The Graeae are three witches / sisters in Greek mythology. In the Marvel fictional universe it is mentioned they are the offspring of Echidna but they have not yet made an appearance in Marvel Comics.
Background[]
The Graeae are granddaughters of the Elder God Set, as the offspring of Set's son Phorcys who mated with Ceto, a sea monster. The sisters are witches, that look like ancient women (hags) and they share one eye and one tooth. Whose names are Enyo, Deino (or Dino), and Pemphredo (or Pephredo).
Also known as the Grey Ones of Hellas were individually known as Pephredo, Enyo and Deino are were an avatar of Our Ladies of Sorrow. (EXP: "Our Ladies of Sorrow")
They were the oracle of men, but that role was then taken over by the keeper of secrets. They tried to retake that role through their daughter, clashing against the Harlot. (EXP: Hexed: The Harlot and the Thief)