Not My Sister is a 1916 silent film drama directed by Charles Giblyn and starring Bessie Barriscale and William Desmond. It was produced by Thomas H. Ince for Kay-Bee Pictures and distributed by Triangle Film Corporation in Culver City, California.
With no prints of Not My Sister located in any film archives, it is considered a lost film. The film is included among the National Film Preservation Board's list of "7,200 Lost U.S. Silent Feature Films" as of October 2019.