Aristocracy is a form of government, in which a few of the most prominent citizens rule. This may be a hereditary elite, or it may be by a system of cooption where a council of prominent citizens and leading soldiers, merchants, land owners, priests, and lawyers to their number. This form of government was used commonly in ancient Greece, as well as monarchy, oligarchy, tyranny, and democracy in Athens.

Aristocracies have most often been hereditary plutocracies. They sometimes include a monarch who although a member of the aristocracy, rules over it as well as over the rest of society. The term "aristocracy" is derived from the Greek language aristokratia, meaning 'the rule of the best'. See Aristocracy for the historical roots of the term.