9. Heath Ledger - The Dark Knight

It really is hard to believe, but when Christopher Nolan announced he had cast Heath Ledger in the Joker role for The Dark Knight, fan boys were up in arms. Known prior to it for playing pretty boy roles (a Knights Tale, 10 Things I hate About You) and the tortured souls (Brokeback Mountain, Monsters Ball), offering him the role of the Clown Prince couldn't have been more off the mark. Or at least, so the world initially thought. Heath Ledger locked himself in a hotel room, isolated himself from the outside world (including his own family) took prescription drugs by the bucket load and descended into a complete personal hell in order to really encapsulate the anarchy that comes with playing The Joker. Ledger told reporters he "slept an average of two hours a night" while playing "a psychopathic, mass-murdering, schizophrenic clown with zero empathy. I couldn't stop thinking. My body was exhausted, and my mind was still going." Prescription drugs didn't help. he also added. After tragically dying from a combination of said prescription drugs and exhaustion, the former Joker, Jack Nicholson, infamously stated he knew the reason for his Ledgers demise. "Well, I warned him." - Cryptic and ill timed it may have been, but unfortunately for the world, it is a statement that wasn't too far from the truth about the dangers of actors losing themselves in the dark world of method acting.