Faustus of Riez was a 5th-century bishop in Southern Gaul and a prominent theologian. Born in Britain, he initially studied elocution and philosophy before entering the monastery of Lérins. After serving as an abbot for several decades, he was appointed Bishop of Riez in 432. He is most recognized for his theological efforts to combat Pelagianism and Arianism, often emphasizing the necessity of divine grace in human actions. His views on the relationship between grace and free will contributed to the development of what is sometimes called Semipelagianism.