The thesis statement of this story is that revenge is taken to the highest degree, and is executed with total coldness.
Fortunato is the protagonist of this story; he is the most important character in the novel. The young man likes good wine and occasionally he drinks. He was an alcoholic. He insulted and humiliated Montresor many times, but this time it was his last time he ever insulted him ever again. Fortunato was unprepared, and with great pleasure follow Montresor to the catacombs just to get a taste of the Amontillado, and easily falls into the trap of Montresor.
Montresor is the antagonist of this story, he feels a great of bitterness towards Fortunato since apparently Fortunato on several occasions humiliated Montresor. He is a very intelligent character, and it was easy to convince Fortunato since he was already drunk to accompany him to his place with the pretext of giving him to try a new wine (Amontillado).
Another character in the story is Luchresi. He is only a complementary character, only mentioned a couple of times but only mentioning his name helps the protagonist with his revenge and to murder Fortunato.