Who is Matthew Lewis?

So with this weekend's final release of Harry Potter and the Deathly Hallows, the stweets are buzzing about the stars of the flick and how they have grown up throughout the course of the series. Many of them started out at either age 10 or 11 and now they are young adults at ages 21 or 22. But as I'm getting all this buzz I realize I keep hearing this unfamiliar name Matthew Lewis. I look at pictures and I'm wondering who this guy is. 
If I didn't do my research, I wouldn't even realize that this guy has been playing Neville Longbottom on the HP series for the past ten years. Can you believe that? That's Neville! This has to be the most dramatic transformation we've seen in this series. As compared to how we remember him as a plump kid with crooked teeth. Man, so forget everyone else and keep your eye on this one. You heard it here.