It's a complex issue. There have been a lot more communists than Nazis or Fascists (using the official Italian term) so that would tilt things a bit. But the fact remains that, not counting deaths in war, communist nations all together have been responsible for as many as 100 million deaths of their own citizens.

But you can still announce that you're a Marxist at the right cocktail parties and universities, and get approval. They might tell you that communism as practiced really has "nothing to do" with Marxism. That's a load of horseshit. All those communist governments and leaders proudly called themselves Marxist. And every Marxist society in history ended up as one of those ghastly oppressive communist nations. Not only looks and quacks like a duck, but has the exact same genome.