Bonnie McKee

We already know this girl can sing -- "American Girl" -- but many people don't realize that Bonnie McKee has been extremely present in the music for years. In fact, she has numerous hits, but she never sang them herself.

Bonnie wrote a majority of Katy Perry's #1 songs, including "Roar" and "Teenage Dream".

This video features Bonnie singing a medley of her hit songs. I guarantee you will know each and every one of them, but hearing them by their original author makes them that much greater and makes this medley worth a listen.