Autocracy is a system of government in which absolute power over a state is concentrated in the hands of one person, whose decisions are subject neither to external legal restraints nor to regularized mechanisms of popular control (except perhaps for the implicit threat of a coup d'état or other forms of rebellion).

In earlier times, the term autocrat was coined as a favorable description of a ruler, having some connection to the concept of "lack of conflicts of interests" as well as an indication of grandeur and power. This use of the term continued into modern times, as the Russian emperor was styled "Autocrat of all the Russias" as late as the early 20th century. In the 19th century, Eastern and Central Europe were under autocratic monarchies within the territories of which lived diverse peoples.

Autocracy is the most common and durable regime type since the emergence of the state.