Overview
Marcus Flavius Valerius Constantius, also called Constantius I, was a Roman emperor from 305 to 306—and was father of Constantine the Great, the first Christian emperor of Rome. He was one of the four original members of the Tetrarchy established by Diocletian, first serving as caesar from 293 to 305 and then ruling as augustus until his death. The nickname "Chlorus" was first popularized by Byzantine-era historians and not used during the emperor's lifetime.