Neil Patrick HarrisDavid Burtka, Neil Patrick Harris Shia LabeoufShia LabeoufRyan Reynolds

Who would have ever guessed Louis Stevens, the troublemaker from "Even Stevens," would transform into one of the biggest on-screen heartthrobs? We have to hand it to the casting directors (especially the ones from the Harry Potter series), who were able to pick these guys out at such a young age. Take a look at 7 of the most unexpected on-screen hotties, who started off their acting careers with some not-so-dreamy roles.

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