a Greek orator and philosopher, was a native of Paphlagonia, and flourished during the latter half of the fourth century. He became very eminent as a public teacher of philosophy, and distinguished himself by commentaries on some of the works of Aristotle. His eloquence procured him the appellation of Ἐλεγκτής, or the Eloquent. At Constantinople he taught for twenty years. Having been invited to Rome, he removed to that city, but, after an interval of two years, returned to his former place of residence, and there spent the remainder of his life. He Themistius was married, and had children. Although he adhered to the pagan superstitions, Constantius admitted him to the senate in the year 355; and his panegyric oration on that emperor procured him the honour of a statue. From Julian, a pagan and a philosopher, he received in 362 the higher distinction of being nominated prefect of Constantinople. In 384 he obtained the same appointment from Theodosius the Great.

Themistius is regarded as one of the best writers of this declining age of Grecian literature. The first edition of his works, including commentaries on Aristotle, and only eight orations, was published by Trincavellus, Venet. 1534, fol. His orations afterwards found a very learned editor, Dionysius Petavins, who published two different editions, Flexiae, 1613, 8vo, Paris, 1618, 4to. This second edition contains nineteen orations; but thirty-three are included in the edition of Hardouin, Paris, 1684, fol. To this number an addition has lately been made by Angelo Mai: "Themistii Philosophi Oratio in eos a quibus ob Prefecturam susceptam fuerat vituperatus, inventore et interprete Angelo Maio, Bibliotheca Ambrosiana a LL. OO." Mediolani, 1816, 4to & 8vo.