(Βασιλίσκος), usurper of the throne of Constantinople, was the brother of the empress Verina, the wife of Leo I., who conferred upon his brother-in-law the dignities of patrician and "dux " or commander-in-chief in Thrace. In this country Basiliscus made a successful campaign against the Bulgarians in A. D. 463. In 468, he was appointed commander-in-chief of the famous expedition against Carthage, then the residence of Genseric, king of the Vandals--one of the greatest military undertakings which is recorded in the annals of history. The plan was concerted between Leo I. Anthemius, emperor of the West, and Marcellinus, who enjoyed independence in Illyricum. Basiliscus was ordered to sail direct to Carthage, and his operations were preceded by those of Marcellinus, who attacked and took Sardinia, while a third army, commanded by Heraclius of Edessa, landed on the Libyan coast east of Carthage, and made rapid progress. It appears that the combined forces met in Sicily, whence the three fleets started at different periods. The number of ships and troops under the command of Basiliscus, and the expenses of the expedition have been differently calculated by different historians. Both were enormous; but while we must reject the account of Nicephorus Gregoras, who speaks of one hundred thousand ships, as either an error of the copyists or a gross exaggeration, everything makes us believe that Cedrenus is correct in saying that the fleet that attacked Carthage consisted of eleven hundred and thirteen ships, having each one hundred men on board. Sardinia and Libya were already conquered by Marcellinus and Heraclius when Basiliscus cast anchor off the Promontorium Mercurii, now cape Bon, opposite Sicily. Genseric, terrified, or feigning to be so, spoke of submission, and requested Basiliscus to allow him five days in order to draw up the conditions of a peace which promised to be one of the most glorious for the Roman arms. During the negotiations, Genserie assembled his ships, and suddenly attacked the Roman fleet, which was unprepared for a general engagement. Basiliscus fled in the heat of the battle; his lieutenant, Joannes, one of the most distinguished warriors of his time, when overpowered by the Vandals, refused the pardon that was promised him, and with his heavy armour leaped overboard, and drowned himself in the sea. One half of the Roman ships was burnt, sunk, or taken, the other half followed the fugitive Basiliscus. The whole expedition had failed. After his arrival at Constantinople, Basiliscus hid himself in the church of St. Sophia, in order to escape the wrath of the people and the revenge of the emperor, but he obtained his pardon by the mediation of Verina, and he was punished merely with banishment to Heraclea in Thrace.

Basiliscus is generally represented as a good general, though easily deceived by stratagems; and it may therefore be possible that he had suffered himself to be surprised by Genseric. The historians generally speak ambiguously, saying that he was either a dupe or a traitor; and there is much ground to believe that he had concerted a plan with Aspar to ruin Leo by causing the failure of the expedition. This opinion gains further strength by the fact, that Basiliscus aspired to the imperial dignity, which, however, he was unable to obtain during the vigorous government of Leo. No sooner had Leo died (474), than Basiliscus and Verina, Leo's widow, conspired against his feeble successor, Zeno, who was driven out and deposed in the following year. It seems that Verina intended to put her lover, Priscus, on the throne; but Basiliscus had too much authority in the army, and succeeded in being proclaimed emperor. (October or November, 475.) His reign was short. He conferred the title of Augusta upon his wife, Zenonida; he created his son, Marcus, Caesar, and afterwards Augustus; and he patronised the Eutychians in spite of the decisions of the council of Chalcedon. During his reign a dreadful conflagration destroyed a considerable part of Constantinople, and amongst other buildings the great library with 120,000 volumes. His rapacity and the want of union among his adherents caused his ruin, which was accelerated by the activity of Zeno, his wife, the empress Ariadne, and generally all their adherents. Illus, the general despatched by Basiliscus against Zeno, who had assembled some forces in Cilicia and Isauria, had no sooner heard that the Greeks were dissatisfied with the usurper, than he and his army joined the party of Zeno; and his successor, Armatius or Harmatus, the nephew of Basiliscus, either followed the example of Illus, or at least allowed Zeno to march unmolested upon Constantinople. Basiliscus was surprised in his palace, and Zeno sent him and his family to Cappadocia, where they were imprisoned in a stronghold, the name of which was perhaps Cucusus. Food having been refused them, Basiliscus, his wife, and children perished by hunger and cold in the winter of 477-478, several months after his fall, which took place in June or July, 477. (Zonaras, 14.1, 2; Procop. De Bell. Vand. 1.6, 7; Theophanes, pp. 97-107, ed. Paris; Cedrenus, pp. 349-50, ed. Paris. Jornandes, de Regn. Suce. pp. 58, 59, ed. Iindenbrog, says, that Carthage was in an untenable position, and that Basiliscus was bribed by Genseric.)