Dictator is originally the title of a magistrate in ancient Rome appointed by the Roman Senate|Senate to rule the state in times of emergency. In modern usage, it refers to an absolutist or autocratic ruler who assumes sole power over the state (though the term is normally not applied to an absolute monarch). Like the term tyrant, and to a lesser degree autocrat, it was a respectable title in the ancient world, but has some come to be used almost exclusively as a non-titular term for oppressive, even abusive, despot who rules with no regard for any existing democratic structures, organs or other entities. Almost always marked by a resilient resistance to reality and rational thought. This enables the dictator to act in a manner otherwise impossible. As such, grave human rights violations, torture, disappearances, pervasive surveillance and the repeal of existing human rights laws, become the norm in societies ruled by dictators. Summary execution is the punishment of choice for a wide variety of offenses, both criminal and political, under the rule of a dictator.
Dictators come to power in a variety of ways. They can be elected fairly and then refuse to give up power; they may seize control of the country in a coup d'etat; or they may be placed in power as the puppet of a stronger country that desires influence in the region. Alternatively, some countries such as the former Soviet Union are ruled by a single party which appoints a succession of dictators without regard for its people; this is known as a systemic dictatorship.
Since the nature of dictatorship is fundamentally at odds with the principals of democracy, dictators are usually condemned by the international community. Consequently, many adopt tactics to try and give their regime an air of legitimacy, such as holding sham or coerced elections, or declaring a state of emergency in the country with the implication that democracy will be restored in due course (almost always an empty promise).
Notable dictators in world history have included Adolf Hitler, Chancellor of Germany from 1933-45, Josef Stalin, General Secretary of the Communist Party of the Soviet Union from 1928-53, Pol Pot, head of the Khmer Rouge and ruler of Cambodia (or Kampuchea) from 1963-98, Mao Tzedong, ruler of China from 1945-76, and Islam Karimov, current ruler of Uzbekistan since 1991, Kim Jong Il of North Korea, and Muamar Ghaddafi, long-time terrorist leader of Libya.
Some rulers take on the traits of a dictator but have failed to secure totalitarian rule. Examples include Fidel Castro of Cuba.