A Minister is a diplomat accredited by one sovereign state to another who ranks immediately below the ambassador and usually acts as his or her assistant.

A Minister Plenipotentiary (usually just referred to as a Minister) is a diplomatic representative with plenipotentiary powers (i.e. full authority to represent the ruler of his state), but ranking below an ambassador. At one time (until well into the 20th century), full ambassadors were only sent by powerful states to other powerful states and most diplomatic representatives to and from less powerful states were Ministers Plenipotentiary.