A Demon that takes the form of a man and has sexual relations with women; the female equivalent is the Succubus. The incubus is linked with nightmares; mara was the Old English term for the demon that brought evil Dreams. Henry Fuseli brought both aspects together in his famous painting The Nightmare (1781). Incubi were frequently regarded as consorts of Witches. In the Middle Ages, the incubus became a convenient explanation for an illegitimate birth. Merlin was believed the son of a nun and an incubus. The medieval attitude towards incubi is well depicted in The Devils of Loudun (1952) by Aldous Huxley, filmed as The Devils (1971), based on a legend that also inspired the title story of The Devil in a Nunnery (coll 1914) by Francis Oscar Mann (1885-1935), where the Devil was no more than a wandering Minstrel whose songs reminded the nuns of their sexual urges.
The incubus is more common in Supernatural Fiction than fantasy. The image has become attached to the legend of Vampires, who are the modern demon lovers. Although incubi were often blamed for abnormal births in Gothic Fantasy they seldom appeared in Victorian fiction. Some writers returned to the concept of children spawned through elemental Possession, as in Algernon Blackwood's Julius LeVallon (1916) and its sequel, The Bright Messenger (1921). Aleister Crowley resorts to Satanism for the same results in Moonchild (1929). The incubi inferences are kept low-key in To the Devil – A Daughter (1953) by Dennis Wheatley, which continues the Satanist theme. The novel that reintroduced the incubus was Rosemary's Baby (1967) by Ira Levin, where the Devil-spawned child is beheld as a new Satanic Messiah, a theme developed in extremis in the Omen movies. In addition to The Doll who Ate His Mother (1976 US) and To Wake the Dead (1980; rev vt The Parasite 1980 US) by Ramsey Campbell, a number of erotic horror novels have exploited the incubus theme; they include Incubus (1976) by Ray Russell (1924-1999), where a serial rapist turns out to be possessed by a supernatural agency, The Woman who Slept with Demons (1980) by Eric Ericson (1925- ), and the witchcraft sequence Coven (1991) and Incubi (1991) by Edward Lee (real name Lee Edward Seymour; 1957- ).
In the Beginning (1927) by Norman Douglas, which is fantasy, considers the real attitude towards a divinely begotten son in the ancient world. In the Cray Ormeru series by Phyllis Eisenstein, the hero discovers that he is the child of an incubus. [MA]