When it comes to talent, these celebrities are triple threats. While stars like Sarah Jessica Parker and Meryl Streep are known for their groundbreaking TV and movie roles, you'd be surprised to know that they got their start singing and dancing on the stage. In fact, many of them still raise their incredible voices from time to time (looking at you, Anna Kendrick). Whether or not you're a theater nerd, you'll definitely appreciate some of these stars' humble beginnings on Broadway.