Alexis (or Alexins) I., Comnenus, emperor of Constantinople, born in 1048, died Aug. 15, 1118. He was the son of John Comnenus, who refused the succession bequeathed to him by his brother Isaac. Alexis in his youth served the emperor Michael VII. in the Turkish Avar, and against the rebel Nicephorus Botaniates. He was one of the most faithful adherents of Michael till he was deposed by his rebel enemy, when he offered his services to the new emperor. Nicephorus bestowed honors upon him, and charged him with restoring the peace of the empire, then disturbed by many rebellions. Alexis triumphed over the most powerful leaders of revolt, Bryennius and Basilacius, but his victories excited the jealousy of the emperor and the envy of the courtiers; and when he refused to march against a new rebel, the husband of his sister, his destruction was resolved upon. Escaping by the protection of the empress to the army, of which he was the favorite, he was immediately proclaimed emperor by the soldiers, captured Constantinople in 1081, and gave it up to pillage. Nicephorus was permitted to retire to a convent. Alexis found the empire in internal discomposure, and surrounded by enemies.

On the east the Seljuk Turks, overrunning the provinces of Asia, had spread from Persia to the Hellespont; on the west, the Normans, under Robert Guiscard, after brilliant successes in Italy, were advancing eastward; and new swarms of barbarians from the north, having crossed the Danube and occupied Thrace, had several times defeated the imperial troops. The first measure of Alexis was to conclude a peace with the Turks by abandoning to them the provinces of which they already had possession. Heavy exactions and spoliations of the churches furnished him the means to at once raise an army of 70,000 men, with which he marched for the deliverance of Durazzo, besieged by the Normans. His treaty with the sultan had procured him an auxiliary force of some thousand Turks, and he had even succeeded in enlisting under his banner some of the wild Transdanubians. The battle was fought Oct. 18, 1081; and the Normans, led by Robert and his wife Gaita, gained a complete victory. Robert was now obliged by a revolt of his vassals to return for a time to Italy, which gave Alexis leisure to repel the incursions of the Turks. By means of his navy he contended with doubtful success against them till 1095, but was in despair when he learned that the Turks had availed themselves of the art of some Greek prisoners to build a fleet, with which they were approaching Constantinople. He now addressed himself for aid to the West, declaring that the existence of Christendom was threatened by this new eruption of barbarians.

The capture of Jerusalem by the Moslems, the preaching of Peter the Hermit, and the activity of Pope Urban II., produced a meeting of the Christian princes at Piacenza. The ambassadors of Alexis contributed much toward deciding the princes to join the first crusade. Alexis had thought only of a moderate succor from the "West; when therefore in 1096 the promiscuous armies of the crusaders began to arrive, numbering untold hosts, and led on by the most renowned leaders of Europe, his fears were quite as great as his hopes, and he was glad to give them a quick passage into Asia, where at first the Turks found little difficulty in annihilating them. Godfrey of Bouillon and Hugh, count of Vermandois, encamped during the winter in the environs of Constantinople, and it was only by a skilful display of his military forces that the emperor felt his capital safe. He failed to give them the assistance which he had promised, and in 1097 demanded from the chiefs of the crusade that they should restore to him his ancient possessions in Asia, and should do homage to him for all the territory which they conquered out of certain prescribed limits.

They consented, though Bohemond, the son of the emperor's old enemy Robert Guiscard, long refused, and Tancred passed over into Asia to avoid the public ceremony of doing homage, at which Count Robert of Paris insulted before the world the imperial majesty. Harmony never existed between Alexis and the leaders of the crusades; and though he rendered them important assistance in the siege of Nicaea, and by their aid recovered some important towns of Asia Minor, and the islands of Rhodes and Chios, yet by abandoning the Christians before Antioch, he so outraged Bohemond that that prince returned to Europe, increased his army, and began to wage war in Thrace against Alexis. He, however, gained but slight successes, and soon made peace. In the last years of his life Alexis continued to war against the Turks, and defeated them in great battles in 1115 and 1116. Alexis was an able ruler, valiant, active, and politic; but he was also dissembling and hvpocritical.