Justus D. Barnes, named George Barnes in some sources, was an American stage and film actor. He is best known for his role in the 1903 silent short The Great Train Robbery, which the American Film Institute and many film historians and critics recognize as the production that first established the Western genre, setting a new "narrative standard" in the motion picture industry. Kim Newman says it is "probably the first Western film with a storyline".

The Great Train Robbery is a 1903 American silent film made by Edwin S. Porter for the Edison Manufacturing Company. It follows a gang of outlaws who hold up and rob a steam locomotive at a station in the American West, flee across mountainous terrain, and are finally defeated by a posse of locals. The short film draws on many sources, including a robust existing tradition of Western films, recent European innovations in film technique, the play of the same name by Scott Marble, the popularity of train-themed films, and possibly real-life incidents involving outlaws such as Butch Cassidy.