The Xothic legend cycle is a series of short stories by American writer Lin Carter that are based on the Cthulhu Mythos of H. P. Lovecraft, primarily on Lovecraft's stories "The Call of Cthulhu" and "Out of the Aeons".
The cycle is centered on a trinity of deities said to be the "sons" of Cthulhu: Ghatanothoa, Ythogtha, and Zoth-Ommog. The five stories that make up the cycle (in chronological order) are "The Dweller in the Tomb" (1971), "Out of the Ages" (1975), "The Horror in the Gallery" (1976), "The Thing in the Pit" (1980), and "The Winfield Heritance" (1981).[1] All these stories are to be found collected, with others, in The Xothic Legend Cycle: The Complete Mythos Fiction of Lin Carter (Chaosium, 1997)
Originally Carter had assembled some of these stories for a volume he planned to call The Terror Out of Time. Stories to have been included in this collection included "The Dweller in the Tomb" (to have been renamed "Zanthu"); "The Winfield Inheritance"; "Zoth-Ommog" (to be renamed "The Terror Out of Time"); "Out of the Ages" and "Them From Outside." The collection was submitted to DAW Books and Arkham House but was unpublished in Carter's lifetime. "Zoth-Ommog" (originally titled "The Horror in the Gallery") was published in the original DAW Books edition of Edward Berlund, ed, The Disciples of Cthulhu (see Cthulhu Mythos anthology) but was omitted from the Chaosium reprint of this anthology; however, the story appears under its original title in The Xothic Legend Cycle: The Complete Mythos Fiction of Lin Carter. "Them from Outside" was scheduled to appear in an issue of Crypt of Cthulhu as "Concerning Them from Outside".
The cycle introduces various mythos elements, such as the Zanthu Tablets, the Ponape Scripture, Father Ubb and the yuggs, and two new Great Old Ones: Ythogtha and Zoth-Ommog. The cycle also features the (fictional) Sanbourne Institute of Pacific Antiquities—perhaps Lin Carter's answer to Lovecraft's Miskatonic University. The lost continent of Mu also figures prominently in the cycle, as do the events that led to its sinking.