Transformation

Rachel McAdams is everyone's favorite girl crush. She stars in obsessed-over flicks like The Notebook and Mean Girls, she dates the coolest guys in Hollywood (Ryan Gosling, Josh Lucas, Michael Sheen, anyone?) and she's always doing something new with her hair. "It's a compulsion," she has said. "I'm always changing parts of me." From her natural blond hue to red locks to darkest brunette, McAdams doesn't fear the dye pot—or the drink packet. "Even when I was young, I wanted to change my hair color," she has said. "I was so determined that I dyed my hair with Kool-Aid." So when she hits the red carpet for her next premiere, don't be surprised if you spot some major changes. As she said of her Kool-Aid days: "Not that pretty, but it is still transforming."

The emerging star (and her girlish ponytail) made the scene with the release of The Notebook and Mean Girls.