It would be an "absolute monarchy" that gives all power to one individual for life, since this person usually gains power either through hereditary succession of through violence.
Absolute monarchy is a form of government in which the king has absolute power. In it there is no division of powers (executive, legislative and judicial). Although the administration of justice may have a relative autonomy in relation to the king, or there may be parliamentary institutions, the absolute monarch may change the decisions or rulings of the courts in the last resort or reform the laws at his will (The word of the king is law ). Appoint and withdraw your assistants in government at your will. The unity of all powers is usually considered justified by estimating that the source of power is God and that monarchs exercise sovereignty by divine right of kings. There are no mechanisms by which the sovereign (who does not recognize superiors) responds by his acts, if not before God himself.
The absolute monarchy is developed historically in Western Europe from the authoritarian monarchies that arise at the end of the Middle Ages with the crisis of feudal monarchies and the predominance that acquires the king in relation to all estates.
