The Death of Superman/Characters

Doomsday
A brutal raging monster who emerged from nowhere (later revealed to be Krypton). Possesing enormous super strength, speed, invulnerability and regeneration, he carved an unstoppable path of destruction from the midwest to Metropolis where Superman finally checked his progress while the two battled to 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.)
 * You Fail Biology Forever: In the sequel, it turns out that Doomsday was created by sending clones of the same baby out into a harsh environment over and over again until it adapts. There's no hint of anything like tinkering with the clone's genes to help it adapt or even sending out multiple clones simultaneously and basing the next generation on the most viable baby of the last generation making this a really inefficient way to "evolve" the ultimate life form.
 * Generic Doomsday Villain: May as well be the trope namer.
 * He is the Trope Namer.
 * Implacable Man: As mentioned above, he's stronger and tougher than Superman and almost as fast. But if you can hit him hard enough for it to hurt, he'll just regenerate. Even death doesn't stop this regeneration.
 * Ultimate Lifeform: Pretty much.
 * Villain Decay: Though not till well after this series.

The Supermen
Following 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 one of each 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 Tomorrow
The 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 astronaut Hank Henshaw who, along with three others was bombarded by radiation on a spaceflight. When they returned to earth, they all had powers 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. Superman was wrong, and 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 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.)

Superboy
This 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.)
 * Berserk Button: Calling him Superboy, prior to the end of this series.
 * Cloning Blues: Features heavily in his character.
 * Flying Brick: At first, he fits the trope perfectly having only those specific powers, later it turns out that he really has one power, "Tactile Kinesis" which he's been using to simulate the flying brick powers but has other applications.
 * Half-Human Hybrid: More the truth when he's retconned later on. At first he's a genetically modified clone of a human patterning a few Kryptonian traits and modified to look like Superman, later it was decided that Superboy is the clone of Lex Luthor and Superman. Though it does make sense as Lex had a working relationship with Cadmus from when they'd created a clone body for him.
 * Totally Radical: Superboy's original look was a leather biker jacket, a surfer cut, shades, earrings, unnecessary straps and buckles and gloves, though the tights underneath were pretty standard. Naturally this meant he needed to frequently update his look. More recently, he's settled on the less trendy T-shirt and jeans look with buzzed hair he sports today.
 * Younger and Hipper: Superboy along with the others, was originally a parody of then current trends in comic books as applied to Superman. He's grown beyond that.

The Man of Steel
Henry 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 Iron's body (not true, it turns out.)

When the real Superman returned, Iron's 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.
 * Badass Normal: In his very first appearance, Irons is shown as a six and a half foot tall hulking mass of muscle able to manhandle heavily armed thugs with his barehands before the Powered Armor.
 * Foe Yay: With White Bunny. They used to date and some early scenes show that Irons and Bunny have a little residual attraction.
 * Genius Bruiser: Irons is this by human standards. Powerfully built enough to manhandle thugs and smart enough to design and create cutting edge weaponry (later, he's shown to have a pretty broad scientific and engineering background.)
 * Legacy Character: Originally this is what he was trying to be for Superman.

The Last Son of Krypton
After 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.
 * Anti-Hero: He has the mind of a cold logical Kryptonian supercomputer and the body of Superman, except his powers lend themselves to a higher ratio of collateral damage. Be afraid criminals, be very afraid.
 * Redemption Equals Death: The Eradicator sacrificed himself so that a Kryptonite blast meant to kill Superman would be altered to power Superman up leaving him fully charged to defeat the now weakened Cyborg.

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 Lex Luthor the first. After Kryptonite poisoning had given Lex cancer, he faked his own death in a plane crash and returned in a younger body 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. She 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.)
 * Dating Catwoman: An inversion in that Lex Luthor Jr is dating Supergirl during this series and Supergirl does not know that he's the original Lex.
 * Mythology Gag: When Superman returns at diminished power level and storms Engine City, Supergirl serves as his "Secret Weapon." This is a reference to the original Supergirl's status during the first several years of her existence when Superman wanted to hold off on revealing his cousin to the world.

Jeb Friedman
Lois 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 League
If 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.
 * Beam Spam- All the Leaguers involved in the battle had energy blasting powers of some sort. They tried a combined attack leading too ..
 * No One Could Survive That-Doomsday is hit simultaneously by full intensity Heat Vision, Martian Vision, Power Ring Blasts, Fire, Ice, and other energy blasts. Not only did Doomsday not fall, he wasn't even scratched. In fact, all they accomplished was the weakening of his remaining restraints, freeing his other arm.

Booster Gold
His suit was shredded during this battle. Afterwards, he used Powered Armor for several years.

Blue Beetle
Put in a coma

Guy Gardner
Probably fared best. At the time, he was wielding Sinestro's ring. He also briefly endorsed the Eradicator when he was claiming to be Superman.

Bloodwynd
A mysterious character with the supposed ability to draw on the spirits of the dead to grant him flight, strength, eye beams and teleportation. It would later turn out that this was Martian Manhunter in a confused state (and even later still, it would turn out that there was a real Bloodwynd he had made a connection with).

Fire
Basically, 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 Maiden
More 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.