What system of government is ruled by a single entity or leader?

The system of government ruled by a single entity or leader is known as an autocracy. In an autocracy, one individual holds significant power and authority, making decisions for the state without requiring consent from others. This leader can act unilaterally, which means they can enforce laws, make policies, and govern the populace without the involvement or approval of a legislative body.

Autocracies can manifest in various forms, such as absolute monarchies where a king or queen rules with total authority, or dictatorships where a single leader exercises comprehensive control, often maintained through coercive means. The key characteristic of an autocracy is that it centralizes power in one person, contrasting sharply with systems like democracy, where power is distributed among the populace through elected representatives, and oligarchy, which involves a small group of individuals wielding power. In theocracy, power is held by religious leaders or institutions, drawing authority from religious texts rather than from an individual leader.