Beleth, Immortal of the Storm is a Unique Oppressor found in the Pandemonium Fortress Level 2 in Act V of Diablo III. He spawns for the Ancient Prison event, as its final boss, and killing him is required to end it.
In combat, he has Orbiter and Frozen Pulse affixes.
During the beta of Reaper of Souls, his title was "Slayer of a Thousand Angels".
In the released game, until patch 2.4, he was named Amok the Breaker, Siegelord, was a Mallet Lord rather than Oppressor, and had Fast, Waller, Thunderstorm and Electrified affixes.
- It is the only unique monster in-game that was changed to its pre-release state in a content patch.
- In demonology, Beleth is one of the demonic kings of Hell.