J.K. Rowling can’t unsee Neville Longbottom’s underwear, or Matthew Lewis’

Neville Longbottom he is not! "Harry Potter" alum Matthew Lewis is showing off what's been under his wizard's cloak this whole time in Attitude magazine — and it does not disappoint.

Unless, that is, you're J.K. Rowling.

The British actor poses in an undershirt on the cover of the mag's June issue. Inside, he broods on a chair wearing only an open cardigan and his Emporio Armani skivvies. (You'll have to click over here to see that longbottom. Hogwarts to hottie, indeed.)

However, one person who isn't a fan of the new-and-improved Neville is boy-wizard creator Rowling, who lovingly called out the 25-year-old for revealing a bit too much.

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".@Mattdavelewis Not as bad as watching Dan in Equus, but close. Warn me next time, for God's sake," she wrote in response to the mag's cover reveal on Twitter.

Dan of course is "Harry Potter" star Daniel Radcliffe, who famously went full-frontal during the 2008 Broadway run of "Equus."

An abashed Lewis responded with: "Well, this is awkward. Sorry, Jo…," adding a sad emoticon.

The "Potter" creator didn't leave it at that, though, and attempted to rectify the actor's dashed spirits.

".@Mattdavelewis I will always support you whatever you want to do, Matthew. Now go put some clothes on," she quipped.

Mischief managed!

Lewis has come a long way since being the herbology-loving Gryffindor of the magical franchise. He'll next star in Thea Sharrock's drama "Me Before You" alongside "Game of Thrones" stars Emilia Clarke and Charles Dance, "Hunger Games" actor Sam Claflin, "Doctor Who" alum Jenna Coleman and "Downton Abbey's" Brendan Coyle.

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In preparation for the role of triathlete and personal trainer, Lewis made his way to heartthrob status with his training regimen and muscular selfies, and he's been dubbed "the Internet's new boyfriend" by People magazine. Much of that started when a plain-clothed Lewis stepped out for 2011's "Deathly Hallows Part 2" red carpet and revealed himself to be physically more impressive than lovable Neville.

"I was excited I guess to go on the red carpet on the release of the last film and be me, and not to have to have the fat suit under my t-shirt. It was quite an exciting buzz," Lewis told Attitude.

"I was 21, I was like 'yeah, this'll be cool!' It was never meant to be a 'hey everyone, look at me!' but it was nice to be able to go and be myself. And then obviously a lot of attention focused on it, which I didn't expect at all. I've never considered myself to be good-looking at all. Just average."

Average? That's as likely as Ron out-scoring Harry in a Quidditch match.

Follow me on Twitter @NardineSaad.