Communism

The USSR signed a non-aggression pact after trying to get the Western Powers to help protect Czechoslovakia. The Western Powers of course denied this, as they wanted the Nazis to kill the Soviets. The Soviets ended up killing 80% of the Nazis that died in WWII, the scale of the Eastern Front was many times larger than the Western. Moreover, Americans and other western powers were ordered to not attack western business assets in Nazi Germany. This is because the West had ties to the Nazis, while the Communists and Nazis hated each others guts.

The Red Army saved the world from fascism, and paid the price with tens of millions of lives. They are heroes.