Flavianus was a Roman civil official who served as governor or prefect of Egypt (Latin: praefectus Aegypti) from 364 to 366. He was a native of Illyricum, the only one since the emperor Constantine I to hold the office. Flavianus was apparently already serving in some administrative capacity in Egypt, perhaps as Latin: praeses, before succeeding Maximus as prefect in 364. On 5 May 365 he received from the emperor Valens an edict on banished bishops, and on 8 June he sent the emperor a report seeking instructions on how to deal with the trinitarian bishop Athanasius. On 5 October 365, Flavianus, alongside the Latin: dux Victorinus, tried to arrest Athanasius, who escaped. On 1 February 366, he was instructed, through the notary Brasidas, to desist and allow Athanasius to return. Flavianus was succeeded as prefect after 21 July by Proclianus.
. 1971 . J.R. Martindale . J. Morris . Flavianus 3 . 343 . [{{googlebooks|uOHw4idqAeYC|plainurl=y}} The Prosopography of the Later Roman Empire Volume 1: A.D. 260–395 ]. Cambridge University Press . 0-521-07233-6 . amp . A. H. M. Jones . John Robert Martindale . John Morris (historian) . .