Revenge is the central theme in "The Cask of Amontillado." Montresor, the narrator, meticulously plans and executes his vengeance against Fortunato, who he believes has wronged him. Montresor's idea of revenge is not just about punishing Fortunato but doing so in a way that leaves him unpunished by the law and fully recognized by his victim. This story explores the dark and consuming nature of revenge, highlighting how it can lead to a calculated and cold-blooded act.

Montresor's philosophy of revenge is clear from the beginning. He states,

A wrong is unredressed when retribution overtakes its redresser. It is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong.

Montresor believes that for revenge to be complete, the victim must be aware of who is enacting it and why. This belief drives him to ensure that Fortunato is sober enough to understand his fate as he is walled up in the catacombs. Montresor's satisfaction comes from Fortunato's realization of his doom, as shown when Fortunato cries out, “For the love of God, Montresor!” This acknowledgment fulfills Montresor's requirement for revenge, providing him with closure.

Montresor's desire to "punish with impunity" is another critical aspect of his revenge. He wants to ensure that he faces no legal consequences for his actions. Fifty years after the murder, Montresor reflects on his crime with no hint of remorse, suggesting that he has achieved his goal of perfect revenge. His ability to recount the story without suspicion indicates that he has successfully punished Fortunato without facing retribution himself.

The symbolism of the Montresor family coat of arms further underscores the theme of revenge. It features a foot crushing a serpent whose fangs are embedded in the heel, representing Montresor's view of himself as justified in punishing Fortunato for past injuries. The motto, "No one attacks me with impunity," signifies Montresor's vow to seek revenge without facing consequences. This imagery and motto highlight Montresor's determination to avenge perceived insults, reinforcing the story's exploration of vengeance and retribution.

Despite Montresor's success in enacting his revenge, the story suggests that he cannot escape his own conscience. He appears to be confessing to the murder on his deathbed, indicating that guilt may have lingered despite his outward success. This aspect of the story suggests that while one might avoid external punishment, internal guilt can be an unavoidable consequence of revenge.