Erstwhile Susan is a 1919 American silent drama film directed by John S. Robertson, produced and distributed by Realart Pictures. It is based on a 1914 novel Barnabetta by Helen Reimensnyder Martin and later Broadway play Erstwhile Susan by Marian De Forest. Minnie Maddern Fiske starred in the Broadway play in 1916. This film version stars Mary Alden and Constance Binney, then an up-and-coming young actress. This film version, once thought to be lost, survives at the Museum of Modern Art.Erstwhile Susan was the first film by Realart Films, Adolph Zukor's offshoot affiliate of his Famous Players–Lasky enterprise.