Consuelo Vanderbilt Balsan (formerly Consuelo Spencer-Churchill, Duchess of Marlborough; born Consuelo Vanderbilt; 2 March 1877 – 6 December 1964) was a member of the prominent American Vanderbilt family.
Her marriage to The 9th Duke of Marlborough has become an emblem of the socially advantageous, but loveless, marriages common during the Gilded Age.