'Agents of SHIELD': Clark Gregg on His 'Disturbing' New Character & What's to Come in Season 6 (Exclusive)

clark gregg agents of shield

The actor is playing a 'very different person' in 'S.H.I.E.L.D.'s upcoming season.

Phil Coulson is dead... so who's that guy in the new Agents of S.H.I.E.L.D. trailer?

The Marvel TV series returns for its sixth season this summer, an announcement that took even the cast and crew by surprise when ABC renewed the show for two more seasons last year.

"We had this really wonderful end of season five -- the [season finale] episode was even called 'The End' -- and we had reason to believe that we were done," series star Clark Gregg told ET's Philiana Ng at the Television Critics Association press tour on Tuesday. "We’d had these wonderful five seasons and a very tight family, and it was very, very sad. And then they called everyone up and said, we’re actually gonna do two more short, 13-episode seasons, which is really the number we thought we always could do best at."

The decision presented a bit of a snafu to the S.H.I.E.L.D. creative team, due to the fact that Gregg's character, Agent Phil Coulson, died at the end of season five -- after an encounter with the Spirit of Vengeance wiped out the Kree compounds in his system, which had brought him back to life after he was killed in the first Avengers movie.

"I didn’t know if it was going to involve me," Gregg explained of S.H.I.E.L.D.'s subsequent seasons, "and if it was going to involve me, I thought it had to be something special, something very different. I didn’t want to just kind of like, go, 'Oh, never mind, it turns out he was OK all along.'”

That doesn't seem to be the case with Gregg's mysterious new character, who makes an appearance at the end of the series' newly released teaser trailer, claiming that he's "never heard of" S.H.I.E.L.D., the organization to which Coulson devoted his life and legacy.

"What [producers] Jed and Mo Whedon and Jeff Bell came up with, with the other writers, fulfilled all those criteria," Gregg explained of his return. "And I’m really excited for people to see what they came up with. It may be a little disturbing, but this is a very different person."

"There’s a big mystery here," he added. "And I think that this person is as surprised as they are, that they seem to recognize his face... I probably wasn’t supposed to say that."

While the actor doesn't have too much info on what's to come in S.H.I.E.L.D.'s future seventh season, he did offer a few hints at season six, which, as the trailer shows, kicks off with Mack (Henry Simmons) taking over director duties in Coulson's absence.

"I know that season six starts out with the S.H.I.E.L.D. team on Earth, grieving, trying to take on on the duties of S.H.I.E.L.D. and dealing with these strange anomalies that have wreaked mass chaos, and they seem to get some images of people from somewhere else who are committing these things," Gregg explained. "The other half of the team is off in space, looking for the frozen Fitz from the future... And suddenly, it becomes clear that one of these people is wearing a very familiar face."

"I don’t know what people are going to think, I do not know," he marveled of the series' new creative direction. "That’s what I like about the show. They have a great bravery in terms of throwing out all the rules and taking risks. And they’ve really taken one this year."

Marvel's Agents of S.H.I.E.L.D. returns this summer on ABC.