In medieval European folklore, the female demon said to seduce men in their sleep is a succubus.
Folklore describes a succubus as a demoness who visits sleeping men, often appearing in dreams or taking the form of an alluring woman. The encounters were understood as supernatural seduction and were sometimes believed to drain a victim’s strength, damage his health, or eventually cause death. The male counterpart, said to prey on women, is the incubus.
The word comes from Late Latin succuba, meaning a female lover or paramour, and is related to succubare, “to lie beneath.” The English term is recorded from the late 14th century. Medieval writers also developed elaborate explanations for how demons could father children, including the idea that a succubus gathered semen for an incubus to use.
Modern images often make the succubus a glamorous fantasy character, but older accounts were more overtly religious and frightening. Historical scholars have also connected these legends with experiences such as erotic dreams, nightmares, and sleep paralysis. A harpy, by contrast, is a winged Greek creature rather than the canonical sleep seductress.