Theoktistos (; died November 20, 855) was an influential senior
Byzantine official during the reigns of
Michael II and his son
Theophilos, and the
de facto head of the
regency for the underage
Michael III from 842 until his dismissal and murder in 855. He is noted for his administrative and political competence, for ending the
Byzantine Iconoclasm, and for helping the ongoing renaissance in education within the Empire.