Charles Richard John Spencer-Churchill, 9th Duke of Marlborough KG, TD, PC (13 November 1871 – 30 June 1934), 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.
Born at Simla, India, Marlborough was the only son of George Spencer-Churchill, 8th Duke of Marlborough, and Lady Albertha Frances Anne, daughter of James Hamilton, 1st Duke of Abercorn. He was a nephew of Lord Randolph Churchill and a first cousin of Winston Churchill, with whom he had a close and lifelong friendship. He was 4th cousin, 2 times removed of Diana, Princess of Wales. He was educated at Winchester College and Trinity College, Cambridge.
Marlborough entered the House of Lords on the early death of his father in 1892 and made his maiden speech in August 1895. In 1899, he was appointed Paymaster-General by Lord Salisbury, a post he held until 1902. He was then Under-Secretary of State for the Colonies under Arthur Balfour between 1903 and 1905. He was sworn in as a member of the Privy Council in 1899.