Roman dictator

The dictator in ancient Rome was a magistracy of the cursus honorum which allowed a person to save the Roman state and having more power for up to six months. The roman senate chose a Master of the Horse(magister equitum) who could control the Dictator. The senate gave him a well defined task and some authority. He didn't get all the power although most of the people think he had. Originally, he was in charge of the infantry, but as time went on, culminating with the dictatorship of Sulla, the office became increasingly similar to modern dictatorships. After Caesar was killed and Augustus ascended the "throne", the dictatorship was virtually abolished and no one held the title in Rome afterwards.

P.S. The dictator was considered to be a normal magistrate and had not the sense of modern dictatorship which is known nowadays