Unstoppable rage. You can't reason with it. It's only purpose is destruction and death!
~ The Death of Superman tagline about Doomsday
Amazing. A creature who's traveled light years through space and survived a catastrophic entry to Earth. The Blue Bog Scout could have some competition.
~ Lex Luthor talking about Doomsday.
Doomsday is the main antagonist of the DC Animated Movie Universe film, The Death of Superman and a posthumous antagonist in Reign of the Supermen and Justice League Dark: Apokolips War. Doomsday was a living biological weapon created by Darkseid and was sent to Earth through a Boom Tube to kill the strongest beings on Earth, like Superman and the Justice League to pave the way for an invasion.
At some point, Darkseid had created Doomsday as a weapon using Kryptonian DNA and solar energy for one singular purpose: To wipe out all life on Earth and kill Superman for Darkseid. Darkseid then indoctrinated Doomsday into despising Superman before encasing him inside an asteroid that he had launched onto Earth via a Boom-Tube.
Hank Henshaw's crew then received a transmission saying that an asteroid containing Doomsday was going to hit the Excalibur space shuttle unless Henshaw and the crew escaped, unaware that they were being monitored by Lex Luthor. Henshaw believed that Superman would come to rescue him and his crew from the asteroid, but meteorites from the asteroid begin to hit the shuttle, killing the crew and Terri, leaving only Henshaw left. The asteroid then crashed against the ship, destroying the shuttle and killing Henshaw upon re-entry.
The asteroid then crash-landed in the Atlantic Ocean, both Lex Luthor and Aquaman sent people in to investigate the crash. However, Doomsday soon broke loose and began to immediately kill the Aquaman's Atlantean soldiers and the Luthor's exploration team. Arriving at the surface, Doomsday then goes on a killing spree slaughtering any living thing he came in contact with including a grizzly bear and two young campers in the woods. As Doomsday heads for Metropolis, he is confronted by the police, however, Doomsday kills all the police officers. Eventually, the Justice League arrives and Martian Manhunter’s telepathy reveals the creature to be a living weapon full of rage and is designed to annihilate entire civilizations. Even with their combined efforts, Doomsday brutally beats the Justice League, except Wonder Woman being the last Leaguer standing until Doomsday defeats her too and was about to kill her with her broken sword until Superman came to the rescue.
Superman and Doomsday began to fight an incredible battle throughout Metropolis. However despite Superman’s best efforts Doomsday slowly manages to overpower Superman. Lois Lane, reporting live by helicopter with her cameraman, Jimmy Olsen, is spotted by Doomsday and he prepares to destroy the helicopter until Superman stops Doomsday and saves Lois and Jimmy. Soon enough, a battle-suited Lex Luthor joins the fight against Doomsday, aiming to become Metropolis’ "true savior," but he is incapacitated and saved by Superman. Their battle eventually ended up in the Hall of Justice which left the Hall destroyed.
Doomsday emerged from the rubble wrapping Superman's cape around his neck repeatedly stomping on his head on the ground. Realizing the toll the battle has taken on Superman, Lois attempts to sacrifice herself to Doomsday by throwing stones at the creature to distract it. As Doomsday prepares to kill Lois with her final words being, "I got your note and I love you too," Superman at the last moment drew all the strength that he had left and hurls himself directly at Doomsday and breaks his neck, but is fatally stabbed in the chest with one of his bone claws, and dies in Lois’ arms.
At S.T.A.R. Labs, Doomsday's body was then taken into custody where days later, an exonerated Lex Luthor attempted to gain custody of Doomsday's body for Project Cadmus for examination and research purposes, but the STAR Labs director, Doctor Corbow refused Lex's request telling him that they will keep Doomsday's body until the government can launch it into space. At the time they talking, Superman's rocket suddenly self-starts and flies away.
To Be Added..
In the comics, Doomsday is an unkillable and virtually unstoppable monster who despises all life and desires to eradicate it. He was experimented on as an infant by a scientist named Bertron who wanted to create the ultimate lifeform by adapting it to survive in any environment no matter how hostile. He also is infamous for being one of the only villains in DC history that have successfully killed Superman but was also killed too. He was later revived and became a frequent enemy of Superman and the Justice League.