his newfound intelligence, Doomsday managed to escape Apokolips and return to Earth. From his arrival, Doomsday encountered a series of emotions previously alien to him - love, compassion and kindness. Exploring the full abilities of these new emotions, Doomsday made his way to Metropolis once more, though not in the destructive manner he had before. Upon his arrival in Metropolis, Doomsday found Superman at the brink of death at the hands of one of his enemies. Using his new emotions, Doomsday shocked both Superman and his opponent, Gog by helping Superman fight against Gog's army. This unfortunately was not enough to save Superman, who died at the hands of Gog and caused the future to diverge. In this new future, Doomsday was remembered as one of Earth's greatest heroes, who continued Superman's legacy by leading an army under his name against the army of Gog. This timeline ended when an old and weary Gog offered Doomsday the chance to return to the past and save Superman - albeit at the cost of becoming a monster again.

Doomsday's present whereabouts are unknown.


Doomsday in Other Media
In Justice League, the Justice Lords (a tyrannical version of the Justice League from a parallel universe) fought a weaker, more intelligent version of Doomsday (voiced by Michael Jay White). The situation was resolved by that version of Superman firing his heat vision into the villain's head, lobotomizing him. Later, it was revealed that the Cadmus Project had created this Doomsday as an imperfect clone of Superman, programmed to hate the Man of Steel. His brain eventually regenerated, and he resumed his quest to kill Superman. Like in the comics, this version of Doomsday seems to have a biology that adapts to any opponent given time, so any attack used to defeat him works only once: when he re-appeared after his laser-lobotomy, he had grown a heavy bone plate in his skull making it impossible to lobotomize him again. He was finally banished to the Phantom Zone as a last resort.