Think of Nick Fury as the spy who came in from the credits.

During the making of the first "Iron Man," Samuel L. Jackson was invited to film a quick scene in the role as "a tag," one of those short (and often funny or sequel-suggesting) snippets of film that roll after the credits.

The Fury tag was especially fun because in Marvel Comics, the modern incarnation of spy-chief Fury was in fact modeled after Jackson.

The tag also turned out to be one of heck of a job audition for Jackson — he's signed a nine-movie deal with Marvel Studios to make his fictional espionage czar the unifying crossover character as Marvel moves forward with a plan to interlock all its superhero films.

"The idea was just to do this tag, and we thought it would be really fun to get Sam since the comics version of Fury is based on him," said "Iron Man" and "Iron Man 2" director Jon Favreau. "Now it's become much more than that. In the ("Iron Man 2") film, he has a significant role and becomes the entry point to connect Tony Stark to the agency called S.H.I.E.L.D. and, thereby, the rest of the Marvel Universe, with Captain America, Thor, the Avengers."

In "Iron Man 2," Fury is a bit slippery — he shows flashes of candor and empathy in his dealings with billionaire superhero Stark, but he also makes some Machiavellian moves that make it clear that his pragmatism is greater than his patience when it comes to S.H.I.E.L.D.'s secret agenda.

In Jackson, Favreau says, Marvel has a charismatic player with a black-ops grin who can hold his own in a room full of superpowered types.

"He has tremendous presence," Favreau said. "We have a scene in the film at Randy's Donuts where Tony, after a rough night, needs a talking-to. And as Fury, Sam is a combination of sponsor and mentor and also this mysterious guy who is indoctrinating him into this order of superheroes."