In H. P. Lovecraft's Cthulhu Mythos, Ythogtha is the second son of Cthulhu and Idh-Yaa . Ythogtha was the creation of Lin Carter, who first introduced him in the story The Thing In The Pit, one of five tales which together make up The Xothic Legend Cycle. The story tells of how Xanthu , the high priest of Ythogtha, plotted to depose the cult of Ghatanothoa after Ghatanothoa's priests had outlawed all other religions in Mu. The cult of Ghatanothoa had become the dominant religion in Mu following the defeat of T'yog , high priest of Shub-Niggurath, in his quest to vanquish the tyranny of Ghatanothoa forever. Zanthu had hoped to oust Ghatanothoa's cult by freeing Ythogtha from his imprisonment in The Abyss of Yhe from whence he had been thrust into by the Elder Gods. This blasphemous act did not go unnoticed by the Elder Gods, who destroyed Mu and sank it beneath the sea. Zanthu himself abandoned his ritual and fled after discovering the true nature of his god. Following the destruction of Mu, Zanthu and his co-conspirators fled to the fictitious Plateau of Tsang in Inner Mongolia where they all later died. Before his death, Zanthu inscribed his story on The Zanthu Tablets , a series of ten or twelve black jade tablets that also included the sacred rituals and mysteries of Ythogtha. Ythogtha resembles a gigantic humanoid frog or Deep One with only a single huge eye in the center of his forehead like a cyclops and a dense mane and beard of writhing tentacles growing from his head. Like his other siblings Ghatanothoa, Zoth-Ommog and Cthylla, Ythogtha was spawned on a planet orbiting the green star of Xoth. Together with his younger brother Zoth-Ommog, Ythogtha is served by the planarian-like yuggya who are led by Ubb , the Father of Worms. It has been speculated that Xoth itself could be a corruption of Sothis, the Ancient Egyptian or Arabic name for Sirius, the Dog Star.

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• The Thing In The Pit Lin Carter The Xothic Legend Cycle Robert M. Price (ed) Chaosium
• Perchance To Dream Lin Carter The Xothic Legend Cycle Robert M. Price (ed) Chaosium
• Out Of The Aeons Hazel Heald & H.P. Lovecraft The Loved Dead And Other Revisions August W. Derleth (ed) Arkham House.