When an actress takes on a new role, she has to totally transform into the character she's playing! While wigs, special effects, and expert hair and makeup teams can help a star quite literally morph into a totally different person for the sake of a film or TV spot, sometimes there's nothing more convincing than a star shaving her head, going big with a bold haircut, or dying her hair a vibrant rainbow shade.
Click through the gallery above to see which stars have dramatically changed up their hairstyles for a role. Which star's makeover surprised you the most? Share your thoughts below!