It looks like the Korean-language version of Diablo III may have jumped the game a bit on confirming another character class for the upcoming Blizzard title.
The page dedicated for the game's character classes showed the Barbarian, Witchdoctor, Wizard and Monk, though the final, still unconfirmed class, didn't show any additional information when it was clicked on.
It should come as a surprise that the Monk appears to be coming to the latest iteration of Diablo. The Monk was a playable class in the original title along with the Barbarian, Bard, Rogue, Sorcerer and Warrior.
I suspect we'll be getting some sort of official confirmation on this in the coming hour or so with Blizzcon just moments from going live.