Catherine Lucy Wilhelmina Powlett, Duchess of Cleveland (1819–1901), was a British historian and genealogist. Daughter of the 4th Earl of Darlington and later 3rd Duke of Cleveland, she married her cousin, Lord William Powlett. She is known for her work "The Battle Abbey Roll, with some account of the Norman Lineages" (1889), which investigates Norman lineages, and "The Life and Letters of Lady Hester Stanhope" (1897). She dedicated much of her life to historical and genealogical research.