Khilji was not the only cruel ruler in the history. Apart from him there were many other rulers who crossed all the boundaries of being an evil ruler and there was absolutely nothing since they ruled which could stop them from the destruction they caused to the world.
1. Maximilien Robespierre
Born in 1758 in France, Maximilien Robespierre was responsible for the killings of his own close family members. He saw everyone around him as enemies and envied each one of them. After the French Revolution, he got so obsessed with guillotining that he guillotined all the families of aristocrats and ordinary people without a miss. Karma repeated and he got his punishment in 1794 as he was guillotined without trial.
2. Attila the Hun
He ruled the Huns from 434 to 453 and has been known as one of the evilest rulers ever. Attila is responsible for invading Italy and causing heavy destruction along with devastation in the northern provinces there at that time..
3. Genghis Khan
A very common name, Genghis Khan which you must have listened several times in your life. He was the founder of the Mongol Empire which he created and built by uniting many of the nomadic tribes of northeast Asia. During his rule, he carried out several invasions which resulted in the conquest of most of Eurasia.
4. Tamerlane the Great (Timur)
The evil Turkic ruler, Timur believed that he was the descendant of Genghis Khan and was responsible for killing lakhs of people while creating towers with their skulls. He cruelly invaded India, and killed more than 1 lakh people even when some cities offered to unconditionally surrender during his rule.
5. Vlad the Impaler (Vlad Dracula)
Vlad III, Prince of Wallachia ruled in the period of 1456 to 1462 and was popular for his exceedingly brutal ways of punishments and torture. He was known for torturing thousands of people and also he ate and drunk among the corpses. It is said that he impaled nearly 20,000 men, women and children in the city of Amlas. He loved different kind of tortures which included burning, roasting, skinning, boiling, decapitation, blinding, burying alive, stabbing the people etc. He also liked to cut off noses, ears, sexual organs, and limbs.