Field Marshal Sir Cyril John Deverell, GCB, KBE, ADC, DL (9 November 1874 – 12 May 1947) was a British career military officer who served as Chief of the Imperial General Staff in 1936 and 1937. He fought in the Fourth Anglo-Ashanti War and World War I and later advised the Government on the importance of maintaining the capability to mount an Expeditionary Force for operations on mainland Europe.