Macbeth represents a classic tragedy in that its protagonist travels down a dark path of treachery and violence that inevitably leads to his own downfall and death. Like the protagonists in other classic tragedies, Macbeth is a politically noteworthy figure. He is also still essentially good at the beginning of the play, when his faithful service to Scotland in battle wins him the respect of the king and the honor of a new title, the Thane of Cawdor.

Ironically, it is precisely this respect and honor that trigger Macbeth's corruption—coupled, of course, with the witches’ prophecy, which accurately predicted his new title and promised much greater rewards besides. This pairing of prophecy and realization amplifies Macbeth's ambition. Although many critics see Macbeth's ambition as a classic example of a tragic flaw, others dispute whether Macbeth's lust for power is, in fact, a tragic flaw. Shakespeare scholar Jesse M. Lander notes that in the play ambition and treachery are not unique to Macbeth. Instead, they "permeate the entire world of the play." On this reading, even though Macbeth possesses an unusual concentration of it, ambition is not so much a fatal flaw as part of the social fabric.

Although in many respects the play follows the classic definition of tragedy, Macbeth is notable for being the only tragedy Shakespeare wrote where the villain is also the hero. Macbeth may start out as a good person, but once his ambition gets the better of him and he commits his first act of treachery, he becomes the play's primary source of evil. After he murders Duncan, Macbeth feels compelled to keep killing in order to cover up his first crime and maintain his grip on power. Each new act of violence results in Macbeth's growing detachment from reality as well as increased chaos in the kingdom of Scotland.

Restoring order to the land requires Macbeth's death. And although Macbeth does eventually die for his crimes, he remains unusual as a tragic protagonist in that, from the very beginning of the play, he willingly embraces evil despite also recognizing that it will result in his "deep damnation" (1.7.20). This contradiction creates an important interpretive problem. How can we, as an audience, empathize with such a reprobate protagonist? Or, put another way, how is it possible for the play to feel tragic when the protagonist so obviously deserves his downfall?