Nonnosus the Historian was a 6th-century Byzantine historian and diplomat during the reign of Emperor Justinian I. He was the son of the diplomat Abraham and undertook his own embassy around 530 CE. His mission took him to the Himyarite Kingdom in southern Arabia, the Aksumites in Ethiopia, and various Arab tribes.

The Byzantine patriarch Photius preserved the only summary of Nonnosus’s lost work in his Bibliotheca, providing the primary source for these details. Photius noted that Nonnosus wrote in a clear style. His sole known work, the History, described this diplomatic mission. Photius’s summary indicates it contained valuable ethnographic and geographical observations on the regions and peoples of the Red Sea and Arabia.

Nonnosus provides a crucial, though fragmentary, Byzantine perspective on the political and cultural landscape of South Arabia and the Horn of Africa on the eve of the Islamic conquests. His account is a significant source for understanding 6th-century Byzantine diplomacy and the interactions between the empires and tribes of the region.