John Keith Roberts FRS (16 April 1897 – 126 April 1944) was an Australian physicist who was awarded an 1851 Exhibition Scholarship, and went to England, where he studied under Sir Ernest Rutherford at the University of Cambridge's Cavendish Laboratory. During the Second World War he was the chief scientist at the Royal Navy's Anti-Submarine Experimental Establishment in Fairlie, Scotland, where he oversaw the development of improved techniques for detecting submarines.