Since then, several further films produced by the fledging Marvel Studios (as opposed to those Marvel properties controlled by other studios, like the Spider-Man and X-Men films) have continued to embrace this notion that all these heroes exist in the same "universe", and it all culminates in The Avengers, which opens next week. (N.B. As I write this, I have not yet seen The Avengers).
Robert Downey Jr. turned up in the same year's The Incredible Hulk; Samuel L. Jackson was back for 2010's Iron Man 2, and brought Scarlet Johansson's Black Widow with him; Clark Gregg's Agent Coulson had a cameo in last year's Thor along with Avenger Hawkeye (Jeremy Renner); and most recently, Tony Stark's dad Howard (played by Dominic Cooper) appeared in Captain America: The First Avenger, the end of which seems to lead directly into The Avengers.
The idea of various big films (that aren't merely sequels to each other) all inhabiting the same universe is a bold story-telling technique that I find particularly exciting. What's even more amusing is that it's exactly the same point of difference that took Marvel Comics to the top of the comic book industry starting in the Silver Age of the medium - the early 1960s.
Upon introducing such instantly iconic characters such as the Fantastic Four, The X-Men and Spider-Man (not to mention various Avengers, although Captain America had been around since the 1940s), Marvel head-writer Stan Lee promptly had them pop up for cameos in each other's comics.
Until this point, comic books had little in the way of a consistent continuity, especially amongst different titles released by the same publisher. But Lee decided have characters in one comic reference incidents in others.
It's par for the course these days, but back then it proved so successful with comic book fans it helped Marvel come to dominate the comics industry over it's main rival DC, which had more recognisable characters such as Batman and Superman.
It's fascinating to me that fifty years later, Marvel Studios are using the exact same technique to build up their filmic universe, and I can't wait to see how it comes together in The Avengers.
I've been wracking my brains trying to think of other instances of this kind of universe building in movies. It's definitely never happened on this scale before, but there are examples.
One of my favourites is how Michael Keaton popped up briefly in Steven Soderbergh's 1998 film Out of Sight as Ray Nicolette, the character he played in Quentin Tarantino's Jackie Brown, released the previous year. Both films were of course based on books by Elmore Leonard. I would pay good money to see a Ray Nicolette film.
Whit Stillman, who I've discussed at length in this blog before, is very fond of having characters from one of his film's cameo in another. The Last Days of Disco (1998) has Stillman stalwart Taylor Nichols appear as both his character from Metropolitan AND his character from Barcelona. Endless repeat viewings of his films have alerted me to how Stillman likes to have various characters across various films casually name check each other aswell.
Clerks and Mallrats director Kevin Smith has done quite a bit of this sort of thing aswell, even going so far as to name his universe - he called it the View Askew Universe aftger his production company. You only need to watch Smith's films to realise how comic book-obsessed he is, so it's not hard to imagine where he got the inspiration for this sort thing.
More recently Get Him To The Greek made humorous reference to some of the characters from the movie it was spun-off from: Forgetting Sarah Marshall.
Some of this sort of stuff only exists on an in-joke level - it's very appealing to imagine that John Travolta's Pulp Fiction character Vincent Vega is the brother of Vic Vega, the character played by Michael Madsen in Tarantino's previous film Reservoir Dogs, but the film never states it, so I don't really count it.
The kind of universe building I've discussed in this blog occurs much more often in books than in movies, but I really hope it manages to flourish in the filmed medium.
Can you think of other examples of movie universe building, or characters jumping between films? Do you get a thrill out of such things?