Was Zero Mostel ever a communist?

Answer 1

He was accused of it, as were many other entertainers during the McCarthy era. However, the truth is more difficult to discern. There was little credible evidence that he was an actual member of the Communist party. But there was strong evidence that he had performed for some groups that were aligned with the Communist Party and he had also participated in causes that McCarthy and other conservatives considered too "left-wing."

Mostel believed that the United States treated the poor unfairly, and he supported groups that, in his view, were fighting for economic justice; among those groups were several that the House UnAmerican Activities Committee (HUAC) regarded as Communist fronts. Whether Mostel shared Communist views is difficult to say, but he did agree that America needed to be more egalitarian. Such political views were enough to have the HUAC accuse him of being a Communist sympathizer, putting the brakes on what had up to that point been a very successful career.