Pierre Bayard (born 1954) is a French author, professor of literature and connoisseur of psychology.

Bayard's recent book Comment parler des livres que l'on n'a pas lus?, or "How to talk about books you haven't read", is a bestseller in France and has received much critical attention in English language press.

A few of his books present revisionist readings of famous fictional mysteries. Not only does he argue that the real murderer is not the one that the author presents to us, but in addition these works suggest that the author subconsciously knew who the real culprit is. His 2008 book L'Affaire du Chien des Baskerville was published in English as Sherlock Holmes was Wrong: Re-opening the Case of the Hound of the Baskervilles. His earlier book Who Killed Roger Ackroyd? re-investigates Agatha Christie's The Murder of Roger Ackroyd. His book on Hamlet which argues that Claudius did not kill Hamlet's father remains untranslated into English.