(Βασίλειος ὁ Μακεδών), emperor of the East, one of the most extraordinary characters recorded in history, ascended the throne after a series of almost incredible adventures. He was probably born in A. D. 826, and is said to have been the descendant of a prince of the house of the Arsacidae, who fled to Greece, and was invested with large estates in Thrace by the emperor Leo I. Thrax. (451-474.) There were probably two Arsacidae who settled in Thrace, Chlienes and Artabanus. The father of Basil, however, was a small landowner, the family having gradually lost their riches; but his mother is said to have been a descendant of Constantine the Great. At an early age, Basil was made prisoner by a party of Bulgarians, and carried into their country, where he was educated as a slave. He was ransomed several years afterwards, arrived at Constantinople a destitute lad, and was found asleep on the steps of the church of St. Diomede. His naked beauty attracted the attention of a monk, on whose recommendation he was presented to Theophilus, surnamed the Little, a cousin of the emperor Theophilus (829-842), who, a diminutive man himself, liked to be surrounded by tall and handsome footmen. Such was Basil, who, having accompanied his master to Greece, was adopted by a rich widow at Patras. Her wealth enabled him to purchase large estates in Macedonia, whence he derived his surname Macedo, unless it be true that it was given him on account of his pretended descent, on his mother's side, either from Alexander the Great or his father, Philip of Macedonia, which however seems to be little better than a fable. He continued to attend the little Theophilus, and after the accession of Michael III. in 842, attracted the attention of this emperor by vanquishing in single combat a giant Bulgarian, who was reputed to be the first pugilist of his time. In 854 Michael appointed him his chief chamberlain; and the ambition of Basil became so conspicuous, that the courtiers used to say that he was the lion who would devour them all. Basil was married to one Maria, by whom he had a son, Constantine; but, in order to make his fortune, he repudiated his wife, and married Eudoxia Ingerina, the concubine of the emperor, who took in exchange Thecla, the sister of Basil. The marriage was celebrated in December, 865; and in September, 866, Ingerina became the mother of Leo, afterwards emperor. The influence of Basil increased daily, and he was daring enough to form a conspiracy against the emperor's uncle, Bardus, upon whom the dignity of Caesar had been conferred, and who was assassinated in the presence of Michael.

A short time afterwards, Basil was created Augustus, and the administration of the empire devolved upon him, Michael being unable to conduct it on account of his drunkenness and other vices. The emperor became nevertheless jealous of his associate, and resolved upon his ruin; but he was prevented front carrying his plan into execution by the bold energy of Basil, by whose contrivance Michael was murdered after a debauch on the 24th of September, 867.

Basil, who succeeded him on the throne, was no general, but a bold, active man, whose intelligence was of a superior kind, though his character was stained with many a vice, which he had learned during the time of his slavery among the barbarians and of his courtiership at Constantinople. The famous patriarch Photius having caused those religious troubles for which his name is so conspicuous in ecclesiastical and political history, Basil instantly removed him from the see of Constantinople, and put Ignatius in his place. He likewise ordered a campaign to be undertaken against the warlike sect of the Paulicians, whom his generals brought to obedience. A still greater danger arose from the Arabs, who, during the reign of the incompetent Michael III., had made great progress in Asia and Europe. Basil, who knew how to choose good generals, forced the Arabs to renounce the siege of Ragusa. In 872, he accompanied his Asiatic army, which crossed the Euphrates and defeated the Arabs in many engagements, especially in Cilicia in 875. In 877 the patriarch Ignatius died, and Photins succeeded in resuming his former dignity, under circumstances the narrative of which belongs to the life of PHOTIUS. The success which the Greek arms had obtained against the Arabs, encouraged Basil to form the plan of driving them out of Italy, the southern part of which, as well as Sicily and Syracuse, they had gradually conquered during the ninth century. They had also laid siege to Chalcis; but there they were defeated with great loss, and the Greeks burnt the greater part of their fleet off Creta. After these successes, Basil sent an army to Italy, which was commanded by Procopius and his lieutenant Leo. Procopius defeated the Arabs wherever he met them; but his glory excited the jealousy of Leo, who abandoned Procopius in the heat of a general action. Procopius was killed while endeavouring to rouse the spirit of his soldiers, who hesitated when they beheld the defection of Leo. Notwithstanding these unfavourable occurrences, the Greeks carried the day. Basil immediately recalled Leo, who was mutilated and sent into exile. The new commander-in-chief of the Greek army in Italy was Stephanus Maxentius, an incompetent general, who was soon superseded in his command by Nicephorus Phocas, the grandfather of Nicephorus Phocas who became emperor in 963. This happened in 885; and in one campaign Nicephorus Phocas expelled the Arabs from the continent of Italy, and forced them to content themselves with Sicily.

About 879, Basil lost his eldest son, Constantine. His second son, Leo, who succeeded Basil as Leo VI. Philosophus, was for some time the favourite of his father, till one Santabaren succeeded in kindling jealousy between the emperor and his son. Leo was in danger of being put to death for crimes which he had never committed, when Basil discovered that he had been abused by a traitor. Santabaren was punished (885), and the good understanding between Basil and Leo was no more troubled. In the month of February, 886, Basil was wounded by a stag while hunting, and died in consequence of his wounds on the 1st of March of the same year.

Basil was one of the greatest emperors of the East; he was admired and respected by his subjects and the nations of Europe. The weak government of Michael III. had been universally despised, and the empire under him was on the brink of ruin, through external enemies and internal troubles. Basil left it to his son in a flourishing state, with a well organised administration, and increased by considerable conquests. As a legislator, Basil is known for having begun a new collection of the laws of the Eastern empire, the Βασιλικαὶ Διατάξεις, , or simply , which were finished by his son Leo, and afterwards augmented by Constantine Porphyrogeneta. The bibliographical history of this code belongs to the history of LEO VI. Philosophus. (See Dict. of Ant. s. v. Basilica.) The reign of Basil is likewise distinguished by the propagation of the Christian religion in Bulgaria, a most important event for the future history of the East.