Ghost

A ghost is the disembodied spirit of a once living person. Many ghosts live in Hogwarts Castle. These fleshless spirits commonly seem to have either been afraid of death or have some extraordinarily strong connection to the locations they haunt.

In their paranormal state, ghosts are unable to cause much physical influence. They are visible, and appear as a greyish-silver apparition of their former (living) selves. They may not touch or physically move objects, however in passing through an object, they may impart a sensation of icy coldness. Ghosts are either capable of, or pretend to be capable of, almost being able to taste rotten food.

They are also weightless and may fly in any direction. In 1992, a fan was used to blow Nearly Headless Nick away. Ghosts cannot be destroyed, however, they may be petrified with the gaze of a Basilisk. This may be reversed by a Mandrake Restorative Draught, though the method of administration is unclear.

House Ghosts
Each House at Hogwarts has a patron ghost. Each of these ghosts once belonged to their corresponding House. They apparently serve as a representative to their House, as well as serving the role of messenger. It is unknown for how long they may retain this title.

Known Ghosts

 * Bloody Baron
 * Professor Cuthbert Binns
 * Fat Friar
 * Grey Lady[[Image:The Battle of Hogwarts.jpg|thumb|right|150px|The grey Lady, Ghost of Ravenclaw]]
 * Moaning Myrtle
 * Sir Nicholas of Mimsy Porpington (a.k.a. Nearly Headless Nick)
 * Sir Patrick Delaney-Podmore
 * Edgar Clogg
 * A "Ragged Man Wearing Chains" (This ghost in chains could be Jacob Marley, the ghost of Ebenezer Scrooge's dead partner, from Charles Dickens' A Christmas Carol.)
 * A "Knight With An Arrow Sticking Out Of His Forehead." (Possibly, this is the ghost of could be Harold II [1022? - 1066]. He was the last Saxon king of England. He was defeated at the Battle of Hastings in 1066 by William the Conqueror. Harold was killed when an arrow pierced his eye.)
 * The Wailing Widow from Kent

Those last three attended the Sir Nicholas de Mimsy Porpington's 500th Deathday Party.

Behind the scenes

 * In the games, Myrtle may extinguish torches with a touch.
 * In the video game, Harry Potter: Quidditch World Cup, a ghost named Edgar Clogg haunts the Quidditch pitch and provides coaching.