DoomsdayA brutal rampaging monster who emerged from nowhere (later revealed to be Krypton). Possessing enormous super strength, speed, invulnerability and regeneration, he carved an unstoppable path of destruction from the Midwest to Metropolis, where Superman finally ended his progress while the two battled to their mutual deaths. They both got better, Superman thanks to Kryptonian technology and Doomsday because his regenerative abilities are specifically engineered to be that good (including the ability to adapt new defenses for anything that has killed him.)
The SupermenFollowing Superman's death and funeral, four men showed up around the same time, all bearing the mantle of Superman. Three of the four were claiming to be him (or his clone). DC Comics gave each of them one of Superman's 4 monthly titles to one of these characters for the duration of this story arc though they did crossover frequently especially towards the end when the real Superman returned.
Man Of TomorrowThe most credible of the Supermen. The Cyborg Superman returned with the seeming character, purpose, powers and competence of the original and was given the thumbs up by Superman's de facto doctor Emil Hamilton and President Clinton (whom had delivered his eulogy). He even seemed to remember scraps of Superman's life. When Coast City was destroyed, he was the first at the scenes leading cleanup because "nobody else could survive this." Except, it was not as it seemed.In fact, he was an astronaut known as Hank Henshaw who, along with three others was bombarded by radiation on a spaceflight. When they returned to Earth, they had all gained superpowers, but Henshaw was the only one to survive, having been transformed into a being of pure energy with the ability to co-opt and transform machinery. Superman trapped Henshaw in his own birthing matrix, believing Kryptonian technology would be too complex for Henshaw to figure out. Superman was wrong; Henshaw was able to use traces of Superman's DNA and his technology to build a cybernetic Kryptonian body. At least that's how he remembers it. In truth, Henshaw himself hijacked Superman's birthing matrix and fled Earth, but his madness caused him to misremember this event. He made an alliance with longtime Superman nemesis Mongul to conquer Earth and turn it into a new War World, making him the chief antagonist Superman must face upon his return (these events also led to Hal Jordan's Heroic BSOD (see the Green Lantern page for more on that).
SuperboyThis storyline introduced the current Kon-El version of Superboy. After Superman's death, Project Cadmus tried to create a clone of Superman and, failing that, created a being that could approximate some of his powers. The accelerated maturity process meant to make the clone the same age as Superman was halted by the Newsboy Legion who broke him out while in the teenage phase of his development.During this series, he insisted on being called Superman to the point that his manager secured rights to the name, and he adopted a Totally Radical image to suit his age. He ended up being instrumental in saving Metropolis when the Cyborg attacked. After Superman returned, Superboy basically had no choice but to relinquish the name and take the name Superboy (a talk from the real McCoy helped soften the blow).
The Man of SteelHenry Johnson was a construction worker who was once saved by Superman. When Superman died, he decided to honor the Man of Steel... by building powered armor and taking to the streets. You see, Henry Johnson was actually John Henry Irons, a former weapons engineer who got out of the business when he saw the results of his work in the field. He used the Steel name to redeem his past, putting him into conflict with former Love Interest and fellow weapons engineer, the White Bunny, who had armed Metropolis' gangs with Irons' own BFG, the Toastmaster. Notably, he's the only one of the four to not try to claim he was Superman, but a psychic briefly teased at the idea that Superman's soul now resided in Irons' body (not true, it turns out).When the real Superman returned, Irons tagged along to help him stop the Cyborg's plot of world conquest and Superman dubbed him "Steel". The character would go on to continue his career for years, joining the Justice League during Morrison's run and serving as Superman's science advisor.
The Last Son of KryptonAfter Superman dies, we see the robots hard at work in the Fortress of Solitude regathering an essence. This reconstituted essence went to Superman's tomb and out came Superman, sort of. His powers were a bit different, he could fire energy blasts from his hands, his eyes were sensitive, requiring shades and he had to recharge using an energy chamber in the Fortress (unlike Superman, who stays charged from direct sunlight). But more importantly, he was cold, distant, and had a much more brutal stance on justice.If you're catching the pattern by now, it turns out he wasn't Superman either. He was the Eradicator, a supercomputer turned energy being bent on remaking Earth into Krypton, but this time around, he was confused and forgot his own identity, believing himself to actually be Superman. His body was built from part of Superman's grave, and the energy matrix was powered by the body of Superman himself, who was rejuvenated from his prolonged stay in it. The Eradicator would sacrifice himself to repower Superman at the end of this series and his body would eventually be passed onto to a terminally ill STAR Labs scientist.
Lex Luthor Jr.A young hirsute man with a full thick mane of hair who claimed the Luthor fortune when Luthor died in a plane crash. It turns out that Lex Luthor the second is actually the original Lex Luthor. After Kryptonite poisoning had given Lex cancer, he faked his own death in a plane crash and returned in a younger body (with a full head of red hair and beard), claiming to be his son. During this storyarc, he dated Supergirl (the Matrix version).
Supergirl (Matrix)Is featured prominently in the Death and Return storylines. While she tries, and fails, to help Superman defeat Doomsday, she more than makes up for it by keeping the peace in the interim and, thanks to her shapeshifting abilities, even helps Clark Kent conveniently return after Superman does (allowing Superman to save "Clark" from a collapsed building).
Jeb FriedmanLois Lane's ex-boyfriend. He shows up in this series to tempt Lois with the prospect of getting over Clark and hooking up with him. Given that her fiancee died a few weeks ago and she's still clearly emotionally distraught, you can take a guess at what kind of man he is.
Justice LeagueIf you were wondering where Superman's friends were during the struggle, they did try to help Superman and were all in turn injured or taken out of the fight. The consequences of their involvement followed some of them for years after the battle.
FireBasically, the Brazillian supermodel version of the Human Torch except with green fire. She lost her powers temporarily in the wake of this battle having expended all her available energy on the Beam Spam attack.
Ice MaidenMore commonly known as Ice. Guy Gardner's on again off again Love Interest and Fire's best friend. She and Fire came from an interational superhero team when the Justice League International formed.