Possibly the Best Origin Story of Marvel's Silver Age
Of all the initial Marvel superheroes, the one that I always found to be most believable (and still do), is Iron Man. The weird radiation side effects of the Hulk, Spider-Man, and the Fantastic Four just seemed to implausible, and Thor and Dr. Strange were pretty much just magic based characters. While he might not have been the most relate-able character, given that he was a handsome millionaire inventor, he was, as initially conceive, to my mind at least, the most plausible. A military scientist who (with help) creates a suit of powered armor that both keeps him alive and protects him from harm. He's a self-made hero, kind of like Batman that way.
So it's not surprising that Iron Man's first appearance in Tales of Suspense #39 hold up pretty well today. In fact, the essential origin story of Iron Man needed very little updating when it was made into a feature film in in 2008 - 45 years after the story first saw print! Some of the credit - perhaps much of it - is owed to one of the unsung heroes of Marvel's early days, Larry Lieber. Stan Lee may have had some great ideas, but as I've pointed out in the past, his dialogue scripts often left a lot to be desired. By Stan plotting this, and then handing the scripting chores off to Larry, we get the best of both their talents, and Don Heck's pencils while not as unique as Jack Kirby's, were stronger than Steve Ditko's, which all adds up to one of the real gems of Marvel's Silver Age.
Reading Tales of Suspense #39 is more rewarding than just the nostalgia factor - it's still a good story.