Ghost character

In playwriting, a ghost character is a character who is mentioned as appearing on stage but neither says nor does anything but enter, and possibly exit. They are generally interpreted as editing mistakes, indicative of unresolved revisions to the text. If the character was intended to appear but say nothing, it is assumed this function would be clearly identified in the play.
The term is most often used in discussion of Elizabethan and Jacobean plays, which are assumed to have existed in several revisions, only one of which is usually published. It is most associated with the works of William Shakespeare and is often thought to be evidence that the published version of the play is taken from his foul papers.
What the presence of such a character means often varies by play and by commentator. Some commentators claim that the ghost character in Timon of Athens, for example, proves the play's weakness and unfinished nature, though such an argument is rarely used...