Letter from an Unknown Woman is a novella by Austrian writer Stefan Zweig. The work first appeared in the 1 January 1922 issue of the Viennese Neuen Freien Presse, before being published in book form as part of the collection Amok: Novellen einer Leidenschaft. The novella tells the story of an author who, while reading a letter written by a woman he does not remember, gets glimpses into her life story. It is generally considered to be Zweig's most famous work of fiction.

Stefan Zweig was an Austrian writer. At the height of his literary career, in the 1920s and 1930s, he was one of the most widely translated and popular writers in the world.