Quest boss

Quest bosses are superuniques (and sometimes act bosses) who must be defeated to finish quests and advance through the game. Only one is known so far, but more will be added as they are revealed by the development team.

Leoric

The Skeleton King returns in Diablo III, and he's up to his old skeleton-summoning tricks. He's found sitting on his throne, must be awakened by the use of a quest item, and does not return in a good mood. Leoric wields a gigantic hammer and commands a vast army of the undead. He is a quest boss and was the final creature to defeat in the Blizzcon demo build (October 2008.) See The Skeleton King quest article for more details.