Rupert Frank Mills (October 12, 1892 – July 20, 1929) was a professional baseball player. He played part of one season in Major League Baseball for the 1915 Newark Peppers of the now-defunct Federal League, primarily as a first baseman. He batted .201 in 41 games for the Peppers. Born in Newark, New Jersey, Mills attended Barringer High School and the University of Notre Dame, where he studied law. At Notre Dame he starred in football, baseball, basketball and track.