- "We have hospitals who treat the mentally ill with compassion... but that's not where you're going. I've arranged for you to get a transfer to Arkham Asylum in Gotham. I still have some friends there. They're expecting you."
- —Batman to Lex Luthor
Arkham Asylum, commonly called Arkham, is a psychiatric hospital located on the outskirts of Gotham City. It is dedicated to rehabilitating those considered too dangerous for normal prisons such as Blackgate Penitentiary.
- Joker - a psychopathic criminal mastermind who was broken out by his gang
- Doctor Aesop - a Gotham City-based criminal who uses the moral lessons found in Aesop's Fables as his M.O.
- Alexander Luthor, Jr. - a psychotic businessman responsible for unleashing a chaotic giant monster and indirectly killing the alien hero, Superman
- Suicide Squad
- Suicide Squad (Novel)
- Batman v Superman: Dawn of Justice Crossfire (First appearance)
- Batman v Superman: Dawn of Justice (Mentioned only)
- Justice League
|Media||Batman v Superman: Dawn of Justice | The Batman|
|Characters||Batman/Bruce Wayne | Alfred Pennyworth | Thomas Wayne | Martha Wayne | James Gordon | Lucius Fox | Jason Todd | Clark Kent/Superman | Diana/Wonder Woman | Dick Grayson|
|Enemies||Joker | Harley Quinn | Killer Croc | Deadshot | Penguin | Lex Luthor | Deathstroke | Catwoman | Poison Ivy | Jonny Frost | Anatoli Knyazev | Joe Chill | Doctor Aesop | Firefly|
|Miscellaneous||Gotham City | Batcave | Arkham Asylum | Wayne Manor | Batmobile | Batsuits | Wayne Enterprises | Bat-Signal | Gotham City Police Department | Aragon Theatre | Batman film series | Ace Chemicals | Glasshouse | Batwing | Wayne Family | Blackgate Penitentiary | Batman Family|