Charlize Theron's tour de force in MONSTER is the performance of this decade, and perhaps any decade you'd care to mention.
In January 1991, aging prostitute Aileen Wuornos was arrested in Florida. She was suspected of killing seven men since 1989, leaving their bullet-riddled bodies near highways, and stealing their cars and cash. In January 1992, Wuornos was tried, convicted, and sentenced to death, mostly on the evidence of her own confessions and the testimony of her lesbian lover during the killing spree, Tyria Moore. In October 2002, the state took her life. MONSTER is Aileen's story.
Even a cursory reading of the Wuornos tragedy on the Web will indicate the challenge of Charlize's incredibly taxing role. It's not just the make-up (shaved eyebrows, false teeth), body alteration (thirty pounds added weight), and costumes that the actress put on for the role. It's the walk, talk, nervous mannerisms and body language. Even aura, if you believe in such. Theron is unrecognizable as herself. The transformation is apocalyptically stunning.
The film does, of course, take liberties. Tyria Moore, 24-years old when she met Wuornos in 1986, becomes "Selby" (Christina Ricci), who's about 18 in the script. The screenplay inferred to me a time span of perhaps several months for the Aileen-Selby relationship, and that the first killing occurred about when the two first met. In fact, Aileen and Tyria spent four years together, and the first murder was committed only towards the end. In any case, Ricci deserves consideration for an Oscar in a supporting role as the troubled, naive, and clueless Selby totally out of her depth.
At one point, Theron's Aileen states that she was raped by her father's friends, and that he subsequently beat her for it.