[Beckwith]

During the 20th Century, the communists killed more people than anybody.

Stalin 25,000,000
Mao 60,000,000

They made Hitler and Mussolini and Saddam combined look like pikers.

[ValenB4]

You can't put Mussolini in the category of those killers. Compared to them, he was a saint. Communists are red for a reason.

[Question_Assumptions]

Of course for sheer percentages, it's difficult to beat Pol Pot and the Khmer Rouge. They managed to kill about a quarter to a third of Cambodia's entire population after they were given the green light to take over when the Democrats cut funding to the right-wing government fighting them and while the Left, including Noam Chomsky, cheered them on and made excuses for them.