John George Vanderbilt Henry Spencer-Churchill, 11th Duke of Marlborough, was a British peer. He was the elder son of the 10th Duke of Marlborough and his wife, the Hon. Alexandra Mary Hilda Cadogan. He was known as "Sunny" after his courtesy title of Earl of Sunderland.

John Albert Edward William Spencer-Churchill, 10th Duke of Marlborough,, styled Marquess of Blandford until 1934, was a British military officer and peer.