Actor Heath Ledger, who passed away in 2008, kept a diary while preparing to portray the Joker in ‘The Dark Knight’, a role he posthumously won an Oscar for. Ledger’s father, Kim, was the one to reveal the diary in ‘Too Young To Die’, a German documentary movie about the actor. In the diary Ledger kept all kinds of things that he assumed the Joker would find funny and that would help himself get into character such as clowns, hyenas and photographs of Alex, the character in the Stanley Kubrick’s version of ‘A Clockwork Orange’.
While preparing himself for the part, Ledger spent about a month locked away in a hotel room in London experimenting with different voices and laughs. In an interview he later gave, Ledger said he managed to land in the realm of a total sociopath, cold-blooded and capable of mass murders.