If the early Avengers were the Beatles, then Henry Pym was Ringo. You had Thor, Iron Man, and the Hulk, all big strong bruisers who would become iconic characters in their own right. Even the Wasp, with powers Pym had given his then-girlfriend Janet Van Dyne, became a more prominent character. Pym, then in his Ant-Man identity (before Giant-Man, or Goliath, or Yellowjacket, or even his non-costumed "Dr. Pym" days with the West Coast Avengers), was a founding member of those Avengers. But he never thrived. Even as the world's foremost biochemist, his genius always paled next to Tony Stark. He was never the leader Captain America would be, or the roguish charmer like Hawkeye. It's like there was no place for him in the world's mightiest heroes, and so he kept changing himself and his powers, seeking the right formula, a quest that would eventually ruin his marriage to Janet and shatter his sanity.
But Pym never stopped trying. Here was a guy who abused his wife during his darkest days, betrayed the Avengers, and yet clawed his way back to heroism from the wilderness. It's important to note that of the early Marvel heroes, Pym was really the first to gain his powers intentionally. Mutants like the X-Men and gods like Thor were born that way, the Fantastic Four and Spider-Man and Hulk and Cap were victims of accidents that granted their powers or (in the case of Iron Man, Pym's closest analogue) misfortune that spurred their invention. But Pym set out to be a hero, and - this can't be emphasized enough - he discovered how to change the size of things, communicate with an animal species, and invented artificial intelligence (for those who are Marvel Cinematic Universe only and not the comics, Ultron was Pym's creation, not Stark's) . You want genius? Suck on that, Reed Richards. How this guy never parlayed that into Stark-esque billions, I'll never know.
Pym never gets the cred he deserves. Yeah, he hit Jan. He made Ultron. Like nobody ever makes mistakes. I still think he's one of the best, most unfairly ignored great characters in comic history. And Ringo was a great Beatle.