We all know the story of Heath Ledger‘s Joker: How the talented actor pushed himself to the limits to try and emulate the perfect villain, locking himself in a London hotel room for a month, scribbling maddened non-sequiturs and manic comic strips, worsening his already destabilising insomnia. We all know the story of the man who lost himself to the role, who, months after filming for The Dark Knight had finished, was found dead in his New York …