hag, in European folklore, an ugly and malicious old woman who practices witchcraft, with or without supernatural powers; hags are often said to be aligned with the devil or the dead. Sometimes appearing in the form of a beautiful woman, a succubus is a hag believed to engage in sexual intercourse with sleeping men, causing severe nightmares and leaving the victim exhausted. Although viewed in most lore as the antithesis of fertility, the hag is believed by some scholars to be a remnant of primitive nature goddesses.