17. Punk Joker
From the first released images, it was clear that Heath Ledgers Joker was going to be just a
little bit different from Jack Nicholsons. Ledger and Nolan sought to bring a bit of a punk flavor to their Joker; their touchstones were
singer Sid Vicious, and Alex DeLarge from A Clockwork Orange, figures who they felt embodied societal fears about teen rebellion. To get in the right anarchic, "rude" mood for the character,
Ledger apparently kept a "Joker diary", in which he wrote down various things the Joker would find funny -- among them AIDs, land mines, geniuses suffering brain damage and sombreros.
A similar list appeared in the April 2007 issue #663 of the Batman monthly title, by Bat-genius Grant Morrison; either Ledger read the issue in question and felt that Morrison's list would help get him in character, or that's a really weird bit of coincidence.