The unknown masterpiece, or Le chef-d'œuvre inconnu, is a story by the French author Honoré de Balzac. This short text was of tremendous importance in the world of art, for it holds a groundbreaking reflection about artistic creation: what does completion or failure mean, and how is it that technique does not guarantee either.

Paul Cézanne famously said "I am Frenhofer", identifying with the old master around which the story revolves. Pablo Picasso himself was absolutely fascinated by the text, so much that he had his studio moved in the Parisian street named in the story; there, he painted his own masterpiece, Guernica.