The ghost is the first thing we are introduced to in the play. It is seen by two guards and Horatio. The guards first refer to it as "the thing" then the "apparition." This is a deliberate ambiguity used to show the fear of the guards and to evoke the curiosity of the audience.

The ghost is a very important character in Hamlet though it appears in few scenes. Its importance rises from the fact that it is through the ghost that we get to know how the father of Hamlet died before the play started. When Hamlet sees the ghost of his father, the latter tells him about "a murder most foul." He tells hamlet that he was poisoned by his own brother Claudius.

But, the ghost is not important just because it is a prologue ghost but rather because it is also a revenge ghost. The...