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Qin Shi Huang (259–210 BCE) -

Founder of the Qin dynasty and the first emperor of a unified China, Qin Shi Huang had a habit of dispatching scholars whose ideas he disagreed with. He's known for ordering a mausoleum guarded by life-sized terra-cotta soldier figures. After its completion, he had the workers killed to preserve the secrecy of the tomb.

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Caligula (12–41) -

Gaius Caesar Augustus Germanicus, better known as Caligula, began his reign as a noble and moderate emperor. However, after nearly dying of a mysterious illness, he became an insane tyrant notorious for cruelty, sadism, extravagance, and perversion.

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Attila the Hun (c. 406–453) -

Leader of the Hunnic Empire, which encompassed Central and Eastern Europe, Attila was one of the most feared antagonists of the Roman Empire. Possessing a commanding presence, his name became synonymous with battlefield know-how, and terror!

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Wu Zetian (624–705) -

Notable for being the only female monarch in the history of China, Wu Zetian was not known for sparing enemies. She was regarded as ruthless in her endeavors to grab power, and thought nothing of eliminating opponents either by dismissal, exile, or execution.

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Genghis Khan (c. 1158 –1227) -

Founder and first Great Khan (Emperor) of the Mongol Empire, Genghis Khan's reputation as the greatest conqueror of all time is somewhat diminished by his propensity for slaughtering civilians en masse. He was not adverse to using opponents as human shields in battle, and his brutality left millions dead.

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Timur (1336–1405) -

Historically known as Tamerlane, Timur, founder of the Timurid Empire, had a reputation as a merciless warlord with a nasty habit of encasing the body parts of slain opponents in the walls of towers and minarets.

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Tomás de Torquemada (1420–1498) -

Appointed the first Grand Inquisitor during the Spanish Inquisition, Torquemada was responsible for approximately 20,000 people burning at the stake. His name remains synonymous with cruelty, religious intolerance, and fanaticism.

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Vlad III (1428/31–1476/77) -

Infamous as Vlad the Impaler, Vlad III, ruler of the principality of Wallachia (present-day Romania), had a penchant for stabbing and impaling those he didn't like. His name and reputation for cruelty inspired the name of the vampire Count Dracula.

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Queen Mary I (1516–1558) -

Mary I became queen of England in 1553. Her vigorous attempt to reverse the English Reformation and reinstall Catholicism resulted in hundreds of Protestants and other religious dissenters being burned at the stake, for which she earned the sinister sobriquet "Bloody Mary."

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Ivan the Terrible (1530–1584) -

The first Czar of Russia, Ivan IV was prone to paranoia, rages, and episodic outbreaks of mental instability. It's believed he killed his son and beat his pregnant daughter-in-law in a fit of rage. It was during a prolonged reign of terror, when he violently repressed Russian aristocracy and later attacked Novgorod, that he earned the nickname "Ivan the Terrible."

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Tokugawa Ieyasu (1543–1616) -

History records Tokugawa Ieyasu as one of the great unifiers of Japan. He was the founder and first shogun of Japan’s Tokugawa shogunate, but his rise to power was littered with a high body count. Opponents were swiftly put to the sword, including family members who fell out of line.

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Elizabeth Báthory (1560–1614) -

Hungarian noblewoman Countess Elizabeth Báthory de Ecsed has been labeled by Guinness World Records as the most prolific female murderer in history. Accused of killing hundreds of young girls and women between 1590 and 1610, the final body count is said to be 650 dead.

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Oliver Cromwell (1599–1658) -

English general and statesman Oliver Cromwell led the Roundheads to victory over the Royalists in the English Civil War, and was one of the signatories of King Charles I's death warrant in 1649. He ruled the British Isles as Lord Protector, but was regarded as a regicidal military dictator by many. The measures taken by him against Catholics, particularly in Scotland and Ireland, verged on near-genocidal.

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Maximilien Robespierre (1758–1794) -

French lawyer and statesmen Maximilien Robespierre played a key role in the French Revolution and the subsequent "Reign of Terror," when thousands met a bloody end under the guillotine.

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Leopold II (1835–1909) -

Founder and sole owner of the Congo Free State, a project he set up as his own "private colony," King Leopold II of Belgium extracted a fortune from the territory by forcing the Congolese into slave labor for ivory and rubber. Leopold's administration of the Congo was characterized by atrocities, including torture and murder. Millions more died of starvation and neglect.

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Ismail Enver Pasha (1881–1922) -

After becoming Minister of War of the Ottoman Empire in 1914, Enver Pasha bore part responsibility for the Armenian Genocide, the systematic mass murder and expulsion of ethnic Armenians carried out in Turkey that resulted in the deaths of some 1.5 million people.

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Vladimir Lenin (1870–1924) -

Though considered one of the most significant and influential figures of the 20th century, Lenin founded and led an authoritarian regime responsible for political repression and mass killings.

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Joseph Stalin (1878–1953) -

Stalin assumed leadership of the Soviet Union following Lenin's death in 1924. He presided over the famine of 1932–33, instigated the Great Purge, in which over a million were imprisoned and at least 700,000 executed between 1934 and 1939, and ordered the incarceration of countless others in the Gulags.

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Khorloogiin Choibalsan (1895–1952) -

Mongolian leader Khorloogiin Choibalsan was a great admirer of Joseph Stalin. As such, he oversaw Soviet-like purges in the 1930s that resulted in the deaths of an estimated 30,000 to 35,000 Mongolians. Most of the victims were Buddhist clergy, intelligentsia, political dissidents, and members of ethnic minorities.

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Adolf Hitler (1889–1945) -

Leader of the Nazi Party, Adolf Hitler was responsible for the deaths of millions of people. His virulent anti-Semitism and obsessive pursuit of Aryan supremacy fueled the murder of some six million Jews, along with other victims of the Holocaust.

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Benito Mussolini (1883–1945) -

Mussolini founded Italy's Fascist Party and inspired other totalitarian rulers, including Adolf Hitler and Spain's Francisco Franco. In 1936, he formed an alliance with Hitler and led his country into the Second World War with disastrous results.

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Francisco Franco (1892–1975) -

Spanish general Francisco Franco led the Nationalist forces in overthrowing the Second Spanish Republic during the Spanish Civil War, which resulted in at least 500,000 casualties. He later ruled over the country as dictator, a reign marked by both brutal repression and economic prosperity.

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Hideki Tojo (1884–1948) -

Hideki Tojo served as Prime Minister of Japan during most of the Second World War. As well as supporting preemptive attacks of the United States and its European allies, he presided over numerous war crimes, including the massacre and starvation of civilians and prisoners of war.

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Mao Zedong (1893–1976) -

In 1966, Chinese communist revolutionary and founding father of the People's Republic of China Mao Zedong initiated the Cultural Revolution, a program to remove "counter-revolutionary" elements in Chinese society. Tens of millions of people were persecuted during the Revolution, while the estimated number of deaths ranges from hundreds of thousands to millions.   

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Nicolae Ceaușescu (1918–1989) -

Romanian communist politician and leader Nicolae Ceaușescu wielded an iron fist over a totalitarian government that oversaw mass surveillance as well as severe repression and human rights abuses within the country. Throughout the 1970s the regime was considered the most repressive in the Eastern Bloc.

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Pol Pot (1925–1998) -

Pol Pot was a political leader whose communist Khmer Rouge government led Cambodia from 1975 to 1979. During that time, an estimated 1.5 to 2 million Cambodians succumbed to starvation, disease, overwork, or execution in the notorious "killing fields." Many historians regard the Pol Pot regime as one of the most barbaric in recent history.

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Idi Amin (c. 1925–2003) -

Idi Amin was a Ugandan military officer who served as the President of Uganda from 1971 to 1979. His tenure was marked by the systematic persecution of certain ethnic groups and political dissidents, rampant human rights abuses, and extrajudicial killings. International observers and human rights groups estimate that between 100,000 and 500,000 people were killed under his regime, making Amin one of the most brutal despots in world history.

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Augusto Pinochet (1915–2006) -

After his rise to power, Chilean Army General Augusto Pinochet persecuted leftists, socialists, and political critics, resulting in the executions of up to 3,200 people. Many thousands more were tortured or simply "disappeared."

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Mobutu Sese Seko (1930–1997) -

Widespread human rights violations and unbridled economic exploitation and corruption characterized Zaire (now the Democratic Republic of the Congo) ruler Mobutu Sese Seko's presidency. Under his tenure, the nation also suffered from uncontrolled inflation, a large debt, and massive currency devaluations. Meanwhile, his personal fortune is estimated to have run into the millions.

Sources: (Guinness World Records) (History Collection) (Britannica)

See also: Who are the most infamous mobsters and gangsters?

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