Aquaman: Once had a hand made of magic water. Came after the beard/hook hand phase, when they were trying to get him back to a more classic look instead of the dark age crap they got carried away with.
Ares: Tried to turn the second Wonder Girl (Cassandra Sandsmark) away from Wonder Woman's influence. He gave her a gift of godly lightning, and used his gift and her insecurities to prey on her and harm Wonder Woman.
Bane: After the conclusion of the overarching Knightfall storyline (his introduction), Bane resolved to get rid of his dependence on Venom and did so cold turkey. He saw it as a weakness of both body and mind, and expressed disgust with himself for having ever been dependent on it. He stayed this way until the New 52 reboot - almost 20 years of real life time.
Batgirl: Was Oracle for longer in real world time than she was Batgirl, alternate universe or discontinuous publications notwithstanding.
Batman: Killed criminals and sometimes carried a gun in his original appearances. He was later softened to have greater appeal, and then enormously softened in the Silver Age after the advent of the Comics Code.
Black Adam: Despite being a mortal man, Black Adam lived to be thousands of years old by virtually never reverting to his human form. As Adam, he is ageless, much like the gods - or any of the other Marvels, who turn back far more frequently.
Catwoman: Went to Italy with Riddler trying to track down someone who'd slighted her. In the process, she caught him trying on one of her Cat suits. Brrr.
Cyborg: Had nothing at all to do with the Justice League, ever, up until the New 52 reboot. Now he's playing the token negro role, because DC is behind understanding race and race relations in America by about thirty years.
Deathstroke: Has a knack for beating the shit out of speedsters. He once shot Kid Flash in the knee with a shotgun, which ended about the way you'd expect.
Doomsday: While he was originally of unknown origin, Doomsday was formed by genetic engineering on a prehistoric Krypton, millions of years ago by members of early intelligent civilization. He was created by being slowly crafted to survive some of the most hostile environments and most dangerous creatures in the universe, and tested by repeatedly being subjected to death at their hands and reanimation by his creator. He retains memory of this, however, and his malice over it is why he's hell bent on killing anything that moves.
Flash: Barry Allen was the beginning of comic book multiverses. He was the very first character to make a crossover into another fictional universe, in this case meeting the Golden Age Flash, Jay Garrick. He did it by way of a device they referred to as a Cosmic Treadmill - a handy little device that cameos in Injustice's story mode.
Green Arrow: Was reanimated by Parallax (Hal Jordan) as his last act before leaving Earth to reignite the sun. However, the Oliver Queen that Parallax resurrected was a soulless shell who'd forgotten much of the latter part of his life, and it wasn't until Oliver Queen's soul - residing in heaven - decided to come back and reinhabit his mortal form that Oliver Queen truly came back to life.
Green Lantern: Hal Jordan is a fighter pilot when not doing his Lantern thing. He refuses to fly while wearing his power ring, saying it takes all the risk and therefore the fun out of flying. Spent months in a nondescript Middle Eastern jail cell due to a crash landing in hostile territory, without his ring.
Harley Quinn: Has an immunity to most poisons, due to her association with Poison Ivy. It was a gift from Ivy, although exactly why Ivy did this is always slightly questionable. They've been implied - especially in alternate reality stories, where it's sometimes outright confirmed - to be in an on-again, off-again relationship.
Hawkgirl: Is a ressurrected Egyptian priestess or queen or something, from an alien planet. Said alien planet originally empowered the Egyptian priestess or queen or whatever, by giving her magical metal, or something like that. You know what? Fuck the Hawkman mythos.
Joker: Has no actual origin story. He's had suggested origins, but there's no confirmation - even within those stories - that any of it is true. Joker may not even know his own background or remember it with any sense of clarity or continuity, and if he does, he isn't telling.
Killer Frost: Was completely unimportant and unknown until they put her in the Young Justice cartoon. Shocking.
Lex Luthor: Almost entirely driven by his desire to assert his superiority over Superman. Lex's core belief is that humans are the greatest goddamn thing in the universe (and he's among the best of them), and Superman's existence as a complete alien with godlike powers causes him to become rather intensely and violently neurotic. Remove Superman from the equation, and Lex becomes a brilliant, benevolent philanthropist, scholar and political reformer.
Lobo: Is a giant joke on the Dark Age of comic books, much like Deadpool. The man who originally created him admitted with some confusion that he had no idea why Lobo became popular at all, much less how explosively so.
Martian Manhunter: Once turned into a hundred foot tall supervillain called Fernus the Burning. Yup.
Nightwing: Was raped by an insane supervillain who was trying to be a hero, also after having just killed one of NW's long-time nemeses. He was in a delusional state at the time, under the weight of serious exhaustion and extensive physical injury.
Raven: Always depicted in the comics as having the top half of her face cloaked in darkness if her hood is up, regardless of the direction lights are shining at her from or how bright they are. When she takes her hood off, her face becomes plainly visible and appears normal. One of the few things the Teen Titans cartoon ever got right.
Scorpion: Isn't a DC character! I hope you knew that.
Shazam: Was a crucial part of one of the most well-known DC alternate continuity stories of all time (Kingdom Come). Billy Batson was ultimately put in the position of deciding whether human or superhuman life was more important. He apparently felt it was somewhere in the middle.
Sinestro: Originally a Green Lantern. His sector was one of the most orderly in the galaxy, but he was stripped of his power ring when the Guardians of the Universe discovered Sinestro had achieved it through brutal tyranny. Even as a villain, he expresses a belief in adherence to law, but believes the best way to compel "correct" behavior is through fear and violence.
Solomon Grundy: Was born on a Monday. No, really. Somehow after falling in a swamp and coming out as a monster, the day of the week he was born on was the one single fact he could remember about himself.
Superman: Once had a Silver Age story where tiny duplicates of himself flew out of each of his hands, and could do everything he could do but better. It made him have an existential crisis about his role in the world and his usefulness in that role.
Wonder Woman: Has absolutely no issue murdering the crap out of bad guys when it seems logical, and doesn't get why everyone else gives her shit over it. She mostly plays by the rules guys like Batman and Superman set out, but doesn't remotely understand them.
Zatanna: Actually the offspring of a now virtually forgotten Golden Age hero, Zatara. A lot of people are to some degree familiar with Zatara as a backup character, it's less common knowledge that he actually had his own book back then, and was not always just in a supporting role. Her dad is one of the few comic book characters that's ever died and stayed that way.
Zod: Was originally introduced in the Silver Age as a nemesis for Superboy rather than Superman, in the era when Superman was thought to have taken up the tights as a teenager rather than after he'd moved to Metropolis as an adult. He was promptly bodied by a teenaged boy and sent packing.
That enough facts for you?
yeah... but really it's the writer's fault for saying that.
