Virius Nicomachus Flavianus (334–394 AD) was a grammarian, a historian and a politician of the Roman Empire.
A pagan and close friend of Quintus Aurelius Symmachus, he was Praetorian prefect of Italy in 390–392. Under the usurper Eugenius (392–394), Flavianus was again praetorian prefect (393–394) and consul (394, recognized only within Eugenius' territory). After the death of Eugenius in the battle of the Frigidus, Flavianus killed himself.