Ernst Diesen (6 April 1913 – 14 November 1970) was a Norwegian revue and film actor and theatre director. He was born in Kristiania, and was married to Kari Diesen. He worked for the revue theatre Chat Noir from 1934 to 1942, and then for the Edderkoppen Theatre. He acted in several films, including the comedy films Bør Børson Jr. from 1938, Den forsvundne pølsemaker from 1941, Det æ'kke te å tru from 1942, and Pappa tar gull from 1964. He was theatre director at Chat Noir from 1950 to 1953.