As teen vampire slayer Buffy Summers, Sarah Michelle Gellar made an iconic accessory out of a cross necklace. As wealthy, manipulative queen bee Kathryn Merteuil, she did it again — but this time, her rosary was full of cocaine.

There's something especially brilliant about the way Gellar toyed with her image in Cruel Intentions, which premiered on March 5, 1999, in the midst of Buffy the Vampire Slayer's third season. She was hardly the first TV star to play against type on the big screen, but her role in the soapy cult classic was even more fun because of the way it commented on her Buffy persona.

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Two-faced prep school student Kathryn pretends to be as sunny as Buffy actually is, but she's gritting her teeth every step of the way. Kathryn resents society for making women perform sweetness, and it's obvious Gellar, who dyed her signature blond hair brown for the film, is enjoying the chance to sink her teeth into the dark side of playing a good girl.

In honor of Cruel Intentions' 20th anniversary, we rounded up a list of 15 TV stars — including one of Gellar's co-stars in the movie — who showed off their range by shaking up their image on the big screen.

PHOTOS: TV Stars Who Played Against Type in Movies