Prior to America's involvement in World War II, there were very few direct references to the Nazi party. Often analogues were used; many comics featured fictional European nations with vague regimes and strife which mirrored Germany in superficial ways, but usually were not direct parallels. The most famous exception was the first issue of Captain America Comics, which featured the title character punching Hitler in the face. The comic sold nearly a million copies and was popular with most readers, some parties took objection, with the comic company receiving hate mail, threats and, according to co-creator Joe Simon, menacing groups of people loitering in the halls. Following America's entry into the war, portrayals of fifth columnists and foreign powers as villains became explicitly Axis agents and enemies with iconic heroes fighting and denouncing them. One of the most notable superhero story arcs during the war, The Monster Society of Evil in Captain Marvel, featured Captain Marvel battling an evil organization that included Adolf Hitler, Benito Mussolini and Hideki Tojo, as well as Marvel's recurring Nazi enemies Captain Nazi and Herr Phoul. Throughout the war, Nazis became stock villains but by the Silver Age of the late 50s and early 60s, they were replaced by Communist threats (particularly in Marvel Comics in series such as The Hulk and Iron Man). Though Captain America would still face Nazi threats, most notably in his recurring enemy the Red Skull and HYDRA, the terrorist organization with Nazi origins, he too often faced more general international threats.