Gruewl, Bogan Overlord, is a Super Unique Tusked Bogan found in the Winding Cave in Act V in Diablo III. He spawns for the guaranteed event Lost and Forgotten, and is the head of the Lost Tribe.
He oversees the battle of the Nephalem and his followers. Once all of the latter are dead, he jumps down to fight. He has Plagued affix in combat. Killing him completes the event and lifts the curse on a Radiant Chest.