John Robert Morris (8 June 1913 – 1 June 1977) was an English historian who specialised in the study of the institutions of the Roman Empire and the history of Sub-Roman Britain.
He is best known for his book The Age of Arthur (1973), which attempted to reconstruct the history of Britain and Ireland during the so-called "Dark Ages" (350–650 A.D.) following the Roman withdrawal, based on scattered archaeological and historical records.
Much of his other work focused on Britain during this time.