Directed 6 different actors in Oscar-nominated performances: Cecil Kellaway, Loretta Young, Celeste Holm, Elsa Lanchester, Josephine Hull, James Stewart and Richard Burton. Hull won an Oscar for Harvey (1950).
Father of Robert J. Koster.
Grandfather of Kevin Koster.
He discovered Bud Abbott and Lou Costello working at a nightclub in New York. He returned to Hollywood and convinced Universal to hire them. Their first picture, which featured the "Who's on First" routine, was One Night in the Tropics (1940). The female lead in that picture was Peggy Moran, who would later marry Koster. At the time they did not know each other.
He was forced to flee Germany after Adolf Hitler came to power when he knocked out a Nazi SA officer who insulted him in a bank. The manager of the bank, a friend of Koster's, saw the incident, shoved some money into his pocket and told him to go directly to the train station. Koster took his advice and made his way to France, then to America. Ironically, after World War II started, Koster was considered an enemy alien and was restricted to his house in the evening. Charles Laughton visited him and played chess with him.
When he married Peggy Moran in 1941 he promised her he would put her in every movie he made from then on. He did, but it was her statue. Usually it is a sculptured head on a mantelpiece or a piano or desk. In The Robe (1953) he commissioned a Grecian bust of her that appears prominently in a Roman villa.