SAN DIEGO – In a convention as dominated by strapping action stars and caped crusaders as Comic-Con International, a slightly-square guy who dons a business suit instead of spandex shouldn't be getting standing ovations. And yet Clark Gregg, who plays Agent Phil Coulson in last year's Marvel blockbuster film The Avengers and the upcoming Agents of S.H.I.E.L.D. television series, took the stage to some of loudest applause heard at San Diego Comic-Con this weekend.

"I'm a long-time Marvel fan, so every time I just can't believe this is happening to me," Gregg said during Friday's panel for the upcoming ABC show. He paused to gain his composure after the furor from the massive crowd, and then continued, "There's only one thing I really want to say, which is–"

"You're my favorite Avenger!" shouted a fan, interrupting the panel to much applause.

"You're my favorite person at the con!" he answered back. "Except Joss."

Joss Whedon, the writer/director of The Avengers, helped transform Agent Coulson from the slightly neurotic field operative of Iron Man and Thor into the superhero-card-collecting heart and soul of the Marvel Cinematic Universe. But while Whedon's everyman–or everyfan–take on the character may have opened the door for adulation, it was Gregg's portrayal that made him truly resonate. After all, Gregg is slightly square and he does love superheroes. He's the kind of guy that gets excited about online campaigns to bring his character back from the dead. He is, ostensibly, One of Us.

"To have Coulson get added to these other movies, given more and more meaty, amazing stuff to do and then–most movingly to me–to have it connect with the fans in a way where they ... waged a campaign on Coulson's behalf [after his death] is really moving to me," Gregg said after the *S.H.I.E.L.D *panel at Comic-Con. "Because he's them. He's an avatar for the fans, and a human in the world of super-humans."

Image: ABC

He's also something of an analog to Gregg himself. For years the actor has been the best supporting cast member on everything from The West Wing to The New Adventures of Old Christine. Now Coulson—the great Marvel Universe supporting character that never got enough screen time—is getting all the screen time.

And nobody's more surprised about it than Gregg. Back when director Jon Favreau, Gregg's then-neighbor, began to cast the first Iron Man film, he reached out to see if the actor wanted to come on board.

"I knew [he] was putting together an amazing cast for Iron Man and that was one of my favorite comics, and I got a call: 'It's a little tiny part, do you want to be in it?'" Gregg said. "And I was like, 'Yes! It's probably going to get cut out, but yeah!'"

Of course, it didn't get cut, and thanks to the shared cinematic universe that links the Marvel films, it lead to a recurring role as a S.H.I.E.L.D. operative in subsequent Iron Men flicks, Thor and, ultimately The Avengers.

"It’s a chain-letter that I'm always happiest to read because then I get to act it," said Gregg. Despite his humble bit part origin story, Coulson kept coming back in every successive Marvel blockbuster–at least, until he died in *The Avengers *at the hands of the supervillain Loki.

Then even Gregg thought he was done for good. But after The Avengers earned more than $200 million in its opening weekend–and more than $600 million in the U.S. alone–Marvel decided to expand its universe to the small screen at ABC, and Gregg's name came up again. Both Whedon and Jeph Loeb, Marvel's head of television, agreed that the superhuman-focused espionage agency of S.H.I.E.L.D. would be a great setting for a television show. The next words out of Loeb's mouth? "We'd really like to do it with Clark."

There was only one problem: Coulson had just been declared dead by no less than Nick Fury (Samuel L. Jackson) in the biggest movie of 2012. Still, death has always been a bit more flexible in the world of superheroes, where heroes like Captain America and Thor have been laid to rest (and resurrected) more than once over the years in the comic books. And so Gregg's character borrowed a page from perhaps the most superheroic trope of all, and managed to find his way back from the dead.

In the pilot episode of Agents of S.H.I.E.L.D., which airs in September but screened early at Comic-Con, the explanation for his resurrection remain unclear; Coulson offers one explanation of how he survived, but later in the episode Agent Maria Hill (Cobie Smulders) ominously insists that "he can never know" the truth.

However he managed to do it, Agent Coulson is back, and Gregg is getting standing ovations at Comic-Con simply for showing up. He still seems taken aback; before Iron Man hit theaters, after all, he was still just another guy in the massive crowds at Comic-Con, freely roaming the floor in search of his favorite Jim Starlin comics.

"Then the next time I came here–people were dressed up like me, you know?" Gregg said. In the aftermath of his big screen death, some of them even dressed up as gruesome zombie versions of Agent Coulson, something Gregg says he's not sorry he missed when he skipped the convention last year. "That would've been too upsetting for me," he joked.

Still, there was a little bit of prescience in those costumes. While he may not be shambling through the Marvel Universe, Agent Coulson has indeed risen from the dead, a boon typically bestowed on iconic heroes–and perhaps the biggest sign that he's well on his way to becoming one.