"Marvel's Agents of S.H.I.E.L.D." will reference the rest of the Marvel Universe, but the characters will ultimately stand on their own, executive producer Joss Whedon said Sunday.

Asked if Disney-ABC saw the upcoming series as an opportunity to promote other Marvel characters, Whedon said at a Television Critics Association panel that he sees that as "a fun opportuntity — it's not the reason behind the show."

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"We don't just want to be an Easter egg farm," he said. "We want people to come back because of these people and not because of some connection to the movie universe. This show has to work for people who aren't going to see those movies and haven't seen those movies."

If any such people exist. The movies of which he spoke include the "Iron Man," "Thor," "Captain America" and "Hulk" films — as well as Whedon's 2012 blockbuster "The Avengers." All of the characters are referenced in the show's pilot episode, as is The Black Widow. And "Spider-Man" fans will recognize a reference to him as well.

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Another familar name: Agent Phil Coulson, who debuted in "Iron Man" and seemed to die in "The Avengers." It's no spoiler to say he's back in the series, though the pilot episode doesn't explain exactly why he's alive. The explanation "will be drawn out over several episodes," Whedon said.

"S.H.I.E.L.D." is the biggest swing this season for ABC, the fourth-place network in the key 18-49 demo. The show's producers and stars were asked if they felt responsible for the fate of the network.

Executive producer Jed Whedon said the writers just try to keep it light and fun.

"One of the things we try to do is keep it the way it always is," he said. "If we think about it all the time we will never make any decisions."

Added Clark Gregg, who plays Coulson: "How long's ABC been around? Like 75 years, right? I feel like they're going to outlive us no matter what we do."

The show is a family affair: Jed, Joss' brother, will showrun with his wife, Maurissa Tancharoen. Jeffrey Bell is the third showrunner.

Joss Whedon, who directed and co-wrote the pilot, said he will remain involved in the series "as much as an executive producer can who's also making a movie." (That movie is the sequel "The Avengers: Age of Ultron.")

The "S.H.I.E.L.D." pilot looks expensive enough, Gregg said, that he worried the second episode would feature the agents of S.H.I.E.L.D. hanging out in an elevator. But instead, "the second one, if anything, is bigger and more exciting."

Gregg also announced Sunday that he would be tweeting the first phase of a new "S.H.I.E.L.D." promotional poster from his account, @clarkgregg. Once it receives 3,000 retweets — probably by the time this story posts — his co-star, Ming-Na Wen, will tweet more of the poster from @MingNa.