Mizizios (Greek: Μιζίζιος; Armenian: Մժէժ, Mžēž or Mzhezh) was an Armenian noble who served as a general of Byzantium, later usurping the Byzantine throne in Sicily from 668 to 669.
Mizizios accompanied Emperor Constans II in his Italian and Sicilian expedition. When Constans was murdered in Syracuse, Sicily, in 668, Mizizios was proclaimed emperor against his will. However, according to the supposed letter of Pope Gregory II, the Sicilian bishops had pushed him to rebellion, because Constans had been a heretic for his support of Monothelitism.
Michael the Syrian implies that the rebellion lasted about seven months before it was suppressed, but the sources, and modern scholars, are divided in how that came about: Theophanes the Confessor reports that Constans' son, Constantine IV, personally led an expedition to Sicily, where he had Mizizios and his father's murderers executed, while the Liber pontificalis reports that loyalist troops from Italy and the Exarchate of Africa suppressed the revolt, executed Mizizios, and sent his severed head to Constantinople.