Yog-Sothoth has some connection to the mysterious Old Ones mentioned in "The Dunwich Horror" (1929), but their nature, their number, and their connection to Yog-Sothoth are unknown.
In The Case of Charles Dexter Ward, its name is part of an incantation that could revive the dead (and with some of the syllables reversed, slay the creature raised): Y'AI'NG'NGAH YOG-SOTHOTH H'EE-L'GEB F'AI THRODOG UAAAH .