It's always a bit of a shocker to hear what some actors are willing to endure in the name of "authentic performances," whether it's chopping off all their hair, sitting in a makeup chair for hours on end, or, in extreme cases, submitting to unorthodox dieting habits.
Movie transformations have recently come back to the forefront in light of films like 'Les Miserables,' 'Cloud Atlas' and 'Looper.' While Anne Hathaway and Hugh Jackman have both admitted to extreme dieting habits to convey the physical embodiment of death, others, like Tom Hanks and Joseph Gordon-Levitt, have succumbed to hours upon hours of costume and makeup work.
Despite some of the un-glamorous techniques, these movie transformations have astounded audiences all over the world and earned some of the performers the highest of honors. Here's a look back at 13 mind-blowing actor transformations in film.