Ghosts are beings that are deceased from their physical bodies. They can be in either human or animal form. Ghosts in real life have been the focus of many stories, comics, films, and telivision series, as well as a staple of being featured in Halloween deccorations.
In the fanon of The Alliance of Super Girls, a type of ghost appears in this series known as "halfas", half human, half ghosts. These halfas are from the series, Danny Phantom, which has a majority of ghost characters.