Who was Caesar? I've heard the name, but who is he, and when did he live? And were the others who also claimed to be Caesar?
Julius Caesar was a Roman general and statesman who lived 100-44 BC. His works (in easy-to-read language) are still read by Latin students to this day. When his associates in the Senate were alarmed by his growing, unfettered power, they assassinated him—on the Ides of March (the 15th), 44 BC.
In effect, although brilliant and efficient in many ways, Caesar was a dictator. No one likes to be pushed around, least of all other important persons. After the dust settled, his grandnephew Octavian became the first emperor, from 27 BC to AD 14. Beforehand, Julius Caesar adopted Octavian to be his son and heir—effectively his successor, in other words. Between these two men the empire became strong. Under Octavian's masterful leadership, an era of peace was ushered in, the Pax Romana, which greatly helped the fledgling Christian faith to spread quickly to every corner of the empire.
Octavian went by the title Caesar Augustus ("venerable" or "majestic"), and the following emperors too took Julius' family name Caesar—as a title. For example, there was Tiberius Caesar (14-37, emperor when Jesus was crucified), Gaius Caesar, called Caligula (37-41), and so on... (Claudius, Nero, Galba, Otho, Vitellius, Vespasian, Titus, Domitian, Nerva, and Trajan—to name only the caesars who came to power in the first century).