An autocracy is a system of government in which supreme power is concentrated in the hands of one person, whose decisions are subject to neither external legal restraints nor regularized mechanisms of popular control (except perhaps for the implicit threat of a coup d'état or mass insurrection).Absolute monarchy (such as Saudi Arabia) and dictatorship (such as North Korea) are the main historical forms of autocracy. In very early times, the term "autocrat" was coined as a favorable feature of the ruler, having some connection to the concept of "lack of conflicts of interests".
In the Medieval Greek language, the term Autocrates was used for anyone holding the title emperor, regardless of the actual power of the monarch. Some historical Slavic monarchs, such as Russian tsars and emperors, included the title Autocrat as part of their official styles, distinguishing them from the constitutional monarchs elsewhere in Europe.
Both totalitarianism and military dictatorship are often identified with, but need not be, an autocracy. Totalitarianism is a system where the state strives to control every aspect of life and civil society. It can be headed by a supreme dictator, making it autocratic, but it can also have a collective leadership such as a commune, junta, or single political party.
In an analysis of militarized disputes between two states, if one of the states involved was an autocracy the chance of violence occurring doubled.
Because autocrats need a power structure to rule, it can be difficult to draw a clear line between historical autocracies and oligarchies. Most historical autocrats depended on their nobles, the military, the priesthood or other elite groups. Some autocracies are rationalized by assertion of divine right.