1. CHARLIZE THERON

Movie: Monster (2003)
Watching Charlize Theron ugly herself up for crime thriller Monster was hard to stomach. She gained 30 pounds through a diet of junk good, wore prosthetic teeth and dabbed on dark makeup to obscure her clear and fresh complexion in order to portray serial killer and former prostitute Aileen Wuornos. The infamous transformation was justified with her Oscar win for Best Actress.