Heath Ledger as the Joker in “The Dark Knight.” (Warner Bros/Everett Collection)

Ten years ago, “Iron Man” and “The Dark Knight” shook up the superhero-movie landscape, pushing aside such duds as “Ghost Rider,” “Catwoman” and “Elektra” and setting the stage for superhero movies to dominate Hollywood for years to come.

“Iron Man” would have the greatest impact, kicking off the many Marvel Studios movies leading up to this year’s “Avengers: Infinity War.” “The Dark Knight,” on the other hand, represented the best of what a superhero movie could be: a brooding, thrilling drama that takes its ideas seriously. At the time, critics and pundits saw it as an allegory for the Bush presidency and a commentary on the war on terror. Heath Ledger’s Joker has since become a meme, as fans online pair his image with harmless “Dark Knight” quotes or photoshop Joker makeup on political figures like Barack Obama, Donald Trump and Alex Jones. Yet today, the Christopher Nolan film, and particularly the Joker, typifies something more relevant: a prescient example of modern online troll culture.

Throughout the film, which will mark its 10th anniversary Wednesday, the Joker lies and kills just to undermine the moral authority of Batman (Christian Bale) and the city he defends. The Joker is many things: a psychopath, a villain, an anarchist. He’s also an alpha troll — a provocateur who’s impervious to pain and indifferent to decency.

Trolling has been around for decades. Even in early online forums, some users would bait others with an insincere argument. But the troll didn’t become an online identity until the mid-2000s, or right before the release of “The Dark Knight.”

Trolls are anonymous, and they laugh at the expense of others. Those same two qualities are key to the Joker’s allure: He has no obvious backstory, and he sees the world as a sick joke. “U mad bro” — a favorite tease of early trolls — has the same rhetorical bite as the Joker’s “Why so serious?” Like the best movie villains, there is some truth to the Joker’s worldview — that one bad weekend is all we need for society to collapse — and modern trolls share that yearning to push spaces (online and in real life) toward destruction.

Recently, trolls tried to prevent three black teenage girls from winning a NASA science competition. A page on the fan site Wookiepedia devoted to Kelly Marie Tran, the first Asian American actress to have a leading role in a Star Wars movie, was defaced by trolls, which many speculate was the reason she left social media (though she has yet to confirm that).

These examples show how online trolls have moved from the Internet’s underbelly into the public sphere. As Batman’s longtime butler, Alfred (Michael Caine), warns in “The Dark Knight,” “Some men just want to watch the world burn.”

No troll has prominently come out and cited Nolan’s film as a specific influence. But it’s plausible that “The Dark Knight” would fall into the same trap that “Fight Club” and maybe even “The Wolf of Wall Street” fell into: It was so compelling — and the villain’s arguments so forceful — that susceptible audiences took the wrong message. And with Ledger’s death, his Oscar-winning performance and Joker persona took on a mythic quality.

The relative innocence of online trolling back in 2008 — more personal, less weaponized — can be seen in the fan backlash to early negative reviews of “The Dark Knight.” When New York magazine’s David Edelstein was harassed online for panning the film, blogger Eric Snider noted that Edelstein’s review brought out “Joker-like tendencies”: “When you’re getting mad about a review of a movie that you haven’t even seen yet — that’s off the charts.”

Now it’s routine for self-identified trolls to wage war over superhero films before they’ve even seen them — for example, by intentionally deflating audience scores when they star minorities.

The nasty intersection of criticism and fandom doesn’t have the life-or-death stakes of the Joker’s wave of chaos, yet it speaks to a shared worldview: By harassing and intimidating anyone who strives for progress, trolls hope to keep our culture familiar, easy and, above all, monolithic.

In “The Dark Knight,” one of the Joker’s final acts is to deprogram Harvey Dent (Aaron Eckhart), Gotham’s fallen hero, into “an agent of chaos.” Dent’s tragic arc is the film’s emotional core, but his story has none of the Joker’s sinister resonance. In the 10 years since “The Dark Knight,” trolls have looked for large canvasses for their “jokes,” with some even bigger than Gotham City. Now that online life and real life have blurred, they have found them without even leaving their computers.