Incubus - Male Vampire Name

Like a ghoul, this creature is closely linked to a vampire, but unlike both of them, it is a spirit, and not an animated corpse. This creature does not drain its victims of blood nor energy, but will exhaust them to death by coming in every night to have sex with the victim. The victims, worn out and helpless, often die of asphyxiation as the incubus/ succubus is characterized by a heavy, weighty feeling on the victim's chest. (Eastern European)

Information from:
The Natural History of the Vampire
The Vampire Book: The Encyclopedia of the Undead