Sybil Rachel Betty Cecile Sassoon, Marchioness of Cholmondeley, CBE (30 January 1894, London – 26 December 1989, Cheshire) was Chief Staff Officer to Director WRNS, WRNS HQ, Admiralty (HMS Pembroke III) from 12 November 1939 until 1946. On 9 February 1945 she was appointed as Supt. of the Women's Royal Naval Service (WRNS) and the following year was made CBE. She belonged to the prominent Sassoon and Rothschild families.