The Peacetime Peace Dictionary
A Tyrant is an individual who is given (or who has taken for themselves by force) a power over the lives of others. A tyranny usually requires a police state or military state.
Such all embracing power is inevitably misused or abused. A tyrant can bring upon themselves and their country great suffering and misery.
(The examples of Napoleon Bonaparte and France: Adolf Hitler and Germany).
Anti-tyranny policies tend to involve - Human Rights; Written Democratic Constitutions and The Rule of Law, based on custom.