1 of 10
Matthew Lewis (Neville Longbottom, Harry Potter)
Voldemort didn't think much of Neville Longbottom as a kid, but if the dark wizard could see Matthew Lewis now even he would swoon. The former Gryffindor now stars in the war comedy Bluestone 42.
2 of 10
Malcolm David Kelley (Walt, Lost)
If you watched Lost, you probably recognize this guy. Maybe TV dad Michael wouldn't have been so broken up about losing poor "WAAAALLLT!" if he knew how well he'd turn out: Kelley is one half of the pop duo MKTO and just released the single "Bad Girls."
3 of 10
This is Grace from The Nanny?
Who would've thought sweet little Grace would grow up to be such a bombshell? Since then Zima's had a slew of guest-starring roles and can next be seen in the movie Weepah War for Now (and Nick @ Nite reruns).
4 of 10
Ivana Baquero (Ofelia, Pan's Labyrinth)
The Spanish actress is best known for her quietly powerful turn as little Ofelia in Pan's Laybrinth, but we'll all be reintroduced to her when she stars in MTV's upcoming sci-fi show, the Shannara Chronicles.
5 of 10
Nicholas Hoult (Marcus Brewer, About a Boy)
We know, Nicholas Hoult is a familiar face these days—plus, Jennifer Lawrence's sometimes BF—but we had to include him just because his transformation into a dude was so spectacular. Next up? X-Men: Apocolypse.
6 of 10
Alexa Vega (Carmen, Spy Kids)
This former snarky spy kid, now going by Alexa PenaVega, has shed her sweet image in favor of spice. In addition to a score of movies coming out in the next couple of years, PenaVega also has a recurring role on Nashville.
7 of 10
Alfie Enoch (Dean Thomas, Harry Potter)
There must be something in the water over at Hogwarts—Alfred Enoch went from sweet side-character to serious leading man, now starring on How to Get Away with Murder.
8 of 10
Josh Peck (Josh, Drake & Josh)
The Oprah-loving oaf you may remember from Drake & Josh is all grown up, and it shows. Shedding both the pounds and the babyface but none of the funny, you can soon catch him on Grandfathered, premiering on Fox this fall.
9 of 10
Nicola Peltz (Katara, The Last Airbender)
Not even a flop like The Last Airbender could dim this rising star. Peltz may not have many credits to her name yet, but she continues to shine as Norman's troubled friend Bradley on Bate's Motel.
10 of 10
Tania Raymonde (Cynthia, Malcolm in the Middle)
She was cute as a button on Malcolm in the Middle as Malcolm's precocious friend Cynthia, but Raymonde is now clearly an adult with a capital A. You can see her as Valerie on The Last Ship.