The role of the ghost in Hamlet is twofold: firstly it is to create interest; secondly it is to further the narrative of the play.
Shakespeare recognized that he needed to create interest in the audience from the very first scene of the play.
The play opens with a conversation between Officers of the Watch who patrol the Battlements of Elsinore castle. Their talk is of a ghost who has appeared before twice previously:
" What, has this thing appeared again tonight?"
Immediately this arouses the audience's curiosity. What is the nature of 'this thing' that has appeared?
Horatio, who has not seen the ghost, voices the scepticism that some of the audience may have been feeling:
" Tush, Tush, 'twill not appear".
Suspense is therefore created in the minds of the audience i.e. will the ghost actually appear; does the ghost exist?
The character of Horatio is contrasted with that of Barnardo, Francisco and Marcellus.
Barnardo, Francisco and Marcellus are believers in the ghost, whereas Horatio, who is highly educated, unlike Barnardo, Francisco and Marcellus, questions the ghost existence.
When the ghost finally appears in line 40, cutting short Barnardo's line, it is a moment of high drama resulting from the tension that has been created.
The appearance of the ghost has a huge impact on both the characters and the audience (who together with Horatio see the ghost for the first time). Horatio, sceptic, expresses his fear and amazement in the first line he speaks since seeing the ghost:
"â€¦. It harrows me with fear and wonder".
The audience would have been filled with similar emotions on seeing the ghost, and would have realised that the appearance of the ghost signifies that something is wrong. Elizabethans believed that only people who died without the chance of confessing their sins walked the earth as troubled spirits. Horatio questions the ghost, which disappears mysteriously without speaking. When the ghost fails to speak, it adds to the tension of the scene and the apprehension of the characters.
The ghost makes a second appearance in Act 1 Scene 1 after Horatio has talked about preparations for war with Norway. This sets up the idea in the minds of the audience that the ghost may have something to do with the on going war, but, again the ghost does not speak, and so the audience is left with unanswered questions. This sense of mystery sustains interest and builds suspense in the preparation for scene 2.
At this point the nature of the ghost is ambiguous. Is it a good ghost, it appears in the form of Old Hamlet, or is it an "erring spirit"?
It disappeared when the cock crowed i.e. at first light. The audience would have known that light represent goodness, and dark represents evil. Horatio comments:
"And then it started like a guilty thing".
The audience would have been left wondering why the word 'guilty' had been applied to the ghost. Is the ghost to be trusted, or not? The only thing person who can decide is Hamlet:
"Let us impart what we have seen tonight unto young Hamletâ€¦."
In the next scene Horatio tells Hamlet after some prevarication, that he has seen his fathers ghost. Hamlet is thoroughly depressed because his mother Gertrude, has re-married very quickly. To make matters worse, she has married Claudius, Old Hamlets brother, whom young Hamlet mis-trusts. This is a man
"With one auspicious and one dropping eye"
Which an Elizabethan audience, would have recognized as the sign of a hypocrite.
Horatio describes the ghost to Hamlet, emphasising that the ghost appears to look like Old Hamlet:
"â€¦. A figure like your father armed exactly, cap-a-pe"
And is dressed in armour. Hamlet wants to know everything about the ghost, where it appeared, whether it spoke etc, and through his short, excited questions which he utters in...