Michael II (Greek: Μιχαήλ Β'), surnamed the Amorian (ὁ ἐξ Ἀμορίου) or the Stammerer (ὁ Τραυλός or ὁ Ψελλός), reigned as Byzantine Emperor from 25 December 820 to his death on 2 October 829, the first ruler of the Phrygian or Amorian dynasty.
Born in Amorium, Michael was a soldier, rising to high rank along with his colleague Leo V the Armenian (r. 813–820). He helped Leo overthrow and take the place of Emperor Michael I Rangabe. However, they later had a falling out, and Leo sentenced Michael to death. Michael then masterminded a conspiracy which resulted in Leo's assassination on Christmas 820. Immediately he faced the long revolt of Thomas the Slav, which almost cost him his throne and was not completely suppressed until spring 824. The later years of his reign were marked by two major military disasters that had long-term effects: the beginning of the Muslim conquest of Sicily, and the loss of Crete to the Saracens. Domestically, he supported and strengthened the resumption of official iconoclasm, which had begun again under Leo V.