I had read an interview somewhere where Heath Ledger said he went to Jack Nicholson for advice on the Joker role, in that meeting Nicholson said that the best advice he could give him was not to get eaten by the role, that it was a powerful character and he could easily fall into its trap and get stuck in it, just like, supposedly, Jack himself almost did. Now, if anyone believes that that was what consumed and eventually killed Ledger is very much up for debate, but there's no denying that ledger was REALLY into his character.
Prior to production, Ledger locked himself in his hotel room for a month preparing for the role. During this stint of almost six weeks he wrote in a journal and practiced different voices for his character. In this creepy Journal, written during his time of isolation, there were in-character ramblings and inspirations. He also included photographs of hyenas, clown make-up designs, joker cards and even stills from A Clockwork Orange, which is a movie Nolan recommended Ledger watch to prepare for the Joker. Some of the writing contained in the journal was from the perspective of the Joker, including a list of suspicious things he thought were funny like AIDS, blind babies, landmines and smart people that suffer from brain damage (don't ask). On the cover, the words THE JOKER, with the picture of an elephant and a man on a checkered floor. The last page of the journal had the words “BYE BYE” handwritten in large letters.
Back in 2008 I wrote this about the movie and Ledger's performance:
"If you haven't heard of Christopher Nolan's soon-to-be classic "The Dark Knight" then you don't live on this planet or are completely oblivious to what's going on in pop culture. Nolan along with an A-list cast headlined by Christian Bale as Batman and the late Heath Ledger as the Joker make sure to to haunt your dreams with this movie. Many have evoked the film as a post-9/11 depiction of a world gone to hell. They might not be far off. Bale's caped crusader needs to lower himself to the depths of evil in order to make good triumph. As for Ledger's Joker, he feels so real and intense that you feel uncomfortable whenever he appears on-screen. It's one of the great movie performances of our time."
Here are 15 rare pictures of Ledger on the set of "The Dark Knight."
[Den of Geek]