In medieval legend, a succubus (plural succubi; from Latin succuba; "prostitute") is a female demon that seduces men (especially monks) in dreams to have sexual intercourse. They draw energy from the men to sustain themselves, often until the point of exhaustion or death of the victim. From mythology and fantasy, Lilith and the Lilin (Jewish), Lilitu (Sumerian) and Rusalka (Slavic) were succubi.
According to the Malleus Maleficarum, or "Witches' Hammer", succubi would collect semen from the men they slept with, which incubi would then use to impregnate women. Children so begotten were supposed to be more susceptible to the influence of demons.
Honoré de Balzac wrote a short story The Succubushttp://www.readbookonline.net/readOnLine/826/ concerning a 1271 trial of a she-devil succubus in the guise of a woman, who amongst other things could use her hair to entangle victims.
From the 16th century, the carving of a succubus on the outside of an inn indicated that the establishment also operated as a brothel.
Appearance
The appearance of succubi varies just about as much as that of demons in general; there is no single definitive depiction. However, they are almost universally depicted as alluring women with unearthly beauty, often with demonic batlike wings; occasionally, they will be given other demonic features (horns, a tail with a spaded tip, snakelike eyes, hooves, etc). Occasionally they appear simply as an attractive woman in dreams that the victim cannot seem to get off their mind. They lure males and in some cases, the male has seemed to fall "in love" with her. Even out of the dream she will not leave his mind. She will remain there slowly draining energy from him.
In modern times
To this day the blame of nocturnal emissions and other sexual occurrences or mysteries are, in some cultures and circles, blamed on a demon of sin such as a succubus.
Experiences of apparent supernatural visitations at night can sometimes occur as effects of hypnagogia.
The succubus is a popular figure in modern fantasy fiction; see succubi in fiction for more information.
Etymology
Mare was also a term for the sighing, suffocative panting, or an intercepted utterance, with a sense of pressure across the chest, which occurring during sleep. These symptoms were also thought to be an incubus (or succubus), a evil preternatural being causing nightmares and/or nocturnal emissions.