For a more complete analysis of the characters, please follow the link at eNotes below. But here is a brief run-down:
Fortunato: Fortunato is an Italian friend of Montresor's, and his sworn enemy, whom Montresor has planned to ‘‘punish with impunity.
Luchesi: Luchesi is an acquaintance of Montresor's and Fortunato's, and another wine expert. He never appears in the story, but Montresor keeps Fortunato on the trail of the Amontillado by threatening to allow Luchesi to sample it first if Fortunato is not interested.
Montresor: Montresor is the "I" who narrates the story, telling an unseen listener or reader about his killing of Fortunato fifty years before.