77. Leighton Meester
Age (circa 2009): 23
Given the fact that she was born while her mother was in prison for participating in a weed smuggling ring, we have to say that (crappy duets with Cobra Starship notwithstanding) Leighton Meester has done pretty well for herself. After bouncing from TV show to TV show, she finally found a hit with Gossip Girl, where she consistently steals the show as the evil (and sexy) Blair Waldorf.
Playing a virginous pop star on Entourage.