An earth god, the father of serpents. Probably from the Lovecraft-revised "Curse of Yig" by Zelia Bishop Reed. In the (PR), Yig appears in a number of stories. He is the Serpent-god worshipped in K'Naa. In American central plains Indian lore he is called the half-human (semi-anthropomorphic) father of serpents and the primary source for the southerly Quetzalcoatl or Kululcan. The Pawnee, Wichita, and Caddo are especially cautious not to interefere with this god's domain. Yig is relentlessly devoted to his children, the snakes. His chosen method of revenge is to turn his victims to a spotted snake. To the Tsath, Yig, given cryptical shrines, is the principle of life symbolized as the Father of all Serpents. He is worshipped with orgies and sacrifices. They use the tail of Yig as their clock, each tail beat is twelve hours. A Tsath year (approx 1.5 surface years) is measured by the annual shedding of Yig's skin.
From a letter from Lovecraft to Donald Wandrei, March 1928: "The deity in question is entirely a product of my own imaginative theogony-for like Dunsany, I love to invent gods and devils and kindred marvellous [sic] things. However, the Indians certainly had a snake-god; for as everyone knows, the great fabulous teacher and civiliser of the prehistoric Mexican cultures (called Quetzalcoatl by the Incan-Aztec groups and Kukulcan by the Mayas) was a feathered serpent. In working up the plot you will notice that I have added another "twist"-which I think increases the effectiveness of the impression. I took a great deal of care with this tale, and was specially anxious to get the beginning smoothly adjusted."
("The Whisperer in Darkness") ([P.Rev.] "Out of the Aeons," "The Mound," "The Curse of Yig")