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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Fred Prouser/Reuters
If you see Renee Zellweger on the red carpet, you're likely to spot her slimmed down, as she's seen here before the 2002 Oscars.