Denis Midgley Arnold, CBE (Sheffield, 15 December 1926 – Budapest, 28 April 1986) was a British musicologist. After being employed in the extramural department of Queen's University, Belfast, he became a Lecturer in Music at the University of Hull, and from 1969 to 1975 was Professor of Music at The University of Nottingham. From 1975 he was Heather Professor of Music at Oxford University. He served as editor of Music & Letters.