James Douglas Howard-Johnston (born 12 March 1942) is an English historian of the Byzantine Empire.
His approach to Byzantium follows that of Edward Gibbon and concentrates on comparisons between the Byzantine state and its Western counterparts.
Howard-Johnston has also done research on Late Antiquity, especially the Roman–Persian Wars and the early history of Islam.
Later, he was University Lecturer in Byzantine Studies and Fellow of Corpus Christi College, Oxford, until his retirement in 2009.
"[4] Howard-Johnston is a stepson of the historian Hugh Trevor-Roper and grandson of Douglas Haig.