Incubus aka Incubi, male shaped demons who seek out women are dangerous nightmare demons attacking women at nights that the victim may think was all a dream. Incubus and Succubus are both sex demons who induce a sexual sleep (demon sleeping with the victim) that can eventually kill their victims. The demons sexually feed on the life force of their victims through this form of sin.
They are male demon nightmares, ghosts that sit on the sleeper's chest and cause nightmares. Incubus are also lovers of witches, and the male counterpart to succubus, energy sucking spirits of sexual lusting.
Incubus demons take the form of males to have sexual intercourse with women. An Incubus may do this to father a child (Cambion), as in the legend of Merlin creating a half-demon offspring. Repeated intercourse with an incubus demon or succubus demon will end in the loss of health or even death of the victim.
Other Incubus stories include a feeling of something walking on the bed, finally kneeling on the victim's chest. The victim then experiences sleep paralysis and cannot move. Many victims claim that the demon resting on their chest makes it difficult to breathe.