What type of government is characterized by a single ruler with absolute power?

The type of government characterized by a single ruler with absolute power is known as a monarchy. In a monarchy, the authority rests with one individual, typically a king or queen, who usually inherits their position. This ruler has the power to make decisions without the need for consent from others, which distinguishes it from other forms of government.

Monarchies can be absolute or constitutional. In an absolute monarchy, the monarch wields unrestricted powers over the state and its people, often claiming divine or hereditary rights. This concentration of power in the hands of one individual allows them to enact laws, levy taxes, and govern without the checks and balances present in democracies or other governmental structures.

This contrasts sharply with a democracy, where power is distributed among the population and government officials are elected by the citizens. Similarly, an oligarchy is characterized by power residing with a small group of individuals, while anarchy refers to the absence or lack of government, where no single authority is recognized. Thus, monarchy aptly fits the definition provided in the question.