As much success as Clark Gregg has enjoyed as a working actor in Hollywood for nearly the past 25 years, he said nothing compares to the whirlwind he's been a part of since the first "Iron Man" movie came out in 2008.

Since then, of course, Gregg's star has risen considerably thanks to his recurring role as S.H.I.E.L.D. Agent Phil Coulson in "Iron Man 2" and "Thor" -- and as of 12:01 a.m. Friday, the character is back and bigger than ever with the ultimate assembly of Marvel superheroes in "The Avengers."

"It's amazing. It feels like only 20 minutes ago I was doing plays in New York and trying to break in and get a supporting thing in movies," Gregg told me in an interview Thursday. "I got some gigs in a lot of great projects and had fun in some independent movies, but at a certain point, you don't think you're really going to end up doing a big, leading role in a movie. You certainly don't think that you're going to be doing a movie as big as 'The Avengers.'"

Gregg, 49, said perhaps the most satisfying part of being a part of the entire "Avengers" initiative though the first two "Iron Man" films and "Thor" was knowing how much care directors Jon Favreau, Kenneth Branagh and Joss Whedon took took with Coulson: a character who could have easily been relegated to the shadows given the superhero status of his colleagues.

"It's something I never could have predicted for myself, to see Agent Coulson go from this character who wasn't in the comics who evolved during the first 'Iron Man,' and expanded through 'Iron Man 2,' 'Thor' and 'The Avengers,'" Gregg said. "Because I loved comics so much as a kid, it's almost more than my little heart can handle. To have the role organically evolve in the series -- and to have them not want to reduce the guy, but give him more to do as it moves along, I feel really honored by it."

"The Avengers" finds S.H.I.E.L.D. Director Nick Fury (Samuel L. Jackson) trying to prevent a world catastrophe when the villainous Asgardian demigod Loki (Tom Hiddleston) arrives on Earth with the intention of seizing an all-powerful sentient cube known as the Tesseract and using it to rule over mankind.

Knowing his only viable option is to assemble Earth's mightiest superheroes to battle Loki, Fury calls for the help of Iron Man (Robert Downey Jr.), Captain America (Chris Evans), Thor (Chris Hemsworth), Bruce Banner/The Hulk (Mark Ruffalo), Black Widow (Scarlett Johansson) and Hawkeye (Jeremy Renner). The problem is, the superheroes' super egos clash, and Fury, Coulson and Agent Maria Hill (Cobie Smulders) find themselves caught in the middle of the chaos.

Gregg thinks perhaps the biggest reason Coulson has resonated with Marvel movie fans is because, in a way, he's their direct link to the superheroes. In fact, in "The Avengers," Coulson tells Captain America how much he's admired the First Avenger his whole life and -- like a giddy comic book aficionado -- lets the superhero know that he's read "Captain America" comic books and has even collected his vintage trading cards.

"When you go to Comic-Con and see people dressed up like you, and develop a huge following on Twitter, you come to realize in a way, Coulson is the human face of the audience," Gregg told me, humbly. "Joss really hooked on to what that means by making Coulson sort of a fanboy -- someone, who for all his toughness and secrets, grew up reading 'Captain America' comic books. Coulson believes the whole dream about heroism. It's such an honor to be there for the fans and be their connection to the characters."

While it's thrilled Gregg to know that the Marvel movie arc leading up to "The Avengers" has met the expectations of diehard fans, the bonus has been the way casual comic book movie fans -- if not movie fans in general -- have responded to the material.

"Going to Comic-Con now, you discover that the fans of these movies aren't just boys, but boys and girls and men and women," Gregg enthused. "The cool thing about this is, Marvel has found people who didn't read comics, yet got them invested in these characters. Marvel created a perfect blend for all these movies. The films didn't take themselves too seriously, yet were about something when they needed to be."