2. Christian Bale
No, Christian Bale didn't spend months running around Chicago in a black cape and growling prior to working on the Batman films. Bale's method acting antics reportedly began on his breakout role, American Psycho, whereby he would, like his character Patrick Bateman, spend hours in the gym each day and refuse to talk to anyone on set. However, his method took a much crazier turn when he played Trevor Reznik in The Machinist, losing 4-and-a-half stone by eating just an apple and a can of tuna a day, as well as smoking like a chimney. The results are impressive and frightening all at once; Bale looks resolutely unhealthy (duh), and apparently wanted to lose even more weight, but the producers sternly warned him against it out of fear for his life. As soon as shooting wrapped, Bale then had to gain over 60 pounds in order to play the muscular Bruce Wayne for Christopher Nolan's Batman Begins. No rest for the wicked? Bale's on-set hissy fit at cinematographer Shane Hurlbut on the set of Terminator Salvation was a shock to us all, and an instance of an actor being held in the Method seemingly against his will. Bale kept himself in the head space of John Connor for the entire shoot, and so sounding off at a crew member who made a mistake was an unfortunate extension of that. For better and for worse, Bale is one of the most intense and scarily devoted method actors out there. But not quite the most...