Charlize Theron in Monster
Charlize Theron is another actress who changed her appearance completely in order to make her role as believable and realistic as possible. Depicting the role of serial killer Aileen Wuornos, the actress got a complete makeover during the filming of Monster.
Her skin was layered with tattoo ink to make it match that of the real Wuornos, she wore dentures, her hair was thinned and repeatedly fried, and she shaved her eyebrows. By the end of the whole process, the beautiful actress was in no way recognizable.