Manifesting as a gigantic snake with the arms of a man, or sometimes a reptilian humanoid creature, Yig is considered to be the god of snakes and serpents everywhere. He feels a fierce devotion to his "children," emerging from his sleep every autumn to punish those who harm them. He does this either by turning them into serpents or serpent-like wretches themselves, or simply sending other snakes to kill them when they sleep.
In times long passed, Yig and his then-mate Coatlicue ruled the crimson cavern of Yoth beneath the subterranean land of K'n-yan, where the two were worshiped as gods by the denizens of Yoth, the Serpent Men. This arrangement came to an end when the Serpent Men transferred their veneration to Tsathoggua, and mighty Yig placed his curse upon them.
One story of Yig tells of a couple from Arkansas in the 1800's who were moving to Oklahoma in search of a better life. On their journey, the woman came across a nest of newborn rattlesnakes; knowing the fear her husband had for these animals, she killed them with the butt of her rifle, to spare him from the sight. Later that year in the fall, having built themselves a cabin and carved out an existence for themselves, the Father of Serpents came for the woman and her family in the night. Sending a swarm of his children to kill their dog, Yig then tricked the woman into killing her husband with an axe, having her believe that he was actually Yig come to take his vengeance. Finally the Snake-God transformed her into a part-human, part-reptile monstrosity, cursing her to wriggle on her belly like a snake for all eternity.
- Mappo no Ryujin, mother
- Rokon, brother
- Coatlicue, former mate
- Ayi'ig, daughter by the Outer Goddess Yidhra
- Voltiyig, son
- The Curse of Yig (1929), by Zealia Bishop and H.P. Lovecraft.
- He also appears as an antagonist in Fantasy Flight Games' Arkham Horror board game.