3. Charlize Theron (Monster)
The 2003 crime biographical drama film starred 39 year old South African-American actressCharlize Theron in the role of Aileen Wuornos, a person who was executed in Florida in 2002 for killing six men. Theron gained 30 pounds and had to wear prosthetic teeth for the role, resulting in her becoming absolutely unrecognizable. Her effort paid off, as she vowed the audience and critics with her transformation and even won the Oscar for Best Actress in a Leading Role for the movie.