 Issue #4 (May 1962) reintroduced Namor the Sub-Mariner, an aquatic antihero who was a star character of Marvel's earliest iteration, Timely Comics, during the late 1930s and 1940s period that historians and fans call the Golden Age of Comics.Issue #5 (July 1962) introduced the team's most frequent nemesis, Doctor Doom.These earliest issues were published bimonthly.