George Spencer-Churchill, 6th Duke of Marlborough, styled Earl of Sunderland until 1817 and Marquess of Blandford between 1817 and 1840, was a British nobleman, politician, and peer. The great-grandfather of Sir Winston Churchill, he served as Lord-Lieutenant of Oxfordshire between 1842 and 1857.

George Spencer-Churchill, 5th Duke of Marlborough FSA, styled Marquess of Blandford until 1817, was a British nobleman, politician, peer, and collector of antiquities and books.