There are pretty damn evil people who have lived on this planet. Just to clarify, I'm limiting this list to people who were around a long time ago. I'm not going to include anyone who was in recent history and included World War II, so no Nazis here because they would just fill up the whole list and then some.
1 Elizabeth Bathory
Who was the most twisted serial killer of all time? This bitch was. And yes, that term is completely justified in describing this Countess who lived in the Carpathian Mountains. You see, she was convinced that if she bathed in the blood of young girls it would rejuvenate her and allow to live forever. So she murdered and tortured somewhere around 650 girls often by stabbing them with needles and burning every body part you can imagine. Most of them died from starvation or other horrible methods. And the worst part is that she was never put on trial for her crimes. Instead she died of natural causes. Obviously bathing in blood didn't do what she thought it would. However she lives on in part as she was one of the inspirations for Dracula.
2 Maximilien Robespierre
Robespierre started off with good intentions. As the leader of the French Revolution he wanted the people of France to have the freedom and rights they deserved. But everything changed when he gained power. The Reign of Terror was a ten month period where he had mass executions carried out with the guillotine. He became so paranoid he would have people killed for any reason he could find because he was terrified of losing his power. Most executions were performed without a trial. An estimated 40,000 people were killed, including King Louis XVI and Queen Marie Antoinette. But justice was dished out when Robespierre himself was guillotined without trial.
Caligula was the third emperor of Rome from the years 37 to 41. Early in his reign he was afflicted by a "brain fever" that caused him to become mentally ill. Believing he was a god, Caligula went about torturing anyone he felt was an enemy. And that was anyone, even small children weren't safe from him. Parents were forced to watch their children being killed. His favorite thing to do was to saw people in half, starting from the crotch and working his way up to the head. His sexual perversion was also well documented. He would have orgies at this palace that included everybody and everything. Animals too. He was finally killed in the year 41.
4 Attila the Hun
This guy lead his army all across Europe and is credited with the downfall of the Roman Empire. How destructive was he? Well his nickname was the Scourge of God. He had no mercy and killed anyone in his path which included several hundred thousand people. No one is sure what caused his death, but one day he started coughing up blood and that was it for him.
Genghis Khan had a talent for killing people and he made good use of it. As ruler of the Mongolian Empire from 1206 to 1227, he conquered most of China and everything around the Caspian Sea. In all the battles that he lead his army into, it's estimated that he killed 20 to 60 million people which would account for 10% to 30% of the world's population at the time. He died of natural causes in 1227. KHANNNNNNNN!
6Tomas de Torquemada
This asshole was the Grand Inquisitor of Spain. Yep, the Spanish Inquisition was this guy. He ordered Jews and other non-Catholics to death for being heretics. His spies turned friends and family against each other as he fervently searched for anyone he thought was an enemy of the Catholic Church. People were tortured in all sorts of ways such as having their limbs ripped from their sockets, being burned alive or drowned. He's responsible for the deaths of over 30,000 people in some of the worst ways imaginable. Ironically there's a good chance he was part Jewish himself. Like so many other people on this list he died of old age instead of facing justice. But if there is a hell, that's where he is now.
7 Ivan the Terrible
Ivan was the ruler of Russia from 1533 to 1584. As a young child he took great pleasure in throwing animals to their deaths off of tall buildings. That's one of the signs of a future serial killer by the way. And since he was the Tsar of Russia his sadism was felt by everyone. He enjoyed torture, death and pain so much he would watch nearly every execution he ordered letting them drag on for hours so he could get off as much as he could from the suffering of his victim. Execution methods included beheading, strangling, hanging, burning, stabbing, boiling, disembowelment, being buried alive, impalement and being fried. Yeah, fried to death. He would destroy entire villages just because he could. He killed anyone who questioned him, including his wife and son. He died while playing chess one day. It's thought that he was poisoned.
Another Roman emperor, Nero was the 5th supreme ruler of Rome and he drove it right into the ground. He burned entire cities and murdered just about every member of his family just because he could. He was so damn evil that many Christians thought he was the Antichrist. He was the one had the apostle Paul and his disciple Peter tortured and killed. The expression "Nero fiddled while Rome burned" is of course about this guy. Finally the people rose up and Nero committed suicide when he realized he was about to lose power.
10 Vlad Dracula
And now we have this dude, the prince of Wallachia. Vlad the Impaler is the inspiration for Dracula himself. Dracula literally means the devil, or the dragon depending on how you translate it. He's well known for impaling people since it was his favorite method of killing people. He made sure that each stake he used was well oiled and not too sharp since he didn't want to kill the person right away. The stake was then inserted from one end until it came out through the other. I'm sure you can figure what that must have looked like. He hated anyone he saw as being sick or weak and would burn alive anyone who offended him. It's said that he killed 100,000 people which would be 20% of the population of Wallacha. And yes, it was said he enjoyed drinking blood. He was finally decapitated in 1476.