Matthew Lewis/YMMV

"JK Rowling : Matthew Lewis, who plays Neville, has undergone a bigger physical transformation than any other person who works in those films to the point that, when I went to the read through of Half Blood Prince, we were all sitting in this great square and they put all the tables from the Great Hall into this big square so everyone’s facing inwards for the read through. And facing me were Dan, and Rupert, and Emma, and Evanna, and Bonnie, and the main lot. And there’s this really big cool guy sitting there, with a bit of stubble and wearing this woolen hat, and a leather jacket, and I didn’t recognize him, and my eyes pass on, and I sort of thought, ‘That will be the guy they’ve got playing Mc Laggen’. And then I thought, ‘Where’s Matthew?’ and I looked at him and my god, when did that happen?"
 * Hollywood Homely: After the third movie for Harry Potter, the makeup crew did a damn good job of uglifying Matthew Lewis for the role. After the last movie, Damn near everyone including the author of the series was shocked to see how good looking Matt really was.


 * What the Hell, Casting Agency? - Averted trope. He fit the description of Neville almost perfectly for the first two movies, but when Matthew Lewis started to hit puberty and losing his babyfat around the third and fourth movies, he was made to wear false teeth, prosthetic ears, and a Fat Suit so he'd still look like his character and not a Hollywood Nerd. He's gone on record saying it was embarrassing when there started being more girls around the set.
 * However, in the last movie he's not wearing any extra prosthetics, mostly because the director didn't feel like it and it fit Neville's Took a Level In Badass for the movie.