Ammonius (/əˈmoʊniəs/; Greek: Ἀμμώνιος) was a Christian monk involved in the power struggle between the bishop Cyril of Alexandria and the Praefectus augustalis Orestes in the 5th century.
Ammonius was part of a group of supporters of the bishop Cyril, composed of both Parabalani and Nitrian monks.
Whether he was a member of the Parabalani or the Nitrian monks in support of Cyril during his early reign is not made clear.
[citation needed] He, along with his fellow monks, confronted the Prefect riding in his open chariot in the streets of Alexandria.
This title was soon stripped by Cyril after fellow Christians who were embarrassed by his actions began to question this decision.