Frances Clytie Rivett-Carnac née Greenstock (16 May 1874 – 1 January 1962) was a British sailor who competed in the 1908 Summer Olympics. She was a crew member of the British boat Heroine III, the only boat in the 7 metre class. Because a second British entry failed to make it to the start, the boat was required to complete just one lap of two races to win. Her husband Charles Rivett-Carnac was also a crew member and won Olympic gold. Their granddaughter Cleone Rivett-Carnac was an athlete in New Zealand.