Tyrant, Greek tyrannos, a cruel and oppressive ruler or, in ancient Greece, a ruler who seized power unconstitutionally or inherited such power.
For the ancient Greeks, a tyrant was not necessarily a bad ruler; in its original form the word was used to describe a person who held absolute and personal power within a state, as distinct from a monarch, whose rule was bound by constitution and law.
Some tyrants were usurpers who came to power by their own efforts; others were elected to rule; and still others were imposed by intervention from outside. Later on in classical history, however, the word gradually acquired more of its modern meaning, implying a ruler whose sole motivation was power and personal gain, and as a result its use in public life became controversial.
All concepts and postulates of undemocratic power have always been based on the assumption that the authority and values of the rulers are something irresistible, because only this guarantees the stability of public order. The destruction of the order understood in such a way was invariably harmful. Therefore, if we are dealing with a reality that is assumed to be ideally rooted, then not only freedom is not recognized, but all manifestations of it are subject to ruthless extermination, because they are a threat to the order sustained by political power. Thus understood ideologies, the entire power of the state and its institutions was put into service
Throughout the history of mankind there have been many tyrants, dictators and cruel rulers that use terror to gain control of public. They ruled with an iron fist and an unrelenting thirst for power and recognition. Unfortunately for people there were too many of them to fit on the list, so here are the worst of the worst.