Ghost

Ghosts were a type of visible, and sometimes tangible, disembodied spirit.

Nature

Ghosts were usually thought of as spirits of the dead, and depicted as chalk-white humanoid figures, or looser, floating spirits in shrouds. (COMIC: Ghost Story) Indeed, Arganthone-056 once faced such a spirit, the Ghost of the First Premium Turkey. However, the term was sometimes used to refer to spirits which embodied concepts, rather than deceased mortal — including the Ghosts of Christmas Past, Christmas Present and Christmas Future. (PROSE: The Time of the Toymaker)

In the Prime Universe at least, ghosts were a type of non-corporeal spirit. Like many other spirits, if they had nowhere else to go, ghosts would naturally find themselves in the Spirit Realm. Indeed, if corporeal beings became trapped in the Spirit Realm while living, they could haunt the physical world, appearing as insubstantial “ghosts” indistinguishable from genuinely dead ones. In the course of the Great Ghost Disaster of 1978, the Crew of the Copper-Colored Cupids came to believe that “ghosts and other related spirits can't persist in dimensions which they aren't anchored to – except on occasions when the Spirit Realm is directly connected to the dimension that they’ve entered”. However, all it took for a ghost to anchor themself to a given realm was to possess a physical being native to that universe. (PROSE: The Ghosts and the Machine) Philatel-426's understanding was that one must “possess a soul to become a spirit after death”, and he'd never considered that robots like himself might become genuine, undead ghosts after death until being confronted with Mailbag-431's shade. (PROSE: A Copper-Colored Christmas Carol)

History

Many ghosts resided in the Strange and Wonderful House, but found “other places to haunt” prior to the Fall of the Strange and Wonderful House. (PROSE: Our Strange and Wonderful House: The Fall of the Strange and Wonderful House)

By the 2010s, due to an unidentified threat, the Great Ghost believed his native Spirit Realm, that of the Prime Universe, to be “doomed” and was looking for a way for him his legion of spirits to permanently escape. He intended to do so via ordinary spirit paths, but, when Frankenstein-818's malfunctioning Spirit Realm Gateway opened a Rift between the Spirit Realm and the Cupid Homeworld, took his chance and led his legion out of the Realm through that portal. While the spirits rampaged, looking for bodies to possess across the Multiverse thanks to a flotilla of Fog Ships stolen from the Cupids, Frankenstein built a One-Way Forced Spirit Realm Gateway which, when activated, would send everything around it to the Spirit Realm.

However, before he could use it, Frankenstein was abducted by the spirits and forced to build a Reverse Spirit Realm Gateway to replace the Rift, which the Department of Rifts had sealed. After a short mishap with the One-Way Gateway where Foreman-964, Pythagoras-858, Technophile-963, Igor-1612 and Philatel-426 were briefly transported to the Spirit Realm before being summoned back by Juliet-178 using the reverse switch of the One-Way Gateway, the Cupids managed to send most of the ghosts back to the Spirit Realm. When they tried to return through the Reverse Gateway, they were transformed into clockwork toys of which Madame Tarsa took possession. The Great Ghost, meanwhile, was separated from his host body and sent to parts unknown. (PROSE: The Ghosts and the Machine)

On Halloween night in one universe, Peter Griffin guessed, among other things, that Jenny Everywhere was dressed as "a scary ghost holding a torch", prior to seeing her costume. (COMIC: The Curse of a Fairly Normal Halloween)