Action Comics #407

Behind the bars of what appears to be a cage, Superman tears open his shirt to reveal the famous "S" shield — visibly torn between protecting his Clark Kent identity and saving a man and his son who stand at gunpoint from a green-hooded villain in the foreground. Cover artists Curt Swan and Murphy Anderson bring real tension to the scene, with Superman's anguished speech bubbles laying the stakes bare: his secret identity may be the price of heroism. This 48-page December 1971 issue leads with "The Fiend in the Fortress of Solitude," a story that puts Superman's most closely guarded secret squarely in the crosshairs.