The appearance of the Ghost is so ambiguous precisely because there is no way of verifying that the Ghost actually is who he says he is and not some malicious spirit who is delighting in the impact that his words are having on poor Hamlet. This is something that is refered to at various points in the play, and most clearly in Act I when Hamlet first meets the Ghost. Note how he greets the appearance of the Ghost and how he responds:
Be thou a spirit of health or goblin damn'd,
Bring with thee airs from heaven or blasts from hell,
Be thy intents wicked or charitable,
Thou comest in such a questionable shape
That I will speak to thee: I'll call thee Hamlet,
King, father, royal Dane:
Hamlet's speech here goes to the heart of the ambiguity. He recognises the possibility that this Ghost could actually be what he pretends to be, but also he makes it clear that he could be "goblin damn'd" and that he might be appearing in the form of his late father with malicious intent. This possibility continues to haunt Hamlet at various stages throughout the play as he tries to establish the truth of what happened to his father and whether it is worth setting himself on the course of destruction to achieve revenge.
Hamlet is one of the famous plays that William Shakespeare wrote and used the ghost in it . the ghost is considered as a main character beside hamlet himself. The ghost is a symbol of instability in Denmark and it is the omen which signifies that something is wrong. In Shakespeare's play, the ghost appeared as his father whom he love and admire. The ghost came to Hamlet to tell him that his father didn't die because of a snake but that there is a real reason no one knows .
The ghost discover a great secret to Hamlet , that his father was killed by Hamlet's uncle who married Hamlet's mother and became the king .
This was a great shock for Hamlet . the ghost was seeking revenge so his soul can go to the heavens as the Christian believed . the ghost gave Hamlet the motivation to take revenge from his father's killer .
The ghost has appeared more than one time in the play , another character saw it but the ghost only spoke to Hamlet . no one could see it even Hamlet's mother although that the ghost appeared in her room once .
The ghost is an important character in the play , it is the actual reason why Hamlet want to take revenge from his uncle . The role of the ghost is to encourage Hamlet to take revenge from his father's killer . Shakespeare used the ghost role wisely and that made it an unique play .