Who knows why this action-packed Don Heck cover was not used for The Avengers #37 for February of 1967, since he did a colossal job on the interiors for this fan favorite Marvel title. Heck's professional career began in 1949 when he started working in the production department of Harvey Comics and studying art by mail order correspondence courses and junior college classes. Soon he graduated to penciling, and after a stint freelancing with Quality Comics, Hillman Comics and Toby Press. Heck then started at Atlas (Marvel) Comics on the recommendation of fellow artist Pete Morisi, becoming a mainstay, illustrating superhero, mystery, western, romance science fiction, fantasy, and war stories. When the House of Ideas began its Silver Age revolution, the artist's first major success was the legendary Iron Man origin story in Tales of Suspense #39 for March of 1963. He then drew a handful of early stories featuring the Mighty Thor, Giant Man and other heroes, but for most comic fans, it's Don's long run on The Avengers for which he is most fondly remembered. For some reason Gil Kane's exciting cover was chosen instead to grace this colossal issue, but it doesn't really matter, its just as terrific as the unpublished version in my opinion.