I lol when people think Marx invented Communism.
He is the most widely cited proponent of collectivist / redistributionist economics. Whether he "invented communism" is a moot point. Without Marx and his ideas on the role of the state in economic matters it is entirely likely that there would have been no Bolshevik Revolution, no New Deal, no Iron Curatin, no Chinese "War of Liberation", etc. Credit for the genesis of the concepts is unimportant; but Marx's mark on the history of at least the 20th Century is indelible.