One of the Marvel Cinematic Universe's most enduring staples has been its use of post- and mid-credits scenes, also known as a "tags" or "stingers." This signature addition has been present since the MCU's inception, starting with with 2008's Iron Man. As the theatrical debut of Avengers: Infinity War approaches, Marvel Studios President Kevin Feige revealed how the very first post-credits scene came to be.

"It occurred to us [while making Iron Man], ‘Well, we don’t have X-Men, we don’t have Fantastic Four, we don’t have Spider-Man, but we have everything else,'" Feige explained to Entertainment Weekly. "Even though everything else hadn’t been turned into a big film before, or had the name recognition among non-comic-book readers that others ones did, we had the opportunity to start putting certain heroes in other heroes’ movies, which hadn’t been done before. It’s a bonus of what’s to come."

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For Feige, the idea of the audience being rewarded with a special scene after sitting through the credits came from an unlikely source: the 1986 comedy Ferris Bueller's Day Off. "It was the greatest thing in the world," Feige recalled. "I thought it was hilarious. It was like a little reward for me for sitting through the credits."

"We wanted Nick Fury to be the character to intertwine characters, but we didn’t want to interrupt the movie. You know, if Sam Jackson in an eyepatch showed up in the middle, it might be jarring," he continued. "What do we think would be a fun thing slightly outside the narrative, but tied to the grander overall narrative, that would be the fun reward for people sitting through all of our names?"

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Including Infinity War, Marvel Studios has released 19 films to date. Each one has included a post-credits scene in some form or another, varying in importance; Guardians of the Galaxy Vol. 2 even had a whopping five post-credits scenes. Infinity War will continue the tradition.

Directed by Joe and Anthony Russo, Avengers: Infinity War stars Robert Downey Jr., Chris Evans, Chris Hemsworth, Mark Ruffalo, Jeremy Renner, Scarlett Johansson, Anthony Mackie, Paul Rudd, Elizabeth Olsen, Tom Holland, Benedict Cumberbatch, Chadwick Boseman, Chris Pratt, Zoe Saldana, Dave Bautista, Bradley Cooper, Vin Diesel, Tom Hiddleston, and Josh Brolin. The film arrives April 27.