Exactly How Justin Bieber Keeps His Baby Face So Smooth

What do Mick Jagger, John Mayer, Zac Efron, and Justin Bieber all have in common? Besides a set of pipes and a combined net worth high enough to fill Oprah Winfrey's 56-acre California estate with all the puppies and bath tubs, they also happen to be super beauty fans.

And there's a lot more where that came from. In fact, there's a whole list of unsuspecting actors, musicians, and Hollywood stars who are also low-key skin-care aficionados. Curious yet? Click through the slides ahead to find out exactly who they are, what they love, and why in the hell they haven't landed a beauty contract... yet.