Eustratius Garidas (Greek: Εὐστράτιος Γαριδᾶς), was Patriarch of Constantinople between 1081 and 1084. He was a eunuch and uneducated. Due to his illiteracy he was involved in the case of John Italus, whom his predecessor, Patriarch Cosmas I of Constantinople had condemned. His involvement in this case cost him the throne in July 1084.