Carl Koch or Karl Koch was a German film director and writer with many secondary credits including collaborations with his wife Lotte Reiniger, the animator of The Adventures of Prince Achmed.
Koch is perhaps best known as assistant to Jean Renoir, who helped get Koch and Reiniger exit visas from Germany in 1936. Koch and Renoir, during the filming of La Grande Illusion, discovered that Koch's artillery unit had actually fired on Renoir's airplane during World War I.
In 1939, Koch and Renoir began an adaptation of Tosca at Mussolini's invitation. Renoir had to abandon this project when Italy entered the war against France. Koch completed the film as "Carlo Koch", with Luchino Visconti as his assistant.