1 Nazi Germany
By far the worst! Murderer!
2 Empire of Japan
The worst Murderer ever!
3 Mongol Empire
Yea it was brutal but I don't think it deserves to be on the list. Genghis Khan was a military and tactical genius and the empire itself was fair to its people and allies
Killed the greatest-ever percentage of the world's population of any civilization in history.
4 French Empire
5 French State
6 British Empire
7 Confederate States of America
Terrible group, but it should be noted that every other name on this list also held slaves, and even many countries like Spain, Portugal, and Netherlands had them in their colonies even longer than the Confederate states did.
9 Ottoman Empire
10 Soviet Union
11 People's Republic of China
China, officially the People's Republic of China, is a country in East Asia. It is the world's most populous country, with a population of more than 1.4 billion. China spans five geographical time zones and borders 14 countries, the second most of any country in the world after Russia. Covering an area of approximately 9.6 million square kilometers (3,700,000 sq mi), it is the world's third or fourth largest country. The country consists of 23 provinces, five autonomous regions, four municipalities, and two Special Administrative Regions (Hong Kong and Macau). The national capital is Beijing, and the most populous city and financial center is Shanghai. Chinese (Mandarin) is the only official language and major languages. Cantonese is a common dialect used in Hong Kong and Macau (but the people there don't think it is a dialect). Ancient China invented paper, silk, gunpowder, and many things we rely on today.
Killed 60 million of their own civilians in the Cultural Revolution.