According to Aristotle's three classifications of government, if the government is ruled by one sovereign it is called a Monarchy, if this is corrupted to the selfish needs and ends of that one, it is called a Tyranny. If it is ruled by a few in society, who are above others it is called an aristocracy, however, if this is corrupted it is known as an Oligarchy, where this small group only seek selfish ends. If it is ruled by many for the good of all it is known as a Polity, or if it is for the good of many it is known as a democracy.
Rule by one: it is Monarchy or Tyranny (If Corrupted). Rule by Few: Aristocracy or Oligarchy (If corrupted) Rule by Many: Polity (For good of all) or Democracy (For the Good of many)