Marx doesn’t fit in to this group. All he did of consequence was write books. Stalin, Mao, and George W Bush all directly or indirectly ordered the murder of millions. Marx just wrote theory which only when misapplied by a violent state led to suffering. Marx never killed anyone!

It seems to me to be a gross intellectual error to conflate Marx with mass murderers. Marx’s theories were popular among revolutionaries at the time of Lenin’s rise and he took advantage of that appeal when he styled himself a Marxist. But even then he created his own theories we call Marxist-Leninism, so called because they are not based purely on Marx.

To say Marx played any real part in mass murder is like saying the Nasis were socialists because they put “socialist” in their name - intellectually vacant. I implore you - do not put so much stock in the writing of someone who has led you down this path! There are better answers out there without these gross errors.