Derek Stanley Brewer (13 July 1923 – 23 October 2008) was a medieval scholar, author and publisher.
Born in Cardiff, Wales, the son of a clerk with General Electric, Brewer read English at Magdalen College, Oxford, where he was taught, among others, by C.S. Lewis. He served as infantry officer with the Worcestershire Regiment and with the Royal Fusiliers during World War II, from 1942 to 1945, then returned to Oxford. He was appointed lecturer at the University of Birmingham, where he remained until 1964, when he moved to Cambridge to take up the position of lecturer in English and then become fellow of Emmanuel College. From 1977 to 1990 he served his college as Master.
Brewer was one of the most recognized Chaucer scholars of modern times—his Chaucer and His World (1978, reissued 2000) "could be said to have started a whole new genre in historical literary biography." He was also the founder in 1972 of an academic press named for him, D.S. Brewer, now Boydell & Brewer, which made a mark publishing scholarly work neglected by the larger presses.
He died in Cambridge, England, a month after the death of his wife Elisabeth. Obituaries in all the main British newspapers and blogs in the US speak highly of his love of literature and the profession, his advocacy of struggling academics of the medieval period to get their work published, his encouragement of female students (a rarity in the medieval field during much of his lifetime), and his courtesy and friendliness.