Yhagni is the female or hemaphroditic cousin of Hastur and Cthulhu, who is known for her disgusting appearance and insane power. The other Great Old Ones saw her as a major threat and had her locked deep in the Temple of Pillars in the dephs of Kyartholm, which is hidden somewhere in the Northern Hemisphere. She is believed to appear as a formless, maggot-like creature, though her true appearance is unknown.