1. 独裁者;专政者
A dictator is a ruler who has complete power in a country, especially power which was obtained by force and is used unfairly or cruelly.

noun

1. a person who behaves in a tyrannical manner

e.g. my boss is a dictator who makes everyone work overtime

Synonym: authoritarian

2. a ruler who is unconstrained by law

Synonym: potentate

3. a speaker who dictates to a secretary or a recording machine