Charlize Theron is unrecognizable in her role as serial killer Aileen Wuornos in 2003’s Monster. She gained 30 pounds by eating potato chips and Krispy Crème donuts (but mostly potato chips), shaved off her eyebrows and wore prosthetic dentures and contact lenses. Her worn and blotchy skin was achieved by layering on washable tattoo ink. She went all out and it paid off. She won the Oscar for Best Actress for her role.