Poltergeist

Poltergeists were troublesome, haunting ghosts or spirits, notorious for moving or destroying objects, making noises and disturbing people.They were able to levitate and interact with objects, cause knocking sounds, even hit or bite living creatures and men and generally cause uproar and confusion.

In their origin such ghosts had mostly priginally been the Fëar of Elves or Orcs who, put of fear of punishment for evil deeds, refused to enter the Halls of Mandos and instead fled and became lawless and unbound haunts, often wandering or so etimes bound to a specific place.Most of these Ghosts suffered dearly from their miserable residual-existence and were quite distraught, confused or even completely insame.Elves knew these unruly ghosts as Úlath lhain (S."Wild Ghosts") Orcs as Gogoli (Orc."Poltergeists"). Rarely also spirits of mortal men could become Poltergeists, but this was rare since their spirits had to be bound to the Matter of Arda by some greater power, and even so, their ultimate departure to the Timeless Halls was only delayed.

See:
 * Shadow-realm
 * Undead
 * wights
 * Wraiths