John Walton Barker, (October 7, 1933 – October 24, 2019) was an American historian and specialist in Byzantine history and classical music. He was the author of a number of works on Byzantine history, including Justinian and the Later Roman Empire (1966) and Manuel II Palaeologus: 1391-1425: A study in late Byzantine Statesmanship (1969). Later in his career, he also wrote books on Richard Wagner, Wagner and Venice (2008), Wagner and Venice Fictionalized: Variations on a Theme (2012).