The ghost of Hamlet's father is a character from William Shakespeare's play Hamlet. In the stage directions, he is referred to as "Ghost". His name is also Hamlet, and he is referred to as King Hamlet to distinguish him from the Prince, his son and the protagonist of the story. He is loosely based on a legendary Jutish chieftain named Horwendill, who appears in Chronicon Lethrense and in Saxo Grammaticus' Gesta Danorum. According to oral tradition, the Ghost was originally played on stage by Shakespeare himself. Source: Wikipedia (en)