The Joker (Heath Ledger)

"This town deserves a better class of criminal...and I'm gonna give it to them!"

- The Joker

The Dark Knight Time Frame
At the beginning of the movie, a bank is robbed by a gang of brazen, clown-mask wearing thieves, who within minutes whittle down their own number until only the Joker, who had planned the double-cross, remains. He escapes with the entire amount stolen from the bank, which served as a money-laundering front for Gotham's gangs.

After that, The Joker arrives unannounced at the meeting and offers his services to kill Batman for "half" of all the money that was taken away from Gotham. Eventually, realizing that Batman has retrieved the Chinese mobster from Hong Kong and that police have struck a deal with to testify against them, they relent, finally hiring the Joker to kill the Batman. Dent has over five hundred of them arrested in one day due to the Hong Kong mobster's confession. Joker tells all of Gotham that if the Batman doesn't unmask and turn himself in he will kill innocent people every day. As a result of the Batman not turning himself in, the first major victims are the judge presiding over Dent's indictments and the police commissioner. The Joker's attempt to kill Dent at a Wayne fund raiser fails. Lieutenant James Gordon, however, is killed saving the mayor of Gotham by the Joker himself at a memorial for the murdered police commissioner. As a result of this, Batman tells Dent to call a press conference so can reveal his identity and stop the killings. In a surprise move, Dent instead claims to be the Batman himself and is subsequently arrested. While being transported the Joker and his gang attack the caravan of police vehicles to kill Dent, but Batman arrives and stops the assault, but stays his hand at killing the Joker. The Joker prepares to kill Batman but Gordon - revealed to have faked his death - steps out and pistol-whips the Joker unconscious, and is promoted to Commissioner by the mayor. With the Joker in custody Gordon and Batman interrogate the Joker when he reveals that he and the mob have taken Rachel and Dent to opposite sides of the city and one will die. Batman beats the location of the two from the Joker and speeds off to save Rachel while Gordon and the police are off to save Dent. Dent and Rachel each awaken, tied to chairs with barrels of explosive material surrounding them and a speaker phone hooked up to the other's location. Rachel confesses her love for him and agrees to marry him. Harvey falls on the floor and his left side is completley immersed in turpentine. Batman arrives but finds Dent instead of Rachel. He realizes that the Joker had lied about Rachel and Dent's whereabouts. Batman rescues Dent as the building explodes and Harvey's face is badly burned, while Gordon is unable to rescue Rachel before the explosion. In the hospital Harvey is driven to madness over the loss of Rachel, and blames Batman, Gordon and the Joker.

When one of Wayne Corps employees threatens to go public on the news with information about Batman's identity, he is interrupted by the Joker who states that if someone doesn't kill the employee in sixty minutes he will blow up a hospital. While the new commissioner is evacuating the hospitals, the Joker, poorly disguised as a nurse (he is still wearing his 'Joker' facepaint), enters the hospital room of Harvey Dent. Blaming the mob and Gordon's corrupt cops for the kidnapping and murder of Rachel, he convinces Harvey to exact his revenge upon them. After Dent leaves, Joker detonates the Gotham General Hospital, skipping merrily away.

While Harvey confronts one of the corrupt cops, the Joker declares that he will rule the streets and that anyone left in Gotham will be subject to his rule. He tells people they can leave now but that he'll have a surprise for them in the tunnel and on the bridge, which people then avoid, using instead two ferries, one ship full of criminals and one of ordinary civilians. However, the Joker has loaded each of them with explosives. In hopes of showing everyone how evil and corrupt they can be he gives the passengers of one ship the detonator to the bombs to the other. If they don't choose by midnight, the Joker will blow up both ships. The civilians vote to blow up the other ferry, but cannot bring themselves to actually do so, while one of the criminals steps forward and, taking the detonator, throws it out a porthole saying that the cops should have done that from the start.

Batman discovers not only the Joker's location at an unfinished skyscraper, but that the majority of his "gang" are hostages wearing clown-masks with unloaded guns taped to their hands and that the people dressed at hostages are the actual criminals. Batman is forced to fight not only the Joker's men but the SWAT teams as well to save the hostages. He finally confronts the Joker, preventing him from blowing up the two ferries and then saving him from falling to his death. The Joker acknowledges that Batman really is indeed incorruptible but that Dent is no longer the white knight; he's unleashed the scarred man on the city. Joker states that Dent was his "ace in the hole" in his plan to show the people of Gotham that everyone is corruptable, thus undoing Dent's work before his transformation into Two-Face. Batman leaves the Joker to dangle helplessly as he is approached by the SWAT team, who most likely cut him loose and apprehend him. All the while the Joker laughs menacingly.

Behind the Scenes
Heath Ledger as The Joker: Heath Ledger described the Joker as a "psychopathic, mass murdering, schizophrenic clown with zero empathy". Nolan had wanted to work with Ledger on a number of projects in the past, but had been unable to do so. When Ledger saw Batman Begins, he realized a way to make the character work consistent with that film's tone, and Nolan agreed with his anarchic interpretation. To prepare for the role, Ledger lived alone in a hotel room for a month, formulating the character's posture, voice and psychology, and kept a diary, in which he recorded the Joker's thoughts and feelings to guide himself during his performance. While he initially found it difficult, Ledger was eventually able to generate a voice that did not sound like Jack Nicholson's take on the character in Tim Burton's 1989 Batman film. He was also given Batman: The Killing Joke and Arkham Asylum: A Serious House on Serious Earth to read, which he "really tried to read [...] and put it down". Ledger also cited inspirations such as A Clockwork Orange and Sid Vicious, which were "a very early starting point for Christian [Bale] and I. But we kind of flew far away from that pretty quickly and into another world altogether." "There’s a bit of everything in him. There’s nothing that consistent," Ledger said, adding that "There are a few more surprises to him." Before Ledger was confirmed to play the Joker in July 2006, Paul Bettany, Lachy Hulme, Adrien Brody, Steve Carell, and Robin Williams publicly expressed interest in the role. On not being invited to reprise the Joker, Jack Nicholson remarked that he was "furious". In turn, responding to his initially-controversial selection to play the Joker, Ledger stated publicly, "It would not matter who is chosen to play the [Joker]. [...] In any film, there is always someone who does not like you and I am secure in my choices and my record. But I know at the end of the day you are never going to please anyone 100 percent…I refuse to carbon copy a performance. That would not be a challenge and it would be mocking Mr. Nicholson, whom I have much respect for."

On January 22, 2008, after he had completed filming The Dark Knight, Ledger died, leading to intense press attention and memorial tributes. In March 2008, four months prior to the film's scheduled release, Larry Carroll reported that "like Batman himself, Christian Bale, Maggie Gyllenhaal and director Christopher Nolan find themselves shifting gears between being secretive, superheroic and fighting back a deep sadness." "It was tremendously emotional, right when he passed, having to go back in and look at him every day," Nolan recalled. "But the truth is, I feel very lucky to have something productive to do, to have a performance that he was very, very proud of, and that he had entrusted to me to finish." All of Ledger's scenes appear as he completed them in the filming; in editing the film, Nolan added no "digital effects" to alter Ledger's actual performance posthumously. Nolan has dedicated the film in part to Ledger's memory, as well as to the memory of technician Conway Wickliffe, who was killed during a car accident while preparing one of the film's stunts.

Design
The Joker's scruffy and grungy make-up is intended as a reflection of his "edgy" character.Costume designer Lindy Hemming described the Joker's look as reflecting his personality—that "he doesn't care about himself at all"; she avoided designing him as a vagrant but still made him appear to be "scruffier, grungier", so that "when you see him move, he's slightly twitchier or edgy." Nolan noted, "We gave a Francis Bacon spin to [his face]. This corruption, this decay in the texture of the look itself. It's grubby. You can almost imagine what he smells like." In creating the "anarchical" look of the Joker, Hemming drew inspiration from such countercultural pop culture artists as Pete Doherty, Iggy Pop, and Johnny Rotten. During the course of the film, the Joker only once removes his make-up, causing it to become more unkempt and resemble an infection as it worsens. Ledger described his "clown" mask, made up of three pieces of stamped silicone, as a "new technology", taking much less time for the make-up artists to apply than more-conventional prosthetics usually requires—the process took them only an hour—and resulting in Ledger's impression that he was barely wearing any make-up at all.