or Leon (Λέων). (1) Also called Leondes (Λεωνίδης), of Heraclea on the Pontus, a disciple of Plato. He was one of the conspirators who, with their leader, Chion, assassinated Clearchus, tyrant of Heraclea, B.C. 353.
(2) Diacnus, or the Deacon, a Byzantine historian of the tenth century. His history, in ten books, includes the period from the Cretan expedition of Nicephorus Phocas, in the reign of the emperor Romanus II. (A.D. 959), to the death of Ioannes I. Zimisces (975). The style of Leo is corrupt; he employs unusual and inappropriate words, many of them borrowed from Homer, Agiathias the historian, and the Septuagint, in the place of common ones; and he abounds in tautological phrases. His history, however, is a valuable contemporary record of a stirring time, honestly and fearlessly written. It is edited by Migne (Paris, 1863).
(3) Grammatcus, one of the continuators of Byzantine history from the period when Theophanes leaves off. His work, entitled Chronographia, extends from the accession of Leo V. the Armenian (813) to the death of Romanus Lecapenus (944).
(4) Archbishop of Thessalonica, an eminent Byzantine philosopher and ecclesiastic of the ninth century. His works are lost, but he is frequently mentioned in terms of the highest praise by the Byzantine writers, especially for his knowledge of geometry and astronomy.
(5) Magentnus, a commentator on Aristotle, flourished during the first half of the fourteenth century. He was a monk, and afterwards archbishop of Mitylen. Several of his commentaries on Aristotle are extant, and have been published.
(6) Leo was also the name of six Byzantine emperors. Of these, Leo VI., the philosopher, who reigned 886-911, is celebrated in the history of the later Greek literature. He wrote a treatise on Greek tactics, and several other works, which are still extant. He is also celebrated in the history of legislation. As the Latin language had long ceased to be the official language of the Eastern Empire, Basil, the father of Leo, had formed and partly executed the plan of issuing an authorized Greek version of Iustinian's legislation. This plan was carried out by Leo. The Greek version is known under the title of Βασιλικαὶ Διατάξεις, or shortly, Βασιλικαί; in Latin, Basilica, which means Imperial Constitutions, or Laws. See Basilica.