The Elder Stain
Great Old Ones
The Old ones such as Cthulhu, Shub-Niggurath, Father Dagon, Mother Hydra, Cthugha, Hastur, Ithaqua, Lliogor and Tsathoggua are not as powerful as the Outer Gods, nor do they have as much influence. Nonetheless, they are served in the stories by devoted congregations of worshippers, made up of both human and non-human cults. They live or are trapped, for the most part, within the earth sphere.
Click here for The wikipedia page about the Great Old Ones