American mathematical physicist, educator, and science administrator.

Mason completed his undergraduate work at the University of Wisconsin (1898) and received his Ph.D. degree from the University of Göttingen in 1903. His first position, as an instructor in mathematics at the Massachusetts Institute of Technology, Cambridge (1903–04), ended with an appointment as an assistant professor of mathematics at the Sheffield Scientific School at Yale (1904–08). Mason then returned to his alma mater as professor of mathematical physics (1908–25). During World War I he invented several devices for submarine detection. He served as president of the University of Chicago (1925–28), then as director of natural sciences at the Rockefeller Foundation (1928–29), and as president of the foundation (1930–36). Mason's last major appointment was as a member of the executive council of the California Institute of Technology and chairman of its council to direct construction of the Palomar Observatory (completed in 1948).

Mason's special interest and contributions lay in mathematics (differential equations, calculus of variations), physics (electromagnetic theory), invention (acoustical compensators, submarine-detection devices), and the administration of universities and foundations. He was the author of The New Haven Mathematical Colloquium (1910) and contributed numerous papers on mathematical research and electromagnetic field theory to scientific journals.