William Samuel Cox (1831–1895) was a pioneer of Thoroughbred racing in Australia. He founded the Moonee Valley Racing Club in 1883, on land he leased in 1882. The Cox Plate, a prestigious horse racing event, is named after him.
Other members of Cox's family to contribute to Australian racing include his sons A. H. (Archie) Cox and W. S. Cox, Jr.; the latter's son William Stanley "Bill" Cox; and his son, William Murray Cox. The family was inducted into the Australian Racing Hall of Fame en bloc in 2006.