Diocletian (died 316): Roman Emperor 284-305. Born around 256, he took over the Empire after a long period of instability. To simplify the administration of the Empire, he divided it into two halves, each in turn divided in half, with an Augustus ruling each half and two Caesars to rule particular provinces. This worked well while Diocletian was in charge, but after he abdicated in 305, it all fell apart as the various contenders tried to take over the whole Empire. When the Empire was finally reunited by Constantine the Great, he turned the Empire Christian -- an ironic and probably bitter result for Diocletian, who had been a great persecutor of Christians.