Flavins Leo VI, surnamed the Philosopher, a Byzantine emperor, born about 865, ascended the throne in 886, died in 911. He was associated with his father Basil I. in the government two years before he succeeded him. Narrowly escaping from a false accusation of parricide made by the minister Santabaren and the patriarch Photius, he began his reign by banishing one of them and deposing the other. From 887 to 891 he warred against the Saracens in Asia Minor and Italy. The mismanagement of the prime minister Stylianus, who disregarded the privileges of Bulgarian merchants, occasioned a severe war with that people, which Leo terminated in 894 by involving the Bulgarians in hostilities with the Hungarians. The inactivity of the emperor exposed him to a series of conspiracies, and invited new attacks by the Saracens, who in 904 captured and plundered Thessalonica. In 911 they defeated the Greek fleet near Samos. Leo combined the legislative and executive powers in his own person, and extinguished the last remains of the authority of the senate. He was excluded from the communion of the faithful on account of his fourth nuptials, the Greek church tolerating only a second marriage. His title of Philosopher he received for having written several works on theological and profane subjects.

The "Basi-lics," or imperial constitutions, being a Greek translation and revision of Justinian's Corpus Juris, with the addition of subsequent constitutions, were begun under Basil I., and completed under Leo and Constantine Porphyro-genitus. The principal writings attributed to Leo are 33 orations, chiefly on theological subjects, an important treatise on military tactics, and a work on " Oracles," in which the fates of the empire are foretold by the arts of astrology and divination.