The Succubus is a female-demon, which appears in dreams, which take the female form to seduce men, mainly though a sexual intercourse. In the religions, a sexual activity with one of these demons may cause various health problems, sometimes even death. In the modern view of the Succubus, she may or may not appear in people's dreams. People which saw her mainly described her a very attractive and seductive. Though in the past they were described as very demonic-like.
They are always female and the male counterpart is known as the Incubus - like all night-time spirits these entities are likely caused by ancient people's experiences with sleep paralysis (though in the case of the Incubus it was also used to cover-up rape and/or unwanted pregnancies).
In the Jewish history, it is believed that the Adam's first wife Lilith before Eve in the Garden of Eden is the first Succubus to exist. She left Adam once she got mated with Samael the Archangel. Though Samael was mated with four queens of the demons.
The Succubi mainly takes the form of a gorgeous-young women, but closer looking at her, people noticed that she has deformed body-parts of various animals. When having the intercourse with the Succubus, the men enter an icy cave, in which men drip out urine on their vulvases.
In the future, people described the succubi as sirens. The Succubus collect the semen of the men they seduced. The male demons use the male semen in order to make human females pregnant. Human children which was created by these demons, appear to be more deformed and have the supernatural abilities.