Helene Bertha Amalie "Leni" Riefenstahl (22 August 1902 – 8 September 2003) was a German film director, actress and dancer widely noted for her aesthetics and innovations as a filmmaker. Her most famous film was Triumph des Willens (Triumph of the Will), made at the 1934 Nuremberg congress of the Nazi Party. Riefenstahl's prominence in the Third Reich along with her personal friendship with Adolf Hitler thwarted her film career following Germany's defeat in World War II, after which she was arrested but released without any charges.

Triumph of the Will gave Riefenstahl instant and lasting international fame, as well as infamy. Although she directed only eight films, just two of which received significant coverage outside of Germany, Riefenstahl was widely known all her life. The propaganda value of her films made during the 1930s repels most modern commentators but many film histories cite the aesthetics as outstanding. The Economist wrote that Triumph of the Will "sealed her reputation as the greatest female filmmaker of the 20th century".