Apparition

Generally, an apparition is an instance of something's appearing, i.e. being seen. The term may refer to:

Supernatural

Apparitional experience, an anomalous, quasi-perceptual experience
Vision (spirituality), inspirational renderings, generally of a future state and/or of a mythical being
Marian apparition, in which the Virgin Mary is believed to have supernaturally appeared
Ghost, the disembodied spirit or soul of a deceased person
Doppelgänger, the ghostly double of a living person
Bilocation, the ability/instances in which an individual or object appears to be located in two distinct places at the same instant in time
Apparition (Harry Potter), a form of teleportation used in the Harry Potter novels