Hulks of a feather. Photo: Ladronn, Marvel Entertainment, and Marvel Studios.

It began with a simple pitch. Just a few words long, in fact. It was 2005, and comics writer Greg Pak was called into a meeting with Marvel Comics editor-in-chief Joe Quesada and senior editor Axel Alonso. He’d just been asked to write the monthly series Incredible Hulk, and the pair of higher-ups had an idea for his first story line. As Pak recalls, “It was kind of amazing, because basically all they said was, ‘Hulk comes to an alien planet and becomes a gladiator.’ And I think that was it.”

As the bard once put it, from small things, big things one day come. Pak, editor Mark Paniccia, and artists including Carlo Pagulayan, Aaron Lopresti, and Ladrönn built a tale from that micro-pitch that would go on to become the defining Hulk story of the past two decades, and easily one of the greatest ever told about the famed character. Entitled “Planet Hulk” and published from 2006 to 2007, it’s had the kind of iconic afterlife that few comics stories ever have. It’s given birth to stories in not one but three televised cartoons, shout-outs in two video games, an entire direct-to-video animated film, and sequels and spinoffs in comics form. But what sets it apart from nearly every other Hulk tale is that it’s made it to the most cherished spot in all of superhero fiction: a Marvel movie.

Despite not having the name Hulk in the title, this weekend’s Thor: Ragnarok is built on the solid foundation of “Planet Hulk.” A bevy of elements that Pak and his colleagues dreamed up are there: the debased planet Sakaar, the gladiatorial combat that takes place there, the Hulk-spurred Sakaaran revolution that takes down a capricious dictator, electrocution discs that keep slaves in line, the imposing helmet and armor the emerald Avenger wears in the arena, the genial rock-creature Korg and his bug buddy Miek, and — perhaps most important — the unusual Hulk-story trait of the green-skinned smasher actually finding some kind of home and peace a galaxy away from Earth. Given how ad hoc the pitch was and how untested the writer was, it’s remarkable — and admirable — that “Planet Hulk” made it this far.

At the time of the story’s debut, the Hulk was in a bit of a slump. He’d been kicking around since 1962, and had a dynamite concept behind him: mild-mannered scientist Bruce Banner is caught in an accident that makes him turn into a towering monster whenever he gets angry, and he subsequently has to escape both his inner demons and the forces that seek to destroy him. He’d had his fair share of beloved sagas — many of them written by longtime Hulk scribe Peter David — but it was hard to drum up enthusiasm for him in the mid-aughts. Part of the problem, as Paniccia sees it, was that Incredible Hulk was sorely lacking in, well, the incredible Hulk: “He’d kind of been off the table and it was more of a Banner-on-the-run book,” he recalls. A shake-up was in order.

The person who delivered it was an unlikely pick. Just a couple of years prior to Pak’s fateful meeting with his bosses, comics were alien territory for him as a creator. He’d made his bones as an independent filmmaker, directing the acclaimed and idiosyncratic sci-fi anthology feature Robot Stories in 2003. However, he’d long been a comic-book nut, and held special affection for the Hulk. Like many geeks of his generation (he was born in 1968), Pak was enchanted by the premier filmed superhero saga of the late 1970s and early ’80s: the Bill Bixby and Lou Ferrigno–starring CBS television series The Incredible Hulk. “That was the one show that I would change my schedule to watch,” Pak recalls. He then laughs and gets a little sheepish: “I joke about it, but it’s true: it was my introduction to the literary concept of tragedy. It was like, ‘Oh my God, it’s so sad!’”

So it’s no surprise that, upon snagging a gig writing mid- to low-tier comics for Marvel in 2004, Pak tried to level up and pen the adventures of his favorite brute. He started working for Paniccia on Marvel Nemesis, a series that tied into a video game, and exploited the fact that Paniccia was also editing Incredible Hulk at the time. “I’d been dropping these hints about how much I like the Hulk,” Pak says in an interview conducted along with Paniccia, who acquiesced and offered Pak the job.

“I’ll never forget asking you if you’d like to write the Hulk,” Paniccia says. “You just had this smile, like coast-to-coast smile on your face. I mean, you were like, ‘You know that’s my favorite character?’ I’m like” — here, he laughs — “‘Yes, I do. You’ve told me maybe one time.’” The alien gladiator pitch came soon after, and the pair was off to the races.

“We wanted to do something where we could let Hulk cut loose,” Paniccia says. “Because one of the problems with the Hulk is he’s so powerful, right?” It’s true: A core challenge of Hulk storytelling is dealing with the fact that he’s nigh invulnerable and incredibly strong, thus making it hard to plausibly threaten him and even harder to show him in typically angry action without causing unheroic death and destruction. An alien environment would provide the twin conceits of sci-fi mishegoss that made him weaker (he’s transported through a wormhole that diminishes his powers) and inhuman enemies who could withstand his rage. What’s more, it allowed for unusual new costuming: Hulk in a mohawked helmet and leather skirt, with a metallic covering on one of his arms.

In fevered weekly meetings with Paniccia in New York City, Pak would spout ideas he’d conceived after reading through a biography of Genghis Khan, tomes about Roman gladiators, accounts of Spartacus’s slave revolt, and Sun Tzu’s The Art of War. But pop culture was just as important as high culture for him: The locational moniker Sakaar was born as an homage to the consonant-filled planet names of comics creator Bill Mantlo’s 1980s series The Micronauts, especially the craggy world known as Spartak. “It was like, you put a K in the name and it sounds pretty awesome,” Pak says with a chuckle. Hulk couldn’t be alone in this new world, so that meant the addition of a new supporting cast. Pak dug into ancient Marvel history and invented fellow gladiator Korg as a member of a race of rock-carapaced aliens called the Kronans, which had debuted in 1962. However, the buglike gladiator Miek was all Pak, devised as an underdog who would eventually get power-drunk once he was liberated, leading to a betrayal of his big, green buddy.

Excerpt from “Planet Hulk.” Photo: Marvel Entertainment and Carlo Pagulayan.

More and more extraterrestrial figures flowed out of Pak’s head and, brought to life by Pagulayan and Lopresti’s pencils, readers got to meet them after Incredible Hulk No. 92 launched the story line in February of 2006. The story cycle retains its power a decade later. Its basic outline is simple but operatic: some of the top Marvel superheroes get sick of having to clean up the Hulk’s mess and launch him into space, he gets sucked into a wormhole and arrives on Sakaar, he’s enslaved as a gladiator, he and other gladiators lead a rebellion and overthrow the planet’s king, Hulk becomes the new king and falls in love, an accident with the ship that brought him to Sakaar causes the deaths of his love (though that was later revealed to be a bit more complicated than it seemed) and scores of his people, then Hulk and a group of his new pals come to Earth to exact revenge on the heroes who exiled him, leading to the next story line, “World War Hulk.”

The whole thing felt fresh in a way Hulk stories hadn’t in a long time. For one thing, there was the new setting and set of characters; so, too, it was exciting to see the Hulk take over and rage out, as opposed to being stuck with puny Banner as the main character. But the real magic of the story lies in the fact that Hulk gets to find a place for himself in a way he never did on our world. Once he’s in charge and falls for his romantic partner, the warrior Caiera, he seems somewhat comfortable.

“I loved the idea of Hulk being a hero on a planet and being a bit more introspective and being a bit more quiet,” Thor: Ragnarok director Taika Waititi tells Vulture when asked what he loves about “Planet Hulk.” “Because every Hulk version we have seen in the past is just him turning into Hulk and smashing everything, but to see a Hulk now quiet and sitting there like General Kurtz from Apocalypse Now in a hot tub? It is a way more interesting character.”

Ragnarok co-screenwriter Eric Pearson was similarly taken by that element. “He’s filled with rage, but if you give him a place where he can get that rage out and, of all things, be cheered for it — the opposite of Earth, where it’s his curse — then it’s kind of the recipe for Hulk to live a Banner-free life and be able to settle down, almost,” he says. “It was important for me in the script to have that moment where you see that Hulk is calm but he’s not turning back into Banner.”

Readers were enchanted at the time, too. Despite being launched with little fanfare, “Planet Hulk” generated great reviews and word of mouth. “The Hulk is finally good again,” declared reviewer Hilary Goldstein of IGN. Comics Bulletin’s Dominic Davies wrote that it was “a fantastic tale of violence, liberation and pure Hulkdom.” Typically, sales of a comics story decline as it goes on and the initial blush wears off, but according to industry-analysis site Comichron, retailer orders for Incredible Hulk actually rose by roughly 35 percent from the first issue to the last, with multiple printings for sold-out installments along the way. It’s now regarded as canonical, regularly topping lists of the best Hulk stories ever told. (According to Paniccia, when Hamilton star Okieriete Onaodowan visited the Marvel offices recently, he went out of his way to say that it’s one of his favorite Marvel epics.)

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It’s no wonder, then, that “Planet Hulk” popped into Marvel Studios chief Kevin Feige’s head nearly a decade later. At the end of the script for 2015’s Joss Whedon–helmed Avengers: Age of Ultron, Hulk hops into a flying contraption called a Quinjet and scoots away to be left alone. When that was written, Feige had no plans for a “Planet Hulk” adaptation — perhaps because the movie-rights situation for a solo Hulk flick remains complicated — but his thinking evolved. Thor actor Chris Hemsworth wanted to have other Marvel characters to play with in the planned Thor threequel. “[W]e were like, ‘We need something big,’” Feige told the Wrap. And who’s bigger than the Hulk? He spoke with a brain trust and realized what they needed to do. “We would jokily call it ‘Planet Thor,’ for a while. I went, ‘You know what that means?’ They go, ‘What?’ I go, ‘That means Hulk went to space at the end of Ultron.’” Et voilà: A partial “Planet Hulk” adaptation was born.

The finished film adds and changes a great deal, of course. After all, it’s a movie about Thor, so our introduction to Sakaar comes when that titular god of thunder ends up enlisted in gladiatorial combat there. Gone is Pak and Pagulayan’s original king of the planet, replaced by Jeff Goldblum’s eccentric Grandmaster. Although Korg and Miek show up, they’re a small part of the story, and Caiera and the rest of Hulk’s revolutionaries are nowhere to be found. And, of course, there’s a lot of stuff about Thor’s native Asgard and its various supporting characters, all of which comes from entirely separate comics sources.

None of that bothers Pak or Paniccia, who attended a screening earlier this week and adored what they saw. Indeed, talking to them, one is reminded of how odd it is that comic books, a dirt-cheap medium that only requires the creative efforts of a small number of people on any given story, are now the source material for enormously complex and massively expensive mass-market products. “The first time someone says ‘Sakaar,’ it just cracked me up,” Pak says with a little laugh. “That’s a name that I made up, like, pacing around my living room, trying to think of a cool name for a planet. To see it in a big movie like that? It’s a trip.”