20. Heather Graham
As Rollergirl, Graham gave one of several iconic performances in Boogie Nights. It's a deceptively complex role: She's seen as a fun-loving, ready-to-get-naked-at-a-moment's-notice sex object in the film's earlier scenes. As the story proceeds, however, the porn star on wheels becomes an increasingly sadder figure: The scene where she and Julianne Moore's Amber Waves sit in a bedroom doing lines of coke and becoming increasingly more agitated is one for the ages. ("Are you my mom? I'll ask you if you're my mom, and you say 'Yes,' okay?") And later, when she brutalizes a college student who tries to get rough with her in the back of a limo, we see an entirely new side of the character. Not surprisingly, this movie helped make Graham a star.