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