Michael III (January 19, 840 – September 23/24, 867) is Byzantine Emperor from 842 to 867.

Michael III was the third and traditionally last member of the Amorian Dynasty, also known as the Phrygian Dynasty.

He is given the disparaging epithet the Drunkard 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.