"The Cask of Amontillado" (sometimes spelled "The Casque of Amontillado" [a.mon.ti.ˈʝa.ðo]) is a short story by the American writer Edgar Allan Poe, first published in the November 1846 issue of Godey's Lady's Book. The story, set in an unnamed Italian city at carnival time, is about a man taking fatal revenge on a friend who, he believes, has insulted him. Like several of Poe's stories, and in keeping with the 19th-century fascination with the subject, the narrative follows a person being buried alive – in this case, by immurement. As in "The Black Cat" and "The Tell-Tale Heart", Poe conveys the story from the murderer's perspective.

Montresor invites Fortunato to sample amontillado that he has just purchased without proving its authenticity. Fortunato follows him into the Montresor family vaults, which also serve as catacombs. For unknown reasons, Montresor seeks revenge upon Fortunato and is actually luring him into a trap, entombing him alive within the catacombs. At the end of the story, Montresor reveals that 50 years have passed since he took revenge and Fortunato's body has not been disturbed.

Scholars have noted that Montresor's reasons for revenge are unclear and that he may simply be insane. However, Poe also leaves clues that Montresor has lost his family's prior status and blames Fortunato. Further, Fortunato is depicted as an expert on wine, which Montresor exploits in his plot, but he does not display the type of respect towards alcohol expected of such experts. Poe may have been inspired to write the story by his own real-life desire for revenge against contemporary literary rivals. The story has been frequently adapted in multiple forms since its original publication.