The term magistrate is used in a variety of systems of governments and laws to refer to a civilian officer who administers the law. In ancient Rome, a magistratus was one of the highest ranking government officers, and possessed both judicial and executive powers. In other parts of the world, such as China, magistrate is a word applied to a person responsible for administration over a particular geographic area. Today, in some jurisdictions, a magistrate is a judicial officer who hears cases in a lower court, and typically deals with more minor or preliminary matters. In other jurisdictions, magistrates are typically trained volunteers appointed to deal with criminal and civil matters in their local areas.

The Roman magistrates were elected officials in ancient Rome. During the period of the Roman Kingdom, the King of Rome was the principal executive magistrate. His power, in practice, was absolute. He was the chief priest, lawgiver, judge, and the sole commander of the army. When the king died, his power reverted to the Roman Senate, which then chose an Interrex to facilitate the election of a new king.