'Agents of SHIELD' Star Clark Gregg Reveals Why He Returned After Coulson's Death

At the end of the fifth season of Marvel's Agents of S.H.I.E.L.D., the leader of the team finally succumbed to wounds suffered in The Avengers and Agent Phil Coulson died.

But actor Clark Gregg is returning for more episodes of the Marvel Television series, despite the fitting emotional end his character received. Gregg addressed his return to the series, explaining his decision in an interview with Entertainment Tonight.

"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," said Gregg. "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."

Gregg explained that the happy ending made him uncertain of his future with the series after the renewal and that he needed a reason to justify his return.

"I didn't know if it was going to involve me," Gregg added, "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.'"

The actor addressed his new role being a key reason for his return because Gregg is playing a character who is most definitely not Phil Coulson, as teased in the new trailer.

"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. 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."

Fans will learn the mystery behind why Gregg is back, and who his strange new character is, when Agents of S.H.I.E.L.D. returns to ABC later this summer.