Most Infamous Moment: Two days before her 18th birthday in 2004, she checked into rehab for her battle with anorexia nervosa.

We literally watched Mary-Kate Olsen grow up from a Full House baby to a young billionaire. So it was a shock to start witnessing the pressure of Hollywood began catching up with her in 2004, when she appeared sickly thin during her Hollywood Walk of Fame ceremony. She's since sought help and made a full recovery. Now, she's dating the Olivier Sarkozy, the brother of former French president Nicolas Sarkozy who's twice her age (and height).