2. Karen Gillian
To become Nebula in the movie Guardians of the Galaxy Vol. 2, Gillian sat through four hours and 15-minutes of makeup every day of filming. She had to shave her head for the role and wear 22-millimeter [read: huge] contact lenses. On top of all that, her character wore a skintight costume, so she also had to train in the gym and eat like an athlete to get in shape for the role. For a woman who doesn’t normally workout, hitting the weights four times a week was a big change. When she wasn’t in the gym working out, producers had her learning martial arts for fighting sequences.