Brock O'Hurn Is The Sexiest Santa You'll See

Brock O'Hurn and his legendary man bun are out to prove they're more than just a one-trick pony ... so they're giving ol' St. Nick a totally new, much more beefed-up makeover.

O'Hurn has been tapped to play sexy, shirtless Santa in an ad for Icelandic Glacial Water this holiday season with model Iskra Lawrence. You can see from the pics -- O'Hurn's right in his element -- shirtless with his hair flowing ... with the not-so-subtle addition of a Santa suit.

The ad's plot isn't quite clear, but that doesn't matter ... not like you'll be looking at the water anyway.