Deborah Vivien Cavendish, Duchess of Devonshire, was an English aristocrat, writer, memoirist, and socialite. She was the youngest and last-surviving of the six Mitford sisters, who were prominent members of British society in the 1930s and 1940s.

The Mitford family is an aristocratic English family whose principal line had its seats at Mitford, Northumberland. Several heads of the family served as High Sheriff of Northumberland. A junior line, with seats at Newton Park, Northumberland, and Exbury House, Hampshire, descends via the historian William Mitford (1744–1827) and were twice elevated to the British peerage, in 1802 and 1902, under the title Baron Redesdale.