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

Lieutenant-Colonel Charles Richard John Spencer-Churchill, 9th Duke of Marlborough,, styled Earl of Sunderland until 1883 and Marquess of Blandford between 1883 and 1892, was a British soldier and Conservative politician, and a close friend of his first cousin Winston Churchill. He was often known as "Sunny" Marlborough after his courtesy title of Earl of Sunderland.