C. Auguste Dupin is an intelligent, pipe-smoking amateur detective living in Paris. He possesses a unique analytical mind, considering himself both a poet and a mathematician, which allows him to think outside the conventional methods of the local police. He prefers to reflect on problems in the dark and utilizes his sharp intellect to solve complex mysteries for financial and personal motives.

Minister D—— is a bold, perceptive courtier who serves as both a mathematician and a poet. He possesses a daring and cunning intellect, matching the analytical skills of Dupin. Recognizing an opportunity for political blackmail, he steals a sensitive document directly in front of its owner, relying on his astuteness to evade the standard investigative tactics of the Parisian police.

Monsieur G—— is the prefect of the Parisian police. He is thorough and methodical, relying heavily on standard search procedures and logical, mathematical principles to conduct his investigations. Despite his diligence, he struggles to solve cases that require thinking beyond conventional police tactics, forcing him to seek outside help.

The unnamed narrator is a close friend and companion to Dupin. He serves as the primary audience for the details of the crime and the investigation. While observant and curious, he generally lacks the exceptional deductive abilities of his friend, frequently asking clarifying questions to understand the complexities of the case.

The queen is a royal figure who receives a highly sensitive letter containing compromising information. Because the letter proves her deception, she is forced to remain silent when it is stolen right in front of her. This silence renders her vulnerable to political extortion and prompts the secret police investigation.

The king is the royal monarch and husband to the queen. His physical presence during the theft of the letter prevents the queen from speaking out against the thief, as she is actively hiding the document's contents from him.