When you're dealing with a shared continuity comic book universe, you're bound to have characters whose histories end up being almost shockingly convoluted. That's just the nature of the beast, after all. However, you occasionally also see character transform by virtue of different creators taking control of them in ways that would never have been imaginable considering where they got their start. It's in that second group that Adam Warlock belongs, as Jim Starlin almost single-handedly transformed a minor hero into one of the greatest cosmic characters Marvel ever saw -- and soon, he'll a featured player in the "Guardians of the Galaxy" cinematic universe.
By 1965, the two most important artists at Marvel, Steve Ditko and Jack Kirby, were both displeased with how they were being handled by the company. Ditko asked for, and received, plotting credits on "Amazing Spider-Man," as he felt that it was unfair that he was coming up with the plots for the issues but was only being credit as the artist on the book. Soon after, Jack Kirby also ceased to be be credited as just the artist on "Fantastic Four," but rather just got a shared credit with Stan Lee, rather than writer/artist, it was just "Stan and Jack." However, like Ditko, by this point in time, Kirby was doing most of the plotting on the series, but unlike "Amazing Spider-Man," where Ditko refused to even communicate with Lee (basically, "Here's what I drew - go ahead and script it"), Lee had more freedom to alter the work that Kirby did on "Fantastic Four" (amusingly enough, decades later, the fact that Kirby wasn't paid for the pages that he would have to re-draw to match Lee's changes was a major argument in the case by Kirby's estate that Kirby wasn't actually working as a "work for hire" employee, but rather as a freelancer, as employees would typically be paid no matter what, while freelancers would be paid based on what was accepted by the company - so saving a few bucks in the 1960s later led to Marvel settling with the Kirby estate for millions). One of the stories that Lee drastically altered was the story of the Enclave, scientists who created the ultimate being. Kirby had envisioned them as a commentary on the concept of Objectivism, as he wanted the scientists to create a true Objectivist, but a true Objetivist wouldn't put up with the flaws in his creators, so he would end up destroying them. Lee, though, decided to make them generic evil scientists and that their creation destroyed them in "Fantastic Four" #67 for being evil...
This new "perfect" being (known as "Him") would be one of the last major characters that Kirby would create in "Fantastic Four," as Kirby began thinking more and more about leaving Marvel, and as a result, held off on introducing new characters while he was there, deciding instead to mostly use characters that he and Lee had already created. After "Him" made an appearance in "Thor" following his "Fantastic Four" debut, Roy Thomas and Gil Kane revamped "Him" into a new hero known as Adam Warlock for a new feature in "Marvel Premiere."
Inspired by the successful way that Andrew Lloyd Webber was able to do a new spin on Jesus Christ with "Jesus Christ Superstar," Thomas decided to turn Adam Warlock into a messiah-like character. He was even placed on a Counter-Earth (where he had to fight the Man-Beast, who was essentially a fallen angel like Lucifer) so that Thomas would have more freedom to explore the idea of a comics messiah.
The series did not last that long, just eight issues spread out over about a year. The character then went into character limbo. In stepped Jim Starlin, who had left a cosmic-based series called "Captain Marvel" due to a dispute with Marvel, but now that things had been settled, that series had already found a new creative team, so Starlin chose to bring Warlock back. Starlin brought the character back in the pages of "Strange Tales." Years later, Starlin would explain the route he chose to go with with the Warlock character, "I had basically taken Captain Marvel, a warrior, and turned him into sort of a messiah-type character. So when I got to Warlock, I said to myself, 'I got a messiah right here to start off with; where do I go from there?' And I decided a paranoid schizophrenic was the route to take."
In Starlin's run, he had Warlock deal with the an intergalactic church that was ruled by an evil version of Warlock himself from the future! This storyline allowed Starlin to explore the effects of religion in a fashion quite unusual for comic books of the era.
Starlin introduced a new supporting cast for Warlock, as well, in the person of two traveling companions for Warlock, an unruly troll named Pip and a dangerous assassin by the name of Gamora. Gamora, as it turned out, had been raised by Thanos, who Starlin had introduced years earlier in a fill-in issue of "Iron Man" and had become a major villain during Starlin's "Captain Marvel" series. Thanos soon became the main villain in "Warlock"...
While critically acclaimed, Starlin's take on "Warlock" was not a sales bonanza, and by the end of the 1970s, Starlin began to go work for DC Comics. Marvel's Editor-in-Chief at the time, Archie Goodwin, managed to convince Starlin to come back to Marvel and at least wrap up Warlock's story in two annuals. Starlin did so, but in a remarkable feat that really stood out for the time, he had Thanos kill Pip and Gamora and seemingly Warlock, only for Warlock to come back to then kill Thanos and then die for good himself. Not only did Marvel let Starlin do this, but they actually stayed away from "Starlin's" characters for the entire decade of the 1980s, out of respect to Starlin!
A decade later, Starlin returned to Marvel, and he quickly brought back all four characters, with Thanos showing up first in "Silver Surfer" (which Starlin had taken over writing duties on) and then the other three came back when Thanos put together all of the Infinity Gems to form the Infinity Gauntlet. Due to their residing in the Soul Gem after their deaths (a side effect of Warlock's powers when they died), Warlock, Pip and Gamora knew of THanos' plans, since the Soul Gem was part of the Gauntlet, and they all resurrected themselves to stop Thanos' plans.
In the end, Warlock ended up with the Infinity Gauntlet himself and saved the day...
However, he knew he couldn't keep the Gauntlet, so he split the Infinity Gems among a new group called the Infinity Watch, who would make sure that the gems wouldn't fall into the wrong hands again (Pip and Gamora were joined by Moondragon and another Starlin creation, Drax the Destrroyer)...
Warlock and the Infinity Watch were the centerpieces of the two sequels to "Infinity Gauntlet" that Starlin came up with, namely "Infinity War" and "Infinity Crusade." By the end of the 1990s, though, Warlock had seemingly died and instead ended up in the Ultraverse, an alternate reality filled with superheroes from Malibu Comics, who Marvel had bought in the mid-1990s.
For the most part, though, Warlock's adventures in the 21st Century have been whenever Starlin has returned to Marvel Comics to do miniseries and graphic novels, almost always starring Warlock and Thanos and involving the "Infinity" motif, like his miniseries last year with Alan Davis called "Infinity Entity."
With his impending movie debut, though, we're sure that Warlock will be more involved in the Marvel Universe very soon.