The Joker (Batman: Assault on Arkham)

An insanely homicidal super-villain, the Joker's white skin, green hair, and ruby-red lips belie the chaotic nature underlying his colorful appearance.

Batman: Assault on Arkham
The Joker had somehow managed to steal a dirty bomb with enough destructive power to wipe out more than half of Gotham City's population with the Riddler's involvement, and hid it somewhere inside Gotham while imprisoned in Arkham Asylum. Because of this, Batman was tasked with finding the dirty bomb, which resulted in him directly interfering with a separate operation conducted by Amanda Waller against the Riddler, although he kept its location a secret even from the Riddler. His actions were also indirectly responsible for the Suicide Squad's initiation due to Batman's interference in Waller's operation.

Eventually, he discovered that his henchwoman, Harley Quinn, seemingly dumped him in favor of a new guy, although he soon discovered that her earlier assault on him was actually a subtle attempt at helping him escape. He then killed several guards, made an ambush on the Suicide Squad with explosive marbles, attempted to hold up whom he believed was Batman (eventually being impressed with the gun when Batman's head seemed to explode) and then made a transmission to Batman (shortly after he was exposed as having replaced Black Spider to the rest of the Suicide Squad) revealing that he intended to leak Titan throughout the city, and also released all of the Arkham Asylum inmates (Two-Face, Bane, Poison Ivy, Viktor Zsasz, etc., etc.) to hold Batman off, anticipating the likelihood that Batman would try to stop him.

He eventually, alongside Harley Quinn (who succumbed to her attraction to the Joker) managed to stow away on a helicopter that Deadshot managed to hijack, and got into a fight, eventually revealing that Harley Quinn's mallet contained the dirty bomb, resulting in Harley Quinn crashing into an under-construction building. Joker then confronted Deadshot, where the psychopath tried to kill his former hire in a toe-to-toe battle. He eventually managed to subdue him after knocking him into a glass panel, although with enough effort that he even admitted that he was "a real pain in [Joker's] ass" for someone who wasn't Batman. However, Deadshot managed to overpower him despite his wounded state, even trapping him inside the crashed helicopter and knocking it down to the street below, although he managed to laugh at his seemingly inevitable death. Batman managed to disarm the bomb after subduing Harley Quinn separately.

Despite being trapped in a helicopter crash, he managed to escape into the night.

Batman: Arkham Asylum
Two years later, Joker would instigate a similar riot at Arkham Asylum.