The ghost.
'Hamlet' is most basically a revenge play.
Shakespeare wrote two revenge plays: Hamlet and Titus Andronicus.
Revenge is what drives the majority of the action of the play. It is the obligation Hamlet is given by the ghost of his father early on in the play and shapes most of the interactions between characters from that moment on. The complicated morality of revenge is a large part of Hamlet's torment. The revenge motive is what makes Hamlet "feign" madness and establishes the chain of events that leads to Ophelia's madness and death, as well as the enormous body count that amasses by the end of the play.
Why does hamlet hesitate to take revenge? -Apex-
If we take it that Hamlet killed Polonius believing him to be the king, and therefore as a part of his plot for revenge, then Polonius's death, and indirectly Ophelia's arise from his act of revenge. Claudius of course dies from Hamlet's revenge. Gertrude, Laertes and Hamlet die as a result of Laertes and Claudius's plot. Rosencrantz and Guildenstern die just because Hamlet doesn't much like them.
The genre of Hamlet is a revenge tragedy. In this play, the ghost of Hamlet's father returns to get vengeance.
The phrase "Revenge his foul and most unnatural murder" is spoken by the ghost of King Hamlet in William Shakespeare's play "Hamlet." The ghost appears to Prince Hamlet to reveal that he was murdered by his brother Claudius and urges Hamlet to seek revenge for his wrongful death. This pivotal moment sets the stage for the themes of revenge and moral conflict throughout the play.
It's a revenge tragedy.
The theme of Hamlet's second soliloquy is his main internal conflict. Hamlet wants revenge fort his father, but dislikes the idea of exacting revenge. Hamlet becomes frenzied and anxious during the second soliloquy, trying to resolve this conflict.
The Inciting Incident is when the Ghost makes Hamlet swear to get revenge on Claudius for murdering him.
Hamlet was going to act crazy until he got an opportunity to revenge himself on Claudius. Not much of a plan, really.
Why does it take Hamlet so long to take his revenge?