Jon Olav Fosse (Norwegian: [ˈjʊ̀nː ˈfɔ̂sːə]; born 29 September 1959) is a Norwegian author, translator, and playwright. In 2023, he was awarded the Nobel Prize in Literature "for his innovative plays and prose which give voice to the unsayable."

Fosse's work spans over seventy novels, poems, children's books, essays, and theatre plays, which have been translated into over fifty languages. The most performed Norwegian playwright after Henrik Ibsen, Fosse is currently—with productions presented on over a thousand stages worldwide—one of the most performed contemporary playwrights globally. His minimalist and deeply introspective plays, with language often bordering on lyrical prose and poetry, have been noted to represent a modern continuation of the dramatic tradition established by Henrik Ibsen in the 19th century. Fosse's work has often been placed within the tradition of post-dramatic theatre, while several of his notable novels have been described as belonging to the style of post-modernist and avant-garde literature, due to their minimalism, lyricism and unorthodox use of syntax.