What is the name of the ghost in Hamlet?

The ghost in Hamlet is King Hamlet, the murdered father of Prince Hamlet. Shakespeare’s stage directions call the apparition simply “Ghost,” but the character identifies himself as Hamlet’s deceased father, and “King Hamlet” is the standard name used to distinguish him from the prince.

The Ghost first appears to guards at Elsinore and later to Horatio and Prince Hamlet. It says that Claudius, Hamlet’s brother, poisoned and murdered him while he slept, then took both his crown and his wife, Gertrude. The Ghost commands Prince Hamlet to avenge the murder but tells him to leave Gertrude’s punishment to heaven.

Hamlet is not immediately certain that the apparition is trustworthy. He worries that it could be a demon exploiting his grief, so he stages a play that reenacts the alleged murder. Claudius’s reaction convinces Hamlet that the Ghost’s accusation is genuine.

Yorick is the dead court jester remembered in the graveyard scene, while Polonius is a court official whom Hamlet kills. Claudius is the murderer and the new king, not the ghost.