Nikephoros Kallistos, also Nikephoros Kallistos Xanthopoulos (Greek: Νικηφόρος Κάλλιστος Ξανθόπουλος), was a monastic, an ecclesiastical historian, and writer of literary works of the early fourteenth century. He has been called the last of the Greek ecclesiastical historians.
Little is known his life. Nikephoros was born about 1256 and was a native of Constantinople. He was a cleric attached to the Great Church, Hagia Sophia, and became a monk later in his life. He was trained in the florid, rhetorical style of Renaissance Byzantine historiography of the thirteenth and fourteenth centuries. He also taught rhetoric and theology. He died about 1335.
Nikephoros is noted for his 23-volume Ecclesiasticae Historiae (Church History), of which only the first 18 volumes survive. These volumes, based on the manuscript library available to him, cover the history of the period from the origins of Christianity to the execution, in 610, of emperor Phocas who had usurped the throne from emperor Maurice. From a table of contents of the lost appendix of five volumes, the chronicle continued a summarization of the events until the death in 912 of emperor Leo VI (the Wise). As the Historiae was dependent on the earlier works of Eusebius of Caesarea, Evagrius Scholasticus, Sozoman, and others, apparently without critical assessment, its value is dependent upon the quality of the sources. As the Historiae is a product of the times of Byzantine humanism, it is written in an affected style that often impedes textual clarity.
Nikephoros’ other works include commentaries on the writings of the patristic Greek theologian Gregory the Theologian and of the monk John Climacus as well as treatises on the annual cycle of Orthodox services annotated with Lenten and Paschal hymnody. His writings also include original liturgical orations in prose and poetry and on secular themes in verse and rhetorical forms.