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.

They were famous for their strict fasting, chastity, and knowledge of the Bible. They were controversial in that they were supporters of the contested theology of Origen of Alexandria.

The Tall Brothers were opposed in Alexandria by Patriarch Theophilus (the uncle of the future Saint Cyril of Alexandria). The Tall Brothers subsequently fled Alexandria and were received by Saint John Chrysostom, Patriarch of Constantinople

Patriarch of Constantinople

The Ecumenical Patriarch is the Archbishop of Constantinople – New Rome – ranking as primus inter pares in the Eastern Orthodox communion, which is seen by followers as the One, Holy, Catholic, and Apostolic Church....

. Theophilus exploited the well-known Origenism of the Tall Brothers in order to have Saint John Chrysostom condemned at the Synod of the Oak

Synod of the Oak

The Synod of the Oak was a provincial synod, held in Constantinople in July of 403, which condemned and deposed John Chrysostom as Patriarch of Constantinople....

in AD 403.