Ruben Arthur Stirton (1901-1966), known to his friends as "Stirt", was an American paleontologist, specializing in mammals, who was active in South America, the United States and Australia. Stirton was closely associated with the University of California Museum of Paleontology, receiving an appointment as curator in 1930 and as its fourth director from 1949 to 1966. His career also saw engaged as a lecturer, associate professorship and then as a professor in 1951, from which time he was director of the University's Department of Paleontology.