Welsh actor Christian Bale is known as much for his amazing acting ability as he is for the lengths he'll go to for a part. He famously lost more than 60 pounds for his role in The Machinist, and convincingly played a serial killer in American Psycho.
To play Batman, Bale bulked up from 130 to 230, putting on a ton of muscle to play the Caped Crusader before turning to the jungles of Vietnam to play Dieter Dengler in Rescue Dawn. Wherever his work finds him, Bale's Aquarian mental preparation helps him get deep inside his character's skin.