Often, celebrities will go to great lengths to channel the character they're playing in a movie. For example, to play her hilarious role as a sexually aggressive dentist in Horrible Bosses, Jennifer Aniston reportedly disagreed with studio executives over her hair color. "I'm the one who insisted on the dark hair," she recently explained, adding, "There was just no way I could be saying those words and not look somewhat different."
She got her wish and filmed the movie wearing a brunette wig, complete with bangs. Like Jennifer, other actresses have drastically changed their hair to get more into character. See 10 other stars who have undergone similar hair transformations for their craft now.