Turning 13 years old is a big deal. After all, it's when you officially become a teenager. That's a huge milestone! Obviously, we have 13 on the brain because it's Sophia Grace's birthday!

You probably know her as the little girl who first broke onto the scene as an eight-year-old rapping to Nicki Minaj's "Super Bass," but now she's officially a teenager, and all grown up. (Yeah, we know. It's feels like everything happened so fast.) Can you believe it?

She's not the only star you've watched grow up in the blink of an eye. There are tons of celebrities who you may never have guessed are actually 13 years old.

Click through the gallery to see other stars you won't believe are actually 13 years old. Let us know if it shocked you in the comments!

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