Sir Cyril Astley Clarke, KBE, FRCP, FRCOG, (Hon) FRC Path, FRS (22 August 1907 – 21 November 2000) was a British physician, geneticist and lepidopterist. He was honoured for his pioneering work on prevention of Rh disease of the newborn, and also for his work on the genetics of the Lepidoptera (butterflies and moths).