Tormented Behemoth, Horror of the Pit, is a Unique Unburied found in the Halls of Agony Level 2 in Act I of Diablo III. He spawns for the A Stranger in Need event, always in the very end of the dungeon, in the pit adjascent to the exit to the Highlands Passage. Killing him is required to end the event.
In combat, he has Mortar affixes.