Entity   Anything that exists or may be supposed to exist; being

Gateway    A portal to other areas, dimensions, etc.; supposed to be in many cemeteries

Ghost    The visible, or slightly visible entity of a deceased human or animal

Incubus   A demon supposed to descend upon sleeping persons with whom it sought have sexual intercourse. Compare Succubus.

Life Force    The part of a human that may be supposedly separated after death; includes emotions, intelligence, personality, etc.

Orb   The "life force" or "spirit" of an individual, that is usually seen in the form of a white/transparent circular shape; argued by critics to be simply moisture on the camera.

Phantom    An airy spirit; specter; entity; apparition

Poltergeist    A ghost or spirit reputed to make its presence known by any kind of clatter, as knockings and the noises of moving objects.

Specter    A phantom of the dead or disembodied spirit; especially, one of a grisly or horrible nature; ghost; apparition.

Spirit    The human soul after leaving the body

Succubus   One of a class of demons in the female form fabled to have intercourse with men in their sleep.