Monster

With her starring role in “Monster,” as Aileen Wuornos, a prostitute sentenced to death for killing six men in Florida, Charlize Theron shatters her glamour-girl image with one of the year’s most intense performances.

With the help of makeup artist Tony G, Theron is completely transformed from blonde beauty to angry, puffy, sun-spotted, stringy-haired street hustler.

“She wasn’t a subtle character,” admits Theron, who watched hours of documentary footage of the brash Wuornos. “She confronts everything with her body. And because of that, it gives you more of an opportunity to mask yourself.”

However, it was Theron’s similarly forceful presence that made her perfect for the role, according to “Monster” writer-director Patty Jenkins.

“She’s like a stallion, a beautiful creature, but you don’t want to piss her off, because she’ll cut you down to size,” she says. “But if you’re on her good side, she has this tremendous heart.”

Theron also provides a deeply fragile side to a woman known as the first female serial killer. “I used a lot of substitution from my own life and made it personal,” she says.

In the film’s most powerful display of Theron’s talents, Wuornos breaks down at a bus depot in a fit of devastating sobs. “Something happened to me. I can’t explain it,” admits Theron. “Afterwards, I ended up sitting in an alley for two hours and not being able to compose myself.”

While the part took an emotional and physical toll on the actress, she doesn’t feel “brave,” as she’s been called. “I thought actors were waiting, hungry and dying, to do these kinds of parts. I truly feel that I hit the jackpot.”

Indeed, Theron’s tour-de-force performance may change her career forever. “My greatest hope is that this movie will reopen directors’ and producers‘ eyes to see me not just as this one-dimensional thing,” she says.

While her next picture, John Duigan’s 1930s romantic drama “Head in the Clouds,” may be more of the same-old for Theron, that shouldn’t last for long. “My career has been a constant, ‘She’s too beautiful for the part,’ ” she says. “But I know that I’m capable of transforming. I’m fearless, I’m not an insecure artist, and I welcome any challenge.”

Coming attractions: “Head in the Clouds,” “The Life and Death of Peter Sellers”

Follow @Variety on Twitter for breaking news, reviews and more