8. Christian Bale (The Machinist)
You all know the story here - Christian Bale takes two years out from looking buff after films like Equilibrium, American Psycho and Reign of Fire, only to make a comeback in a low-budget, shot in Spain (but set in California) flick about a scarily under weight industrial worker losing his mind through lack of sleep. Bale famously lost 63 pounds (that's 4.5 stone for us Limey Brits) for the role, by supposedly only having an apple and a cup of coffee a day. His look is not only hauntingly freakish, but also fragile. He looks as if he could break a bone just by walking, something that is so far removed from his rapid weight gain (again, 63 pounds) for Batman Begins a year later. An actor who pushes himself that far to the edge surely deserves to be on a list that is all about performances in the extreme, even if his real state did overshadow anything he did within his role.