"The Death of Superman" is one of the most important landmark stories in the Man of Steel's publication history, as well as mainstream superhero comic books in general. The titanic event drew attention from people outside the usual comic book readership and helped revitalize the Superman comic book line in the early '90s. But outside of its major impact, the story also introduced Superman's deadliest and most bloodthirsty villain, Doomsday.
Like the Man of Steel, Doomsday would meet his end in The Death of Superman. This wouldn't stop the killing machine, however, and once Superman came back from the dead, his nemesis would soon do the same. Doomsday's return in 1994 was one of several times that the monster came back, and Superman's killer has stayed out of the grave ever since.
Superman/Doomsday: Hunter/Prey
After Superman's death, he was subsequently "replaced" by four other Supermen. The only one that truly claimed to be the real Man of Steel, though, was Cyborg Superman, who chained Doomsday's lifeless body to an asteroid and put it on a trajectory in which it would never land on another planet again. But Doomsday was eventually intercepted by a ship making its way to Apokolips. In Dan Jurgens and Brett Breeding's Superman/Doomsday: Hunter/Prey, this brought the now rested and revived villain into conflict with Darkseid himself, and even Uxas' Omega Beams were unable to defeat the creature. Without the strength of the dark world's leader, Desaad was forced to contact Earth, and Superman came to the planet via Boom Tube.
Superman was informed of Doomsday's history by the time-traveling Waverider and realized that he would be unable to kill Doomsday again due to his adaptive powers. Even with the advanced technology and weapons given to him, the Man of Steel was no match for the newer, stronger Doomsday. With no other way of defeating him, Superman used a time travel device to strand Doomsday at the end of time.
The Doomsday Wars
This still wasn't the end of Doomsday, though, as he would become rather frequent in the '90s despite his initial deadly nature. The first time this happened was when a scientist named Julian Lazarus created a duplicate of several supposedly deceased figures in the DC Universe. These included not only Doomsday but also the Barry Allen version of the Flash and the Green Lantern villain Sinestro.
His next appearance was in Jurgens and Norm Rapmund's Superman: The Doomsday Wars in 1998, where he was recovered from the end of time by a servant of one of Superman's other arch-foes, Brainiac. The Coluan scientist planned to transfer his consciousness into the creature's body, using the combination of brains and brawn to permanently defeat the Last Son of Krypton. Unfortunately, his mind was too bestial and violent for even Brainiac to override, force the villain to plan to mutate a cloned body of the monster he would be able to control. The host for this dark premise was meant to be Clark Ross, the newborn son of Pete Ross and Lana Lang.
Brainiac, having some control over Doomsday's body, managed to kidnap the child, but his plan was quickly intercepted by Superman. The Man of Steel promptly removed Brainiac's limited control over Doomsday, all before coming up with a seemingly permanent way to contain the beast. Superman trapped Doomsday in four different JLA transporters, never letting him materialize completely in any of them to escape.
Doomsday would continue to be freed from containment, killed and reborn in subsequent stories in the next several years. One such story even saw Lex Luthor free him to combat the even greater threat of Imperiex, only for the cosmic conqueror to obliterate the monster into dust. Since then, he's been a staunch part of Superman's rogues gallery, remaining a fearsome and murderous part of collectibles, toys, comic books, video games, cartoons and movies.