The Tall Brothers were four brothers among the Egyptian monks of Nitria in the fifth century by the names of Ammonius, Dioscorus, Eusebius, and Euthymius. They were referred to as the "Tall Brothers" because they were tall in stature and demanding in appearance.
The Tall Brothers were opposed in Alexandria by Patriarch Theophilus (the uncle of the future Saint Cyril of Alexandria). Theophilus exploited the well-known Origenism of the Tall Brothers in order to have Saint John Chrysostom condemned at the Synod of the Oak in AD 403. Subsequently however, the Tall Brothers fled Alexandria and were received by Saint John Chrysostom, Patriarch of Constantinople.