A despot.
a person who rules by force
Dictatirship
A person who takes over a country by force and rules it is typically referred to as a dictator, autocrat, or tyrant. They often seize power through military force, coercion, or manipulation, leading to the suppression of democracy and individual freedoms within the country.
Authority is somebody who takes over control over other people or a group, by power and respect. Authority is all about the power through position. Like a lieutenant or a corporal. They are given these instructions or these commands so that they obey the government legislation for the police force, army etc. Authority is mostly all about the power to give the right orders and make the right decisions that may help others. It is also there to help enforce obedience, this may mean that you have a lot of authority over attendants. Authority is about the right to act, and you are given a delegated from one person to another.
insurgent: in opposition to a civil authority or government; a person who takes part in an armed rebellion against the constituted authority (especially in the hope of improving conditions); a member of an irregular armed force that fights a stronger
The person who takes power illegaly in Greece is the tyrant!
Born into power, marries into power, takes power by force.
dictatorship
a tyrant
a tyranny is when a person takes over by force
Usurper
A tyrant