Doc Savage #16 (Bantam Books, 1967)

Doc Savage fades from sight as he uncovers the secret behind the "Spook Legion" and their use of invisibility to commit crimes and evade capture. This stunning paperback cover is a prime example of how artist James Bama redefined the Man of Bronze for the 1960s and beyond -- deepening the tone of his bronze skin, giving him an exaggerated widows peak, and dressing him in ripped shirts over his ripped physique, moving him away from the established "heroic man" of 1930s pulps to the larger-than-life superhuman he's known as now.