The Children of Yog-Sothoth are a fictional race created by Chaosium in 1994 for the Call of Cthulhu RPG, who were based on Lovecraft's Dunwhich Horror.
The Children of Yog-Sothoth are mortal creatures infused with Yog-Sothoth's essence. Most of them are able to pass for a large member of a specific species if they wear clothing that hides the monstrous elements in its body. Another feature is the unpleasant scent coming from them. Every one of them has a fundamental understanding of magic. They are not born evil, but since nearly all of them are raised by the cults that create them, that usually ends up being their nature. The creation of a Child of Yog-Sothoth involves a blasphemous ritual in which a humanoid or animal is used as an incubator. The mother dies upon giving birth, and usually gives birth to twins, a Child of Yog-Sothoth and a Spawn of Yog-Sothoth.