Viceroy

A viceroy is somebody who governs a country or province as a substitute for the monarch. The term derives from the words vice and royal. A viceroy's wife is called a vicereine.

For example when Spain controled much of the New World, communications with the mother country could take months, so the King of Spain appointed Viceroys in Mexico City to govern New Spain and in Lima, Peru to govern western South America. One of the most famous and powerful viceroy offices in the world was the Viceroy of India during the British Raj.