Xoth, also known as Zoth, is the green binary star where Cthulhu and his like once lived before coming to the Earth. According to The Xothic Legend Cycle, it is where Cthulhu mated with Idh-yaa to beget Ghatanothoa, Ythogtha, and Zoth-Ommog.
Xoth is also the native home of Ycnágnnisssz and Zstylzhemghi, and was the temporary home of the latter's "husband", Ghisguth, and their progeny, the infant Tsathoggua. Tsathoggua later went to live on Yuggoth. Afterward, he fled to Cykranosh to escape Cxaxukluth's cannibalistic eating habits.
According to Friedrich von Junzt, Xoth is located in the same star cluster as the planets Abbith and Ymar. (EXP: "The Thing in the Pit")