An incubus (plurual incubi) is a male demon that has sexual intercourse with sleeping women.
The female counterpart of an incubus is a succubus. Their mythology overlaps somewhat with that of vampires, as succubi are said to drain their male victims’ vitality, and in some instances, this extends to drinking their blood. Succubi have been depicted variously as grotesque or extremely attractive.
The offspring resulting from the coupling of an incubus and a human female, or of a succubus and a human male, is known as a cambion. These beings could be deformed children, demons, or witches. In Arthurian legend, Merlin the wizard is claimed to be a cambion.