Stars of 'Marvel's Agents of S.H.I.E.L.D.' reflect on series finale

Tonight, after seven seasons, ABC's "Marvel's Agents of S.H.I.E.L.D." says goodbye with a two-hour finale starting at 9 p.m. ET.

The episode, "The End Is At Hand," has our heroes making a final stand against the nefarious Chronicoms, who want to erase S.H.I.E.L.D. from history.

Clark Gregg, who plays Agent Phil Coulson in the Marvel movies and on the show, told ABC News that over the years, the cast was convinced the show was kaput several times -- but now, it's for real.

"We've had a number of goodbyes, which has been kind of odd," he said. "[For] several seasons we ... didn't know if we were coming back, so we would say goodbye to everybody. Definitely at the end of season five, the last episode was called 'The End,' and it looked like we weren't coming back."

Gregg credits fans with saving the show because they "stuck with us and really became a kind of vocal crowd backing the show and pulling us off the bubble every year, so that by the end of it, we turned around and we'd done seven seasons and had this amazing journey."

Chloe Bennet, who plays Daisy Johnson/Quake/Skye, agreed.

"I really feel like I've grown up with [my character] ... on and off screen," she told ABC News. "I was so young when I started, and it's just been special to kind of take that journey along with so many other people -- like our fans."

Elizabeth Henstridge, who plays Jemma Simmons, reminisced about her on-screen romance with co-star Iain De Caestecker, who plays fellow scientist Leo Fitz. The pair were dubbed FitzSimmons by fans early on, but De Caestecker had his own ideas.

"What's weird to season one, me and Elizabeth, I mean, we protested as desperately as hard as we could that these two are brother and sister. There was no romance between them. And if there ever was, it would ruin the whole foundation of it, you know," he said.

Henstridge laughed, adding, "You protested more than I did, FYI ... I won."

De Caestecker laughed, but allowed of the onscreen coupling, "Sure enough, they wrote it in such a way that was like it's you know, it's impossible not to become invested in it."

For her part, Ming-Na Wen, who played steely Agent Melinda May, said of her last day on set: "It was a mixed bag, for sure. It was a sense of accomplishment that, 'Wow, we did this!' and we were able to celebrate that, and you know, [it was] very melancholy in other ways."

Bennet explained how she feels going into the home stretch: "I don't think it's still going to hit. You know, we still have the finale airing. And I think after that, I might feel different."

The Walt Disney Co. is the parent company of Marvel Entertainment and ABC News.