The Yuggothians call him "The Beyond One" and Old Whateley calls him "the key to the gate whereby the spheres meet." He is described by Carter who meets him in "Through the Gates of the Silver key" as the All-in-One and One-in-All of limitless being and self--not merely a thing of one space-time continuum, but allied to the ultimate animating essence of existence's whose unbounding sweep--the last, utter sweep which has no confines and which outreaches fancy and mathematics alike. He sits alone on a "throne more hexagonal and otherwise..." Curwen raised him and saw "the face spoken of by Ibn Schacabao." He is believed to have sired Wilbur Whateley and the Dunwich monster. According to William Conover in LOVECRAFT AT LAST, Lovecraft described Yog-Sothoth as having pseudopodic tentacles "(which can pass through the most solid walls)." "Yog doesn't always have long, ropy arms, since he asumes a variety of shapes-solid, liquid, and gaseous-at will. Possibly, though, he's fondest of the form which does have 'em." Yog-Sothoth has no parents, "he always existed." And "those whom Yog-Sothoth touches are never seen again . . . at least, in any recognisable shape. It is not even safe to speak the name of Yog-Sothoth aloud. If we seem to have done so, and yet remain alive, it is merely because our merciful ignorance has caused us to misprounounce it. Yog-Sothoth's wife is the hellish cloud-like entity Shub-Niggurath, in whose honour nameless cults hold the rite of the Goat with a Thousand Young. By her he has two monstrous offspring, the evil twins Nug and Yeb. He has also begotten hellish hybrids upon the females of various organic species throughout the universes of space-time (cf. "'The Dunwich Horror')." In the (PR), Yog-Sothoth is given an actual form. Dr. Clarendon heard an old man in China calling upon this ancient god. He is called by the Tsath the Not-to-Be-Named One. George Rogers represented him in wax as a congery of iridescent globes, yet stupendous in its malign suggestiveness.
("The Case of Charles Dexter Ward," "The Haunter of the Dark," "The Dunwich Horror," "The Whisperer in Darkness," "Through the Gates of the Silver Key," "At the Mountains of Madness") ([P.Rev.] "The Last Test," "The Mound")