Aelia Flaccilla was a 4th-century Roman empress and the first wife of Emperor Theodosius I. Born in Hispania, she rose to the rank of Augusta following her husband's elevation to the throne. She was the mother of two future emperors, Arcadius and Honorius, as well as a daughter named Pulcheria. Throughout her life in the Byzantine Empire, she was recognized for her deep commitment to the Nicene faith and her dedication to charitable works in Constantinople.