Iron Man director Jon Favreau has confessed the famous Nick Fury post-credits cameo was 'a lark' aimed at fans. When Marvel announced a plan to release solo movies for some of their biggest characters and then team all up for The Avengers, many in the industry believed it could never work. It was too risky and expensive, and all it would take is for one of the movies to bomb to derail the entire plan.

Thankfully the original Iron Man proved to be an enormous success, and while the quality of some of the Phase 1 movies could be found lacking, the anticipation for The Avengers built with each movie. Iron Man laid some key easter eggs for the Marvel Cinematic Universe, such as Agent Coulson working for S.H.I.E.L.D and most notably, a post-credits appearance by Sam Jackson as Nick Fury.

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While the scene announced Marvel were committing to the idea of The Avengers, Jon Favreau has admitted to EW that the scene started out as simply an easter egg for hardcore fans - and one he didn't take very seriously:

That was a bit of a lark. I wanted to include Easter eggs that the fans would appreciate and we thought the idea of a post-credit scene it could be fun. It was something that wasn’t really in the script originally. But I thought the idea of Nick Fury being Sam Jackson would be really fun, because when Nick Fury was reimagined in The Ultimates (comic book) they recast him as Sam Jackson, and I thought that that would be a really good nod to the audience. And Kevin [Feige, Marvel Studios executive] was way into it, too. Kevin really lit up. We worked on that dialog together. We were very careful how we selected the words. ‘You’re part of a bigger world now, a bigger universe,’ and ‘the Avengers Initiative,’ laid breadcrumbs for what was to come.

Of course its hard to imagine now that such a crucial scene for the MCU was essentially just an easter egg for fans. While many in the industry thought the idea of a shared cinematic universe would never work, once they saw the success of the MCU other studios started to replicate the formula. The DCEU has struggled somewhat with critics - aside from Wonder Woman - and while Justice League was a financial letdown, DC still has a slate of movies incoming. Other would-be shared universes like Sony's Amazing Spider-Man franchise didn't take off, while Universal's Dark Universe crashed and burned straight out of the gate with last year's The Mummy.

The entire MCU essentially grew out of that Iron Man post-credits scene, and after 18 movies of build-up, nearly every hero in the franchise is uniting for Avengers: Infinity War and its untitled sequel. Kevin Feige has said these two movies will be a 'finale' for the current version of the universe, and Phase 4 will introduce a new generation of heroes. It also seems likely some of the original characters will die, with many fan theories predicting Captain America and Loki as likely fatalities.

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Source: EW