Roman statesman, a brilliant orator and writer who was a leading opponent of Christianity.

Symmachus was the son of a consular family of great distinction and wealth. His oratorical ability brought him an illustrious official career culminating in the proconsulship of Africa in 373, the city prefecture at Rome in 383–384, and the consulship for 391. When the emperor Gratian (367–383), under the influence of the Christian bishop of Milan, St. Ambrose (Ambrose, Saint), ordered the Altar of Victory to be removed from the Senate House at Rome in 382, Symmachus, who was an earnest pagan, was appointed by the Senate to go to Milan to plead with the emperor to cancel this anti-pagan measure; but the mission was a failure. After Gratian's murder in 383, Symmachus renewed his plea to Valentinian II (375–392) to revoke Gratian's anti-pagan orders; largely owing to the opposition of St. Ambrose, however, he was again unsuccessful. Symmachus's “Third Relatio to the Emperor,” written on this topic, and St. Ambrose's two letters of opposition survive. Symmachus's oration De ara Victoriae was considered so brilliant that even after 19 years the poet Prudentius found it necessary to write a reply to it. The increasingly Christian character of Valentinian's court caused Symmachus to lose much of his influence; but when Magnus Maximus drove Valentinian from Italy in 387, Symmachus, who was regarded as the leader of the Senate, was appointed to offer the new emperor the Senate's congratulations on his elevation. When Theodosius I reconquered Italy for Valentinian in 388, Symmachus was forgiven and appointed consul for 391. Under the pagan rule of Eugenius and Arbogast in 392–394 he apparently regained some of his influence and survived under Honorius until 402. The details of Symmachus's career are known from an extant inscription, set up by his son.

Symmachus's orations have been lost, except for fragments of eight speeches, but 900 letters were published by his son, Quintus Fabius Memmius Symmachus, who edited them in imitation of the letters of Pliny the Younger, in 10 books—nine of private letters and one consisting of letters to the emperor. The last includes his 49 formal addresses, or relationes, to Valentinian II while Symmachus was praefectus urbi. The standard critical edition of the Latin text is Q. Aurelii Symmachi Quae Supersunt (1883), edited by Otto Seeck. Symmachus's Relationes were translated in R.H. Barrow's Prefect and Emperor: The Relationes of Symmachus, AD 384 (1973).