Afraid of monsters? Not Mary Gibbs. She grew up with them! Mary is the cutie-pie voice of brave little Boo in Monsters, Inc. The California kid first made recordings—mostly giggles and screams—for the film when she was only 2 years old. "It's just starting to sink in that she's in a movie," says her father, Rob. Mary, now 5, started kindergarten this year. She's excited about acting in school plays. Her dream role: a munchkin in The Wizard of Oz.