2. Robert De Niro - Raging Bull (1980)
In Scorsese's classic film, DeNiro's Jake LaMotta fights in the ring and against himself, battling with demons of self-loathing and paranoia. DeNiro is spectacular in Raging Bull, channeling the real-life pugilist in a way that makes us believe the actor is truly a boxer. But when we see LaMotta outside of his prime, he's chubby, no longer the lean middleweight fighter LaMotta was known as being. DeNiro packed on around 70 pounds to play the less-fit version of the raging bull, resulting in the actor suffering from difficulties in posture and breathing. In the end it seemed worth it, winning DeNiro the Academy Award for Best Actor.