Arkham Asylum was a psychiatric hospital that appeared in the DC Animated Universe.
History[]
Batman: The Animated Series[]
Arkham has appeared frequently in the series. It is depicted as generally dark and gloomy, and the cells are similar to those in the comics, being primarily closed via glass doors. Much of the rest of the asylum resembles a prison more than a mental hospital, however; in one episode, it is explained that all criminals apprehended by the Batman are sent to Arkham rather than jail (although it is shown that Harley Quinn goes to Stonegate, a regular jail).
In the series, neither Jeremiah or Amadeus Arkham are shown or mentioned, but the episode "Dreams In Darkness" features a character who is obviously modeled on Jeremiah, but toned down to have a more compassionate persona. It's known inmates are Joker, Mr. Freeze, Two-Face, Scarecrow, Mad Hatter, Riddler, Killer Croc, The Penguin, The Ventriloquist & Scarface, Baby Doll, Maxie Zeus, and Lock-Up. The Asylum had a much more gothic and prison-like appearance in BTAS whereas it became more sterile as the DCAU went on.
Justice League[]
Justice League featured Arkham in a brief cameo during A Better World: Part 2 in an alternate dimension where a Fascist League has taken over the world and dispatches villains via execution or lobotomy. The asylum is run by a lobotomized version of The Joker and is protected by robotic copies of Superman. The entire patient population is lobotomized by the alternate Superman's heat vision. (If you watch closely, you can see that the Ventriloquist has not been lobotomized by Superman's heat vision, but his doll Scarface has.) It is noted that Joker, Two-Face and Mad Hatter are used in both Batman: The Animated Series and Justice League as the key patients of the Asylum.
Batman Beyond: Return of the Joker[]
This direct-to-video animated film had the final battle between the original Batman and The Joker taking place at an abandoned Arkham. It is also the same spot where Robin (as a brainwashed, junior version of The Joker) killed Joker. A deleted scene (featured on both versions of the DVD as a special feature) has Bruce Wayne touring the abandoned Arkham, where Terry McGinnis, Wayne's successor as The Dark Knight, follows and sees Joker's corpse hanging (it was implied that the new Joker placed it up there fairly recently to intimidate Bruce Wayne, or anyone investigating it, since it was bound by ropes, which the Joker's recent corpse wasn't, and more importantly, his corpse now bears the words "I know" on it.).