Maurice Hugh Keen OBE FBA FRHistS FSA (30 October 1933 – 11 September 2012) was a British historian specializing in the Middle Ages.
Keen's father had been the Oxford University head of finance ('Keeper of the University Chest') and a fellow of Balliol College, Oxford, and after schooling at Winchester College, Maurice became an undergraduate there in 1954.
He was a contemporary and lifelong friend of Tom Bingham, later the Senior Law Lord, as well as of the military historian, Sir John Keegan, whose sister Mary he married.
Keen's first success came with the writing of The Outlaws of Medieval Legend while still a junior research fellow at The Queen's College, Oxford, 1957–1961.
The book redefined in several ways the concept of chivalry, underlining the military aspect of it.