"Avengers: Endgame" is one of the most eagerly anticipated movies of 2019. It already has shattered Fandango’s pre-sale tickets record. (Chris Pizzello/Invision/AP)

Marvel fans beware.

With less than two weeks before “Avengers: Endgame” hits theaters nationwide, spoiler-filled footage has leaked online, spreading on Reddit and Twitter.

Social media users posting video clips and still images from the movie, which has shattered Fandango’s pre-sale tickets record, have already seen their content disabled on copyright claims. But the damage is done, at least for some of the clip’s viewers.

Marvel did not immediately respond to a request for comment.

The spread of such leaks can be devastating for filmmakers and fans alike. Footage of “Endgame,” the final chapter of an interwoven story that Marvel Studios has been building since 2008, across 22 movies, has been closely guarded. And the hotly anticipated movie is expected to break box office records, while it concludes an ambitious cinematic project that relied on jubilant fan engagement.

As The Washington Post’s David Betancourt has noted, “Endgame” trailers have given viewers little to chew on. The film is expected to answer questions raised by “Avengers: Infinity War” about the fates of the galaxy’s mightiest superheroes. The trailers span just 10 combined minutes for a movie that clocks in at three hours and two minutes.

The total volume of the leaked footage is unclear, and it’s likely that inadvertent exposure to the spoilers won’t deter Marvel’s biggest devotees. But fans are urging caution.

Twitter declined to comment. But the spread of the leaked “Endgame” clip comes as the platform faces criticism of overreacting to copyright claims. After the file-sharing news website TorrentFreak recently published a story about leaked episodes of several TV shows, Twitter removed several tweets that linked to the article. As Gizmodo reported, the company also deleted subsequent tweets about the Twitter deletions.

The panic over the “Endgame” spoilers and the excitement tied to the movie’s release reflect the significance of the story’s end, which has marshaled intense fandom and has reshaped the superhero movie genre, while altering the movie landscape. Collectively, the films of the Marvel Cinematic Universe have earned more than $18 billion. Of the top 10 highest-grossing movies of all time, four belong to Marvel.

The film, as its title makes clear, is also a culmination of the Avengers story line, with several major characters expected to make their final appearances. But Marvel’s interconnected storytelling, where movies build on previous releases and characters crisscross plotlines, will continue. Marvel is developing several new film projects. Later this year, Disney will launch its new streaming service, Disney+, which will feature fresh Marvel shows that will connect with the movies.

One Disney+ show is a “What If” series that will take fans down alternate story paths, such as what if Peggy Carter took the serum instead of Steve Rogers, remaking Captain America.

Disney declined to comment for this report.