In folklore traced back to medieval legend, a succubus (plural succubi) is a female demon appearing in dreams who takes the form of a human woman in order to seduce men, usually through sexual intercourse. The male counterpart is the incubus. Religious traditions hold that repeated intercourse with a succubus may result in the deterioration of health or even death.
In modern fictional representations, a succubus may or may not appear in dreams and is often depicted as a highly attractive seductress or enchantress, in contrast to the past where succubi were generally depicted as frightening and demonic.
The word is derived from Late Latin succuba "strumpet" (from succubare "to lie under", from sub- "under" and cubare "to lie"), used to describe the supernatural being as well. It is first attested from 1387.
According to Zohar and the Alphabet of Ben Sira, Lilith was Adam's first wife who later became a succubus. She left Adam and refused to return to the Garden of Eden after she mated with archangel Samael. In Zoharistic Kabbalah, there were four succubi who mated with archangel Samael. They were four original queens of the demons Lilith, Agrat Bat Mahlat, Naamah, and Eisheth Zenunim. In later folklore, a succubus took the form of a siren.
Throughout history, priests and rabbis including Hanina Ben Dosa and Abaye, tried to curb the power of succubi over humans.
Not all succubi were malevolent. According to Walter Mapes in De Nugis Curialium (Trifles of Courtiers), Pope Sylvester II (999–1003) was involved with a succubus named Meridiana, who helped him achieve his high rank in the Catholic Church. Before his death, he confessed of his sins and died repentant.
According to the Kabbalah and the school of Rashba, the original three queens of the demons, Agrat Bat Mahlat, Naamah, and Eisheth Zenunim and all their cohorts give birth to children, except Lilith. According to other legends, the children of Lilith are called Lilin.
According to the Malleus Maleficarum, or "Witches' Hammer", written by Heinrich Kramer (Insitoris) in 1486, a succubus collects semen from the men she seduces. The incubi or male demons then use the semen to impregnate human females, thus explaining how demons could apparently sire children despite the traditional belief that they were incapable of reproduction. Children so begotten – cambions – were supposed to be those that were born deformed, or more susceptible to supernatural influences. The book does not address why a human female impregnated with the semen of a human male would not produce a regular human offspring.
In the field of medicine, there is some belief that the stories relating to encounters with succubi bear similar resemblance to the contemporary phenomenon of people reporting alien abductions, which has been ascribed to the condition known as sleep paralysis. It is therefore suggested that historical accounts of people experiencing encounters with succubi may have been in fact symptoms of sleep paralysis, with the hallucination of the said creatures coming from their contemporary culture.