East Roman emperor from 474 to 491, was an Isaurian of noble birth, and originally bore the name of Trascalissaeus, which he exchanged for that of Zeno on his marriage with Ariadne, daughter of Leo I., in 468. Of his early life nothing is known; after his marriage (which was designed by Leo to secure the Isaurian support against his ambitious minister Aspar) he became patrician and commander of the imperial guard and of the armies in the East. While on a campaign in Thrace he narrowly escaped assassination; on his return to the capital he avenged himself by compassing the murder of Aspar, who had instigated the attempt. In 474 Leo I. died after appointing as his successor Leo the son of Zeno and Ariadne; Zeno, however, with the help of his mother-in-law Verina, succeeded in getting himself crowned also, and on the death of his son before the end of the year became sole emperor. In the following year, in consequence of a revolt fomented by Verina in favour of her brother Basiliscus, and the antipathy to his Isaurian soldiers and administrators, he was compelled to take refuge in Isauria, where, after sustaining a defeat, he was compelled to shut himself up in a fortress. The growing misgovernment and unpopularity of Basiliscus ultimately enabled Zeno to re-enter Constantinople unopposed (476); his rival was banished to Phrygia, where he soon afterwards died. The remainder of Zeno's reign was disturbed by numerous other less formidable revolts. Since 472 the aggressions of the two Ostrogoth leaders Theodoric had been a constant source of danger. Though Zeno at times contrived to play them off against each other, they in turn were able to profit by his dynastic rivalries, and it was only by offering them pay and high command that he kept them from attacking Constantinople itself. In 487 he induced Theodoric, son of Theodemir, to invade Italy and establish his new kingdom. Zeno is described as a lax and indolent ruler, but he seems to have husbanded the resources of the empire so as to leave it appreciably stronger at his death. In ecclesiastical history the name of Zeno is associated with the Henoticon or instrument of union, promulgated by him and signed by all the Eastern bishops, with the design of terminating the Monophysite controversy.
See J. B. Bury, The Later Roman Empire (London, 1889), i. pp. 250-274; E. W. Brooks in the English Historical Review (1893), pp. 209-238; W. Barth, Der Kaiser Zeno (Basel, 1894).