Today, of course, we know the MCU as the Marvel Cinematic Universe, the steamrolling blockbuster-generating engine that has become the dominant commercial force in all of moviemaking. It was never a given that the Marvel Cinematic Universe would work. By the time the people at Marvel got around to establishing their own movie studio, they’d already sold off the rights to many of their most-famous characters: Spider-Man, the X-Men, the Fantastic Four. Only the relative dregs were left over, and nobody knew whether a relatively minor character like Iron Man could anchor a whole movie, let alone a franchise. It was a gamble.

It was a gamble, too, to cast Robert Downey Jr., a faded star who’d spent years battling his personal demons. It was a gamble to go against the sober, contemplative tone of superhero movies like Batman Begins or Superman Returns. Marvel instead found a light, quippy aesthetic—one that acknowledged the absurdity of the whole enterprise while still allowing for genuine adventure-serial thrills. (The Incredible Hulk, the second Marvel Cinematic Universe film, which came out a month before The Dark Knight, marked an altogether-unsuccessful reversion to that serious, heavy style.) The Iron Man gamble paid off spectacularly, many times over.

Iron Man wasn’t just a hit, and it wasn’t just a tremendously entertaining movie. It was the foundation upon which an entire movie institution was built. More than a decade later, Marvel is still running with that tone and that aesthetic, and it is utterly dominating everything else in Hollywood. Rewatching Iron Man today, it’s remarkable how much of what would later power the whole franchise is already there: S.H.I.E.L.D, Agent Coulson, Downey’s nonstop smirky patter, Tony Stark’s unfortunate tendency to power up his own enemies, the soothing robot voice that Paul Bettany adopted years before he found himself painted red and green. (It’s also a more intense movie than you might remember. I tried to show it to my kids, and they were done as soon as the missiles hit the convoy.) And with that famous Iron Man post-credits scene, Marvel set up a dizzying array of future-movie possibilities. And then it somehow made good on those possibilities. That’s amazing.

Iron Man’s importance, both to superhero movies and to cinema in general, cannot be overstated. And yet Iron Man was not the most important superhero movie of 2008. That distinction belongs to The Dark Knight, which was a genuine cultural phenomenon and which changed the way the public at large saw superheroes in the same way that Jaws changed sharks or Star Wars changed spaceships. Before The Dark Knight, superhero movies made money, but they were a sideshow. The Dark Knight made money, too; it was the highest-grossing movie of 2008. But it didn’t just make money. It was, in its moment, widely hailed as something resembling a masterpiece. When, for instance, the Academy Of Motion Picture Arts And Sciences failed to nominate The Dark Knight for a Best Picture Oscar, there was such a wide public outcry that the Academy changed its roles to allow for more nominees. That is an impact.

Now: The Dark Knight is a better movie than the perfectly okay Slumdog Millionaire, the movie that ended up winning Best Picture for that year. But it’s no masterpiece. The Dark Knight is jagged and propulsive, sometimes to a fault. Scenes rarely get a chance to linger, to establish dramatic presence. When, for instance, Bruce Wayne is getting ready to quit being Batman and let Harvey Dent take over as Gotham City’s protector, there is no emotional weight there; it’s just a storyline move. The movie includes the best action set piece in any Batman movie, the astonishing truck chase, but the regular fight scenes (like the ones in Batman Begins) are too choppy to be properly thrilling. There’s the long Hong Kong interlude, which is pretty and fun but also extraneous and dumb—a clear excuse to get some Batman ass-kicking into a stretch of the movie that was otherwise notably devoid of Batman ass-kicking.

And then there’s the last 40 minutes of the movie, where everything gets baggy and indistinct and sometimes dumb. The Joker gets an anticlimactic sendoff, dangling upside-down and trading barbs with Batman before Batman rushes off to find that Harvey Dent has become Two-Face. A surprisingly moving Tiny Lister moment saves a sequence that’s otherwise a dramatized version of a freshman philosophy-class thought experiment. And then there’s the whole thing about Batman bugging everyone’s cellphones, using a magical TV-bank doohickey to listen the Joker’s voice-waves (or whatever) while dumb-looking static-light things go over his eyes. For way too long, the movie turns into an episode of 24. When The Dark Knight came out, I can vividly remember seeing Glenn Beck on CNN, enthusiastically crowing about how the film was endorsing George W. Bush’s Patriot Act tactics. You never want Glenn Beck to think that you’re on his side.

For all that, though, The Dark Knight still represents a towering achievement, from the nasty economy of the opening robbery scene to the final goosebump moment where Gary Oldman intones the movie’s title. Christopher Nolan made a fantastically engrossing summer entertainment full of big gestures that still sustained a fevered, immersive mood. The whole idea of The Dark Knight is that insanity begets more insanity. Batman has gone to extreme lengths to keep his city safe, and then he’s forced to contend with the possibility that he’s only made things worse, inspiring a wave of bad guys that’s just as into symbolic gestures as he is. Throughout the movie, we see images of that insanity encroaching: piles of money burning, corpses dangling, a civic hero transformed into a hate-driven freak. It’s there in the filmmaking, too—in the drones and whines of the incredible score, in the way the disorienting cameras whirl around simple conversations. And of course, it’s there in Heath Ledger.

Ledger’s whole performance was a focus of widespread fascination before the movie had even come out. Before The Dark Knight, most of us figured that Jack Nicholson had already been the definitive Joker in Tim Burton’s 1989 Batman. (In an interview before The Dark Knight’s release, Nicholson said that he was “furious” that nobody had called him to be in this new Batman movie.) But then Ledger died of an accidental overdose months before the movie came out. This was one of the most truly shocking celebrity deaths of this century. It was River Phoenix all over again: a charismatic and talented young star who’d already proven himself as a talent and who didn’t really give off the image of someone who had problems like that.

Ledger’s death was sad, even for those of us who’d never met him. But I’ll speak only for myself here: In some dark and shitty corner of my mind, his death also made me more excited for the movie. Maybe, I thought, Ledger had pushed himself so far into darkness while making this movie that he didn’t fully know how to pull himself out. Maybe he had essentially killed himself in bringing this character to life. And maybe that deadly devotion would manifest itself onscreen.

Ledger’s death lent the movie a weird romanticism, sort of like the one that Kurt Cobain’s suicide gave to Nirvana’s MTV Unplugged In New York. Suddenly, we knew we were watching a major artist giving his last major work. This is the wrong way to think. There’s nothing romantic about death by addiction. It’s messy and shitty and sad, and it doesn’t fit into the pat narratives that we come up with.

And yet Ledger’s performance as the Joker really was magical—powerful enough that Nicholson’s Joker almost instantly became a faded footnote. As the Joker, Ledger is legitimately disgusting: dirty and scarred-up, with yellow teeth and a tongue that’s constantly darting in and out of his mouth, like a lizard’s. But he’s magnetic, too. He tells different stories about his scars, just so we’ll know that he’s always lying. He confounds criminals as badly as he does police. He dances his way through a hospital explosion and intimidates a roomful of mob bosses. His voice—the best description I can manage is a tweaked-out Richard Nixon impression—is chilling and alien. And he seems to be in love with Batman in ways that make even Batman uncomfortable: “Don’t talk like you’re one of them. You’re not.”

The criminal-mastermind stuff in The Dark Knight is fun. Even when you know it’s coming, the Joker’s escape from the police station is gripping; he’s putting such work into his schemes. And nobody’s ever handled a bazooka as nonchalantly as Ledger does during that chase scene. But the real great thing about The Dark Knight is the way the Joker has no real purpose—how his purpose is purposelessness. He calls himself “an agent of chaos,” which is both on-the-nose and accurate. We never get a real origin story for this Joker. He doesn’t even have a name. He’s just a force, a walking human entropy, “nothing in his pockets but knives and lint.”

He’s a hell of a storytelling device, too. Nolan’s real point with the movie, I think, is to illustrate how close so many of are to madness, how civilization is always hanging by a fragile thread. That’s why the movie’s central tragedy is in the way Harvey Dent falls apart, and that’s why Batman ends the movie by willingly transforming himself into a scapegoat. It’s a compelling arc, and yet Ledger’s Joker cuts such a powerful figure that it overwhelms the movie, turning both Dent and Batman into marginal figures. The most memorable image in the movie isn’t Dent’s Two-Face reveal or Batman disappearing back into shadow at the end. It’s the Joker, high on his own malevolence, hanging his head out of a cop-car window like he’s a dog.

Maybe Nolan intended for this to happen, and maybe he didn’t. Either way, he put together a cultural sensation that still has its hooks in us. Think of the way so many stray phrases from that beautifully written script have seeped into the lexicon: “You either die a hero, or you live long enough to see yourself become the villain,” “some men just want to watch the world burn,” “destined to do this forever.” The Dark Knight has entered the collective unconscious. It’ll always be with us.

And for that reason, I’d argue that The Dark Knight is the most important superhero movie in history, not just of 2008. The Dark Knight is the reason that the public at large is willing to take superhero movies so seriously. It’s the buzz that we’re still chasing. It’s the promise fulfilled. It’s a vast summer blockbuster made without even the slightest consideration given to entertaining children, which of course means that children love it. The Dark Knight is an influential movie, of course, with goobers like Zack Snyder and David Ayer attempting to use its all-pervading bad vibes in way more ham-fisted ways. But its importance goes far beyond that direct influence.

Iron Man was a miracle, of course, but I’d argue that after that, the Marvel Cinematic Universe didn’t produce another actual good movie for another three years. And I think The Dark Knight, just as much as Iron Man, is the reason that the Marvel Cinematic Universe is still around and still dominating. The Dark Knight showed Hollywood studios, and the public at large, what a superhero movie could be. After that, everyone had to try a whole lot harder.

Other notable 2008 superhero movies: We’ve already addressed Iron Man in some depth. There’s an argument to be made that Iron Man is the second-most important superhero movie ever made. Hell, there’s probably an argument that it’s the most important superhero movie.

But we should also talk about The Incredible Hulk, Marvel’s other inaugural MCU offering. Maybe it was brave of Marvel to attempt a reboot of their big green rage-monster only five years after the Ang Lee version. And the movie has some fun scenes, like a battle between the Hulk and some Army troops on a college campus. But French action-movie auteur Louis Leterrier gave the movie a drab, flat look, and star Edward Norton rewrote the script, making it heavier than it had to be. Marvel learned its lesson, adapting a bright and shiny in-house look and jettisoning both Norton and Iron Man’s Terrence Howard for actors who would play ball. In making these moves, Marvel effectively killed the primacy of both stars and directors, recognizing the characters and the storylines as the real draws. So now The Incredible Hulk is a historic scrapheap curiosity.

Another road-not-taken Marvel movie is Lexi Alexander’s almost hilariously violent Punisher: War Zone, the third and probably final attempt to turn Marvel’s brutal vigilante antihero into a movie’s leading man. In this one, Ray Stevenson plays Frank Castle as a gigantic stab-happy Jason Voorhees motherfucker, a stone-carved killing machine, while Alexander piles on the exaggerated slapstick gore and various character actors, led by Dominic West, do their best to make Castle’s victims into unsympathetic caricatures. Marvel is probably right that the Punisher is better in Netflix-miniseries form than as the star of a major motion picture, but I really love this movie’s hyper-violent absurdism.

With Hellboy II: The Golden Army, future Oscar winner Guillermo del Toro brought back the beloved cult-comics figure he’d already adapted and pitted him against a horde of magical Celtic-myth elf-creatures. Del Toro’s never been afraid of silliness, and Hellboy II has plenty of that. But it’s also a movie full of imaginative monster designs and gorgeous fantastical images. I don’t think it’s a classic, the way some people do, but it is top-shelf stoner spectacle.

Hancock is another curiosity: a big-budget summer movie about a newly invented superhero, a way-too-powerful unreliable drunk with mysterious origins and no idea how to function alongside the rest of society. The movie doesn’t altogether work, but it does make some fascinatingly strange turns, especially once we learn a few things about a couple of characters’ origins.

With The Spirit, meanwhile, comics legend Frank Miller, directing by himself for the first time, tried to make a CGI-heavy noir adaptation out of Will Eisner’s foundational superhero comic strip. The result is a notorious disaster, a self-important work of aestheticized nonsense that wastes the talents of way too many movie stars who should’ve known better. It’s the sort of movie that forces us to reconsider whether Frank Miller really was ever that great or whether he was just skating through his career on one hard-boiled cliché after another.

The Spirit villain Samuel L. Jackson, still in the process of becoming Nick Fury, was also a villain in Doug Liman’s Jumper, about a kid who discovers that he’s part of a secret teleporting race. The pretty-good animated movie Bolt gave us the story of a TV-actor dog who thinks he, like his TV character, has actual powers. Franklyn was a British movie with Ryan Phillippe as a masked crimefighter who travels between realities. The superhero-adjacent Wanted adapted a deeply toxic Mark Millar comic about a society of supernaturally gifted assassins. Meanwhile, the dumber-than-fuck parody Superhero Movie was a probably-premature joke-a-minute parody about the still-developing superhero-movie genre. But since the parody-movie genre was on its last legs at the time, and since the movie sucked, it didn’t make much impact.

Next time: Zack Snyder adapts Alan Moore and Dave Gibbons’ foundational comic-book masterpiece Watchmen into a confounding big-budget movie.