Warning: spoilers for Avengers: Endgame ahead.
As Avengers: Endgame brings a 22-film saga to a close, it pays tribute to the heroes who have been the linchpins of the series for over a decade now. Most notably, Endgame marks the end of the road for Robert Downey Jr.'s Iron Man/Tony Stark, who launched the whole Marvel Cinematic Universe in 2008 with the original Iron Man. Although Endgame breaks with tradition in that it doesn't have a post-credits scene, staying through the end credits does reveal one touching Easter egg — if you keep your ears perked.
As the (very lengthy) credits roll to an end, you can hear a strange clanging sound underneath the music. Sound familiar? It should. Disney confirmed to Vanity Fair that the clanging is, in fact, the sound of Tony Stark forging his first Iron Man suit. The sounds you hear are the same sounds that accompanied Tony creating his first proto-suit while in captivity in an Afghan cave.
Endgame is (presumably) the final appearance for Tony Stark, after he heroically sacrificed himself to save the universe in the final battle, as many had predicted. In a way, it's bringing the Marvel universe full circle: Tony was the character who launched the story, and this particular saga is over now. By paying tribute to him in the final moments of Endgame, it's as if the entire Marvel universe is paying tribute to its origins before moving forward into whatever is coming next.
And there's plenty slated for the future: Disney Plus is scheduled to launch several new TV series following characters such as Falcon, the Winter Soldier, Scarlet Witch, Loki, and more. Plus, there are other Marvel movies already in the pipeline, with Spider-Man: Far From Home launching the newest phase of the movie universe. Even without some of the original heroes, there are lots more Marvel superheroics to come!