So I'm working on a few ideas, but until I decide I'm interested in these again, these ideas will go here.
Quincy Sharp is the head of Arkham Asylum and eventually the Mayor of Gotham City. However, he's secretly insane and believes himself to be the spirit of Arkham.
Leslie Thompkins is a trusted ally of Matthew as she aids him in his medical needs.
Alfred Jarvis is the legal guardian of Matthew and his closest ally.
Commissoner Jim Stacy is one of the Batman's closest allies in the police.
Thomas Wayne, the father of Matthew Wayne. He was murdered by Joe Chill when Matthew was really young.
Martha Wayne is the mother of Matthew Wayne who was killed with her husband Thomas.
Maggie Sawyer is a detective and Kate Kane's girlfriend.
John Diggle is Oliver Queen's Bodyguard and best friend.
Yao Fei is the archer who taught Oliver everything he knew.
Amanda Waller, director of the Suicide Squad.
Lyla Michaels, John Diggle's wife.
Felicity Smoak is the brains of the Outsiders.
Joe Chill, the murderer of the Waynes
Copperhead is currently an unidentified female assassin.
Deacon Blackfire is a cult leader who claims to be an immortal native american shaman.
Floyd Lawton is a master assassin codenamed Deadshot. He deals with his desire to die gloriously, his desire for remembering those he killed, and his desire to give his daughter a good life.
Victor Fries was attempting to save his wife's life when he was turned into Mister Freeze.
Harleen Quinzel is the therapist assigned to study the Joker. But after being seduced by him, she becomes his henchman Harley Quinn.
Harvey Dent's war on crime lead to him becoming disfigured during a hostage crisis. This lead to him becoming the violent Two-Face.
Jonathan Crane's obsession with fear lead to him becoming an outcast. So to feed his arrogance, he became the Scarecrow to let others live in fear.
Bane is a fighter, hitman, drug addict, crime boss, and the man who will break the bat.
Slade Wilson is a superhuman mercenary constantly at odds with Batman known as Deathstroke.
Prometheus, the end of Justice.
Oswald Cobblepot lost everything as a child after his family wasted away the family wealth. When his father commited suicide and his mother went insane and sent to Arkham Asylum, he came to blame the Wayne family. He is now the Penguin.
Pamela Isley is the ecoterrorist known as Poison Ivy.
Hugo Strange is a mad scientist obsessed with Batman.
Edward Nygma is the Riddler, the man obsessed with proving he's superior to Batman.
Ra's Al Ghul is the immortal leader of the League of Assassins.
Talia Al Ghul, the daughter of Ra's and a lover of Batman.
Nyssa Al Ghul is the youngest daughter of Ra's Al Ghul.
Weylon Jones is the psychotic Killer Croc.
Selina Kyle is a morally dubious thief and vigilante called Catwoman. She's a lover of Batman.
The Schizophrenic Lazlo Valentin is Professor Pyg
Isabel Rochev had an affair with Robert Queen to get into a high ranking position within his company. When his son Oliver returned to take over the company, she took a dangerous dose of Mirakuru, the same drug that gave Deathstroke his powers, and became the Ravager.
Lonnie Machin, the living Anarky!
Evelyn Sharp is the former hero Artemis, until she betrayed the heroes.
Damien Darhk is a rogue immortal and leader of HIVE.
Jared Wendell Hamill is the source personality of the Joker. He keeps the other personalities in check, allowing a sort of neutrality among the others. Through blood transfusion and hypnotherapy, this personality is transferred to Thomas Elliot, Bruce's long lost brother.
Johnny Charisma is the most boisterous personality of the Joker, with severe Megalomania. When the Joker used hypnotherapy and blood transfusions on Jonathan Browne, he became possessed by Johnny Charisma.
Skullface is a personality created by the Joker to personify the belief that he was in the military before he became the clown prince. Because of that, he is cold and calculating, and a master strategist who doesn't hide behind the Facade of a clown. Through hypnotherapy and blood transfusions, the Joker managed to transfer this personality into James Ledger, becoming Skullface
Noface is a faceless personality of the Joker that defends it's existence by symbolizing the masks people wear to disguise their secrets. Through blood transfusions and hypnotherapy, the Joker managed to make this personality possess Alan Snyder.
Christina Bell represents (Of all things) the femininity of the Joker, and his bond with the Batman. Trough hypnotherapy and a blood transfusion, this personality is transferred to Bianca Steeplechase.
Albert King is a personality of the Joker of pure violence. Through a blood transfusion and hypnotherapy, this personality was transferred to Mark Desmond.
Henry Adams is the smartest personality of the Joker. He's the only one of the personalities willing to remove the make up and live an obscure lifestyle when necessary. He's intelligent enough to make well thought and thorough plans. Through Hypnotherapy and a Blood Transfusion, this personality was transferred to Jervis Wesker
Jack Napier is the original personality of the Joker. The most human of them all, he was destroyed by the Beast once all the other personalities were transferred to other hosts.
By far the most dangerous, hostile and terrifying of all the personalities, the Beast is an identity that resides in the Joker's mind. The Beast is extremely violent to the point of savagery, and an intense perspective that the world is just a massive joke over how humanity fights for a sense of normalcy and it's all pointless and that everyone should accept Chaos like he has. The Beast is viewed as an almost Godlike figure by the other identities. After transferring the other personalities into different hosts, the Beast dominates the entirety of the Joker's body, thus becoming one and the same.