Michael III (Greek: Μιχαήλ Γʹ) was Byzantine Emperor from 842 to 867. Michael III was the third and traditionally last member of the Amorian (or Phrygian) dynasty. He was given the disparaging epithet the Drunkard (ὁ Μέθυσος) by the hostile historians of the succeeding Macedonian dynasty, but modern historical research has rehabilitated his reputation to some extent, demonstrating the vital role his reign played in the resurgence of Byzantine power in the 9th century.
Michael was the youngest child of the emperor Theophilos and his empress Theodora. Already crowned co-ruler by his father in his infancy in 840, Michael had just turned two years old when his father died and Michael succeeded him as sole emperor on January 20, 842.
Michael III's marriage with Eudokia Dekapolitissa was childless, but the emperor did not want to risk a scandal by attempting to marry his mistress Eudokia Ingerina, daughter of the Varangian (Norse) imperial guard Inger. The solution he chose was to have Ingerina marry his favorite courtier and chamberlain Basil the Macedonian. While Michael carried on his relationship with Ingerina, Basil was kept satisfied with the emperor's sister Thekla, whom her brother retrieved from a monastery. Basil gained increasing influence over Michael, and in April 866 he convinced the emperor that the Caesar Bardas was conspiring against him and was duly allowed to murder Bardas. Now without serious rivals, Basil was crowned co-emperor on 26 May 866 and was adopted by the much younger Michael III. This curious development may have been intended to legitimize the eventual succession to the throne of Eudokia Ingerina's son Leo, who was widely believed to be Michael's son.
If ensuring Leo's legitimacy had been Michael's plan, it backfired. Ostensibly troubled by the favour Michael was beginning to show to another courtier, named Basiliskianos, whom he threatened to raise as another co-emperor, Basil had Michael assassinated as he lay insensible in his bedchamber following a drinking bout in September 867.