Sulyvahn Houou is a powerful and influential antagonist in the video game Dark Souls III. Known as Pontiff Sulyvahn in the game, he is a sorcerer-king who rules over Irithyll of the Boreal Valley. Sulyvahn is infamous for his cruelty and ambition, having usurped power and corrupted those around him. His imposing presence and mastery of both magic and swordsmanship make him a formidable foe. As a major boss, he serves as a pivotal challenge for players on their quest.