Robert Willoughby, 1st Baron Willoughby de Broke, de jure 9th Baron Latimer (c. 1452 – 23 August 1502), KG, of Brook (anciently "Broke"), in the parish of Heywood, near Westbury in Wiltshire, was one of the chief commanders of the royal forces of King Henry VII against the Cornish Rebellion of 1497.
Robert Willoughby was born at Brook (anciently "Broke"), his father's estate then in the parish of Westbury, Wiltshire, now in the later parish of Heywood. He was the son of Sir John Willoughby of the family of the Barons Willoughby of Eresby, seated at Eresby Manor near Spilsby, Lincolnshire. His mother was Anne Cheney, 2nd daughter and co-heiress of Sir Edmund Cheyne (died 1430) of Brook, by his wife Alice Stafford, daughter of Sir Humphrey Stafford of Hooke, and an aunt of Humphrey Stafford, 1st Earl of Devon (died 1469). Edmund Cheyne was the eldest son and heir of Sir Ralph Cheyne (c. 1337–1400) of Poyntington in Somerset and of Brook (three times a Member of Parliament for Wiltshire, Deputy Justiciar of Ireland, Lord Chancellor of Ireland, and Deputy Warden of the Cinque Ports) by his wife Joan Pavely, daughter & co-heiress of Sir John Pavely of Brook.