Le Chevalier C. Auguste Dupin [oɡyst dypɛ̃] is a fictional character created by Edgar Allan Poe.

Using what Poe termed "ratiocination", Dupin combines his considerable intellect with creative imagination, even putting himself in the mind of the criminal.

Dupin is from what was once a wealthy family, but "by a variety of untoward events" has been reduced to more humble circumstances, and contents himself only with the basic necessities of life.

In "The Murders in the Rue Morgue", he travels through city streets; in "The Mystery of Marie Rogêt", he is in the wide outdoors; in "The Purloined Letter", he is in an enclosed private space.

He makes in silence a host of observations and inferences....While discussing Dupin's method in the light of Charles Sanders Peirce's logic of making good guesses or abductive reasoning, Nancy Harrowitz first quotes Poe's definition of analysis and then shows how "Poe the semiotician is running the gamut of possibilities here—inferences, reasoning backwards, visual, sensual and aural signs, reading faces.

According to biographer Joseph Krutch, Dupin is portrayed as a dehumanized thinking machine, a man whose sole interest is in pure logic.

[14] According to Krutch, Dupin's deductive prowess is first exhibited when he appears to read the narrator's mind by rationally tracing his train of thought for the previous fifteen minutes.

His attitude towards life seems to portray him as a snob who feels that due to his aptitude normal human interaction and relationships are beneath him.

[19] Dupin's method also emphasizes the importance of reading and writing: many of his clues come from newspapers or written reports from the Prefect.

[20] Poe may have derived the name "Dupin" from a character in a series of stories first published Burton's Gentleman's Magazine in 1828 called "Unpublished passages in the Life of Vidocq, the French Minister of Police".

The first Dupin story coincided in Graham's Magazine with Poe's review of a translation of Louis de Loménie's biographical sketches.

[8] It is sometimes speculated that Poe conceived the idea of Dupin from his investigation of the authenticity of an automaton called The Turk, which he published in his essay "Mälzel's Chess Player".

The character served as the prototype for many that were created later, including Sherlock Holmes by Arthur Conan Doyle and Hercule Poirot by Agatha Christie.

[33] Brander Matthews wrote: "The true detective story as Poe conceived it is not in the mystery itself, but rather in the successive steps whereby the analytic observer is enabled to solve the problem that might be dismissed as beyond human elucidation.

In children's book The Vile Village, Count Olaf disguises himself as "Detective Dupin" in order to falsely accuse the protagonists of murder.

In the comic series The League of Extraordinary Gentlemen, an aged Dupin appears as a minor character; we first meet him shortly after Mina Murray and Allan Quatermain arrive in Paris, France in late June 1898.