Most of the time being a Hollywood actor is all about the glitz and the glamour, but occasionally actors have to go that extra mile to transform themselves for a role. Take a look at some of the most dramatic actor transformations ever seen on film.
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Fox Searchlight Pictures
But Portman went even further, in a way, for her Oscar-winning role in 2010's "Black Swan." Months before director Darren Aronofsky's psychological drama went into production, Portman was dieting, working out and dancing to the extreme, all in an effort to get the tiny and frail, yet flexible and strong body ballerinas are known for.