Caesar is a title used for a Roman emperor from about 30 B.C. to A.D. 70--derived from the line of Julian. There were several Caesars: Tiberius, Caligula, Claudius I, and Nero. The word then became the title to designate the Ruler of the Roman Empire. References to Caesar in the Bible can be found in Matt. 22:17, Luke 2:1, John 19:12, Acts 25:11-12, etc.