Gotta be Mao with the murder count.
Marx should get an assist for the other three, plus Pol Pot and Robert Mugabe.
This shouldn’t even be a question, right?
A key trait of Communism is to murder those who don’t want to be part of the collective, right?
Of course, they also murder many who DO want to be part of the collective, but could pose a threat.
And also murder many who are related to those they view as threats.
As well as many who might utter something that is perceived as a threat.
They murder people to set an example for others to toe the line Party Line.
They murder many who are inconvenient.
And they murder some simply because they enjoy murdering people under their control.
In that light, yeah. Mao is Number One!