You may remember Alyson Stoner from the Step Up movies, Cheaper by the Dozen or The Suite Life of Zack and Cody, but the little girl you're picturing has totally grown up. In fact, today's her 21st birthday! Pretty mind blowing, right?
Alyson's not the only star who seemed to grow up in the blink of an eye. Click through to see more celebrities who grew up way too fast for our liking, then let us know in the comments below who you think has grown up the most.