An autocracy is a form of government
Form of government
A form of government, or form of state governance, refers to the set of political institutions by which a government of a state is organized. Synonyms include "regime type" and "system of government".-Empirical and conceptual problems:...

 in which one person is the supreme power within the state. It is derived from the Greek : ("self") and ("rule"), and may be translated as "one who rules by himself". It is distinct from oligarchy
Oligarchy is a form of power structure in which power effectively rests with an elite class distinguished by royalty, wealth, family ties, commercial, and/or military legitimacy...

 ("rule by the few") and democracy
Democracy is generally defined as a form of government in which all adult citizens have an equal say in the decisions that affect their lives. Ideally, this includes equal participation in the proposal, development and passage of legislation into law...

 ("rule by the people"). Like "despot
Despotism is a form of government in which a single entity rules with absolute power. That entity may be an individual, as in an autocracy, or it may be a group, as in an oligarchy...

", "tyrant
A tyrant was originally one who illegally seized and controlled a governmental power in a polis. Tyrants were a group of individuals who took over many Greek poleis during the uprising of the middle classes in the sixth and seventh centuries BC, ousting the aristocratic governments.Plato and...

", "strongman" and "dictator
A dictator is a ruler who assumes sole and absolute power but without hereditary ascension such as an absolute monarch. When other states call the head of state of a particular state a dictator, that state is called a dictatorship...

", "autocrat" is a loaded word with a negative value judgment.
Autocracy and totalitarianism
Totalitarianism is a political system where the state recognizes no limits to its authority and strives to regulate every aspect of public and private life wherever feasible...

 are related concepts.