The Elizabeth Arkham Asylum for the Criminally Insane, or simply Arkham Asylum, is a psychiatric hospital located in the outskirts of Gotham City. It was founded by Amadeus Arkham in the early 20th century, transforming it from a family estate in to a treatment center.
It is dedicated to rehabilitating those considered too dangerous for normal prisons such as Blackgate Penitentiary.
The Joker's Riot
At some point, after being captured by Batman, the Joker was imprisoned in Arkham, where he would eventually become the patient of the then Dr. Harleen Quinzel. The psychopath would successfully manipulate her into supposedly falling in love with him, and then had her give him a machine gun, thereby allowing Joker to start a riot.
Around the same time, his Joker gang overran the asylum, killing the guards and freeing him, leaving the facility in disorder while at it.
Lex Luthor's Imprisonment
Arkham was later restored from the damage caused by the Joker's riot sometime prior to 2016.
After Lex Luthor was found guilty of committing mass murder (in both Nairomi and Washington DC) as well as the framing and death of Superman, he was found to be mentally unfit to stand trial for his unspeakable crimes and was sent to Belle Reve supermax to await his final sentence.
Batman, furious that Lex had manipulated him into almost killing Superman (and had still gotten Superman killed despite that), and wanting to keep a close eye on the criminal supergenius, took the law into his own hands and had him transferred to Arkham Asylum where he could make sure the mastermind wouldn't cause any more trouble.
After he spent a year imprisoned within, Lex learned of the Justice League's formation and of the resurrection of Superman, and hence decided that it was finally time to enact his breakout plan. Having successfully done so without anyone noticing, Lex met up with Deathstroke.
- Amadeus Arkham – founder
- Dr. Harleen Quinzel – psychiatrist
Originally, Arkham Asylum was used only to house genuinely mentally ill patients, having no connection to Batman or his allies, but in more recent years, it has became infamous for holding the majority of the Dark Knight's adversaries, with almost every one of them ending up within Arkham at least once.
- Babrius Aesop – A Gotham City-based criminal who used the moral lessons found in Aeosop's Fables as his MO.
- Joker – An immensely formidable criminal psychopath, top crime boss of Gotham City's criminal underworld, imprisoned by Batman for committing numerous crimes, later released in a breakout organized by Joker's gang.
- Harley Quinn – Once a psychiatrist at the Asylum, Dr. Harleen Quinzel would later become a patient at the institution herself, imprisoned by Batman for her numerous crimes, later transferred to Belle Reve.
- Killer Croc – Formidable villainous metahuman, imprisoned for his many crimes in Gotham City, most notably cannibalism. He was transferred to Belle Reve.
- Lex Luthor – An immensely formidable supergenius psychopath, formerly imprisoned for committing unspeakable crimes against peace and humanity, orchestrating the Nairomi Incident and the US Capitol bombing (killing numerous people in both instances), as well as unleashing Doomsday, a monster that killed Superman and nearly brought about a global apocalypse. Lex is transferred to Arkham from Belle Reve supermax through the influence of Batman, since Lex had been declared insane, and therefore and unfit for trial. Following Steppenwolf's defeat by the Justice League, Lex manages to break out of Arkham, so as to meet up with Deathstroke.