Prince Hamlet is the title character and protagonist of William Shakespeare's tragedy Hamlet (1599–1601). He is the Prince of Denmark, nephew of the usurping Claudius, and son of King Hamlet, the previous King of Denmark. At the beginning of the play, he is conflicted whether, and how, to avenge the murder of his father, and struggles with his own sanity along the way. By the end of the tragedy, Hamlet has caused the deaths of Polonius, Laertes, Claudius, and Rosencrantz and Guildenstern, two acquaintances of his from childhood. He is also indirectly involved in the deaths of his love Ophelia (drowning) and of his mother Gertrude (mistakenly poisoned by Claudius).

The play opens with Hamlet deeply depressed over the recent death of his father, King Hamlet, and his uncle Claudius' ascension to the throne and hasty marriage to Hamlet's mother Gertrude. One night, his father's ghost appears to him and tells him that Claudius murdered him in order to usurp the throne, and commands his son to avenge his death.

Claudius sends for two of Hamlet's friends from Wittenberg, to find out what is causing Hamlet so much pain. Claudius and his advisor Polonius persuade Ophelia—Polonius' daughter and Hamlet's love interest—to speak with Hamlet while they secretly listen. Hamlet enters, contemplating suicide ("To be, or not to be"). Ophelia greets him, and offers to return his remembrances (tokens of his love interest), upon which Hamlet questions her honesty and tells her to "get thee to a nunnery" (a suggestion of either erotic criticism of hypersexuality, or of escape from the Danish succession crisis that will become bloody.)

Hamlet devises a test to see whether Claudius is guilty: he hires a group of actors to perform a play about the murder of a king in front of the royal court, and has Horatio gauge Claudius' reaction. Claudius demands the play be stopped half through because it causes him to experience guilt. When Claudius leaves the on stage "audience" deeply upset, Hamlet knows that the ghost was telling the truth. He follows Claudius into his chambers in order to kill him, but stops when he sees his uncle praying; he does not want to kill Claudius while he is in a state of grace because Hamlet wants Claudius to suffer in purgatory and Claudius has just attempted to cleanse his sin through confession. A second attempt on Claudius' life ends in Polonius' accidental death.

Claudius, now fearing for his life, sends Hamlet to England, accompanied (and closely watched) by Rosencrantz and Guildenstern. Alone, Claudius discloses that he is actually sending Hamlet to his death. Prior to embarking for England, Hamlet hides Polonius' body, ultimately revealing its location to the King. Meanwhile, the death of Ophelia's father has driven her insane with grief, and Claudius convinces Ophelia's brother Laertes that Hamlet is to blame. Claudius proposes a fencing match between the two. Laertes informs the king that he will further poison the tip of his sword so that a mere scratch would mean certain death. Claudius plans to offer Hamlet poisoned wine if that fails. Gertrude reports that Ophelia has died.

In the Elsinore churchyard, two "clowns", typically represented as gravediggers, enter to prepare Ophelia's grave. Hamlet arrives with Horatio and banters with one of them, who unearths the skull of a jester who Hamlet once knew, Yorick. Ophelia's funeral procession approaches, led by Laertes. Hamlet interrupts, professing his own love and grief for Ophelia. He and Laertes grapple, but the fight is broken up by Claudius and Gertrude.

Later that day, Hamlet tells Horatio how he escaped death on his journey, disclosing that Rosencrantz and Guildenstern have been sent to their deaths instead. A courtier, Osric, interrupts to invite Hamlet to fence with Laertes. Despite Horatio's warnings, Hamlet accepts and the match begins. After several rounds, Gertrude toasts Hamlet, accidentally drinking the wine Claudius poisoned. Between bouts, Laertes attacks and pierces Hamlet with his poisoned blade; in the ensuing scuffle, Hamlet is able to use Laertes' own poisoned sword against him. Gertrude falls and, in her dying breath, announces that she has been poisoned.

In his dying moments, Laertes reveals Claudius' plot. Hamlet stabs Claudius with the poisoned sword, and then forces him to drink from his own poisoned cup to make sure he dies. In his final moments, Hamlet names Prince Fortinbras of Norway as the probable heir to the throne. Horatio attempts to kill himself with the same poisoned wine, but is stopped by Hamlet, so he will be the only one left alive to give a full account of the story. He then wills the throne of Denmark to Fortinbras before dying.