What is rule by one person called?

Rule by one person is called a monarchy or an autocracy, depending on how the power is held:

1. Monarchy

A form of government where one person, usually a king or queen, rules.

Power is often inherited through a royal family.

Can be:

Absolute monarchy – the monarch has complete power (e.g., historical Saudi Arabia).

Constitutional monarchy – the monarch’s power is limited by laws or a constitution (e.g., the UK, Japan).

2. Autocracy

A broader term for rule by one person with absolute power.

The ruler is not restricted by laws or constitutions.

Common in dictatorships, where the leader may seize power by force (e.g., North Korea).

So:

If the ruler inherits the position → Monarchy.

If the ruler takes or holds power without legal limits → Autocracy or Dictatorship.