Hercules, the Prince of Power arrived at Marvel with some but not all that much fanfare. He debuted in the pages of Journey Into Mystery Annual #1, set up as counterpart to the established Thor. Since Marvel had already developed the Norse mythology it must have seemed beyond natural to do likewise for the Greco-Roman myths. And so we got Hercules, a handsome lunkhead who is all too willing to fight. Whereas Thor was a serious man who took on heavy responsibilities, despite the sometimes disdain of his father Odin, Hercules never seemed to fall into that trap. He wanted to enjoy his life and fill it with damsels, drink and when possible physical combat. He went on to become a near co-star with Thor in early issues of the run but after the story has run its course, Marvel still wanted to develop him and after a quick bout with the Hulk, he (like everyone eventually) joined the Mighty Avengers.
Herc was a member about the time I first encountered the Avengers and the Marvel magic, so I've always cottoned to him and the look he had at the time established by Don Heck and clearly inspired by the movie idol Steve Reeves. (My first Avengers was the battle between Herc and Namor and which I own a prized original page.) Hercules was an Avenger for a relatively short time but event drew him away and after that he was a bit lost. He turned up in a solo story sandwiched between to Ka-Zar reprints which was resolved in an issue Sub-Mariner after which he truly disappeared for quite some time, turning up in the Avengers again, just in time for the celebration of the hundredth issue. Hercules as it turns out, was the centerpiece of the story. He went on to co-star with Thor some more and later had some very significant runs in the Avengers and on his own, but these earliest adventures will always be my favorites.