Flavius Rufinus (died November 27, 395) was a 4th-century Eastern Roman Empire statesman of Gaulish extraction who served as Praetorian prefect of the East for the emperor Theodosius I, as well as his son Arcadius, under whom Rufinus was the actual power behind the throne.
He was the subject of the verse invective In Rufinum by the western court poet Claudian.
Tall and always in movement, he is described as acute, ambitious, greedy and without principles, but a rigorous Christian. His difficulty with the Greek language is recorded by the sources, as well as his Aquitanian origin.
In 388 he was appointed magister officiorum. In 392 he served as Roman consul and in that same year he was appointed as Praetorian prefect of the East. Emperor Theodosius trusted Rufinus, and he used this influence to fight his opponents at the court. He came into conflict with Promotus and Timasius, respectively magister equitum and magister peditum of Theodosius. During a meeting of the council, Rufinus insulted Promotus, who slapped him; Rufinus went to Theodosius to report the affront, and Theodosius replied that if nothing changed he would have appointed Rufinus co-emperor. Taking advantage of the imperial support, Rufinus suggested Theodosius send Promotus to Thrace, where he would be entrusted with the training of the troops. Some barbarians followed Promotus in his travel, but, having an agreement with Rufinus, they suddenly attacked and killed Promotus (September 392).