Roman dictator
One of the most well-known incidents of a republican leader extending his term indefinitely was Roman dictator Julius Caesar, who made himself "Perpetual Dictator" in 45 BC. Traditionally, the office of dictator could only be held for six months, and although he was not the first Roman dictator to be given the office with no term limit, it was Caesar's dictatorship that inspired the string of Roman emperors who ruled after his assassination.