Leonardo DiCaprio @ 18...
Worked with Hollywood heavyweight Robert DeNiro on This Boy's Life, and costarred alongside Johnny Depp in What's Eating Gilbert Grape, for which he received his first Oscar nomination
Jessica Simpson @ 18...
Put the finishing touches on her debut album, Sweet Kisses, which included her first hit single, "I Wanna Love You Forever"
Tom Cruise @ 18...
Followed up a small role in Endless Love with an even bigger one in the military drama Taps, costarring fellow youngsters Timothy Hutton and Sean Penn
Katie Holmes @ 18...
Landed the part of tomboy Joey Potter on the hit teen series Dawson's Creek
Britney Spears @ 18...
Skyrocketed to instant fame with the smash "…Baby One More Time," off the album of the same name
Angelina Jolie @ 18...
Seen here with dad Jon Voight, kicked off her professional movie career playing a not-quite-human character in the sci-fi sequel Cyborg 2
Christian Bale @ 18...
Tried to revive the movie musical with Disney's Newsies
Justin Timberlake @ 18...
Became an immediate heartthrob with the success of 'N Sync's debut album and the boy band's hits like "Tearin' Up My Heart" and "I Want You Back"
Ashlee Simpson-Wentz @ 18...
Flexed both her acting and vocal muscles with a role on the feel-good family drama 7th Heaven and recording a song for the holiday album School's Out! Christmas
Christina Applegate @ 18...
Helped make Married With Children wildly popular thanks to her portrayal of bubbleheaded bleach blonde Kelly Bundy…and was rumored to be briefly linked to 26-year-old Brad Pitt!
Lindsay Lohan @ 18...
Won Best Breakthrough Performance at 2004 MTV Movie Awards for Freaky Friday and saw the release of two of her films, Confessions of a Teenage Drama Queen and Mean Girls, that same year
Mary-Kate & Ashley Olsen @ 18...
Shot the comedy New York Minute...while managing to squeeze in a little thing called graduation
Sarah Jessica Parker @ 18...
Was light years away from becoming a fashion icon during her Square Pegs days with costar Amy Linker
Cameron Diaz @ 18...
Graced the cover of Seventeen magazine and racked up frequent-flyer miles by way of modeling gigs around the world
Jennifer Aniston & Chastity Bono @ 18...
Were good friends at the High School of Performing Arts in New York. Who knew?
See more stars hustling for their big break Before They Were Fabulous!