Ghost

Ghosts are the lingering spirits of the deceased. Ghosts typically exist where the deceased have unfinished business in the world of the living, or died under unusual circumstances. They are often translucent and pale, although some retain an appearance closer to their original. Ghosts are incorporeal beings, capable of moving through solid objects. Depending on the variety, they can only be harmed by silver, magic or holy objects and scripture. They are not necessarily hostile, and some are not even aware of their state. Ghosts can be contacted or summoned through necromancy.

Source
Although different words are used, the idea of lingering spirits has existed in various cultures since pre-literate times.

Media
Ghost appear in the following media:

Games

 * - "Ghost" is the name of a space ship
 * Might & Magic X: Legacy
 * - "Ghost" is the name of a space ship
 * Might & Magic X: Legacy
 * - "Ghost" is the name of a space ship
 * Might & Magic X: Legacy
 * Might & Magic X: Legacy
 * Might & Magic X: Legacy
 * Might & Magic X: Legacy
 * Might & Magic X: Legacy

Movies and Series

 * Supernatural - TV-Series 2005 - ?
 * Ghostbusters - Movie from 1984
 * Ghostbusters II - Movie from 1989
 * Casper - Animated series, first produced in 1945
 * Casper - Movie from 1995
 * Poltergeist - Movie from 1982
 * Amityville Horror - 1979
 * Ghost Whisperer - Series 2005–2010
 * A Chinese Ghost Story - Movie from 1987
 * Ghost - Movie from 1990
 * Beetlejuice - Movie from 1988