Heath ledger the dark knight

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 [sic]. 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 January 22, 2008, after he had completed filming The Dark Knight, Ledger suddenly died, leading to intense press attention and memorial tributes. "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.