Incubus, in medieval European folklore, a male demon that was believed to seek sexual intercourse with sleeping women. According to one legend, the incubus, and its female counterpart, the succubus, were fallen angels. Union with an incubus was thought to produce demons, witches, and deformed children. The legendary wizard Merlin was said to have been the offspring of such a union. The word incubus is Latin for “nightmare.”(Source: Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation.)
Base on the definition above, these incubus and succubus were like supernatural being wherein no one can stop nor identify their identity. These folklore has been introduce many years ago and until now, there were no concrete evidence if these folklore really exist, and based on the facts that I read, this two supernatural beings will attack when their victims were asleep maybe because of this belief, the popular fiction movie, “a nightmare on elm street” has been created. But the differences of the film was, the main killer which is Freddy, is not doing sexual intercourse with his victims instead he kill them using his steel hand claw, but the whole story was pointing out one common denominator and that is killing them in their nightmare.
Indeed, the world right now have many unsolved mysteries that even the experts find it too difficult to explain and to justify but we, as a human, we find it too easy to explain because of the legends, myths and stories that we know from our ancestors, we can easily made our own stories just to have answers in our mind. Thus, this succubus and incubus are still considered as myth and stories and it is for you to find out if these two supernatural beings are really existed. And it will now depend in to your faith.