According to medieval folklore, a succubus is a demon that takes the form of a woman in order to have intercourse with a man in his dreams. The name comes from Old Latin, and means to lie under. In Islamic superstition, there is a similar demon called theqarinah orkarina, and in ancient Middle Eastern cultures Lilith was the night demon's name. Whichever name is used, the essential qualities are the same: a demon who tempts men sexually at night and who tries to kill infants at birth.
There are two biblical passages that may refer directly to this kind of demon. One of the Dead Sea Scrolls (4Q184) depicts a being called the seductress who has horns and wings and a multitude of sins in her wings. This being tempts men into sin and ultimately drags them into the Pit. The passage is quite similar to Proverbs 2:18-19, which describes the dangers of the seductress or strange woman. In describing the results of God's judgment on Edom, Isaiah 34:14 (KJV) says, the screech owl also shall rest there, and find for herself a place of rest. The American Standard Version translates lilith as night demon or monster, and the Revised Standard Version uses the name Lilith. Some commentators have proposed that primitive cultures heard the cries of nocturnal animals and attributed them to demons because they had no knowledge of those animals.
And incubus is the male version.