Stars David Duchovny and Gillian Anderson and writers revisit their groundbreaking series

During its heyday, The X-Files could be a truly frightening show. Airing from 1993 to 2002, the groundbreaking sci-fi series found FBI agents Fox Mulder and Dana Scully investigating all manner of ghouls, monsters and aliens, all the while digging into a vast government conspiracy that would give any little kid nightmares.

But for all of the show's intense subject matter, X-Files stars David Duchovny (playing the true believer Mulder) and Gillian Anderson (the more science-minded Scully) also had plenty of funny moments. And their famous comedic chemistry was on full display at San Diego's Comic-Con International yesterday, as they cracked jokes and reminisced with X-Files producers and writers in a panel celebrating the series' 20th anniversary.

Right off the bat, the moderator – Michael Schneider of TV Guide – threw a hardball, asking Duchovny and Anderson if they have a different perspective on anything from the show after all these years. Seemingly flustered, the two actors paused for a moment before Anderson – looking nice with blond hair and in a black dress – said something saucy.

"I guess I didn't realize that Mulder was so cool until a few years later," she said. "And I thought, 'Damn, shoulda got there sooner.'" (They did eventually hook up towards the end of the series.)

Speaking to a packed house in a cavernous ballroom at the San Diego Convention Center, Duchovny and Anderson were joined onstage by X-Files writers and producers Darin Morgan, Glen Morgan, John Shiban, Howard Gordon, Jim Wong, James Amann and Vince Gilligan, who has since become the mastermind behind the hit AMC series Breaking Bad. Gilligan said he learned the TV ropes while writing X-Files episodes.

"There'd be no Breaking Bad without The X-Files," Gilligan said. "It was like going to film school, except getting paid to attend, and I was lucky as hell I was a part of it."

X-Files creator Chris Carter was also onstage, and he said he crafted Scully's character based on the idea of his "fantasy woman": "Strong and smart and opinionated and resourceful. Tough. All those things that I like."

Later, during a Q&A session, one woman told Anderson that she was inspired to pursue a doctorate in physics because Scully's character had majored in the subject.

Duchovny seemed open to pairing up with Anderson for another round of paranormal investigations at some point in the future. "The show is so flexible, and could encompass so many different ideas, that I think we could do it forever. I always thought, whenever we can do it – come back together – we would.

"So, we will, as much as we can," he added.

But Carter, when pressed repeatedly by Schneider, never said he'd actually want to work on a third X-Files movie. Though he didn't say he wouldn't, either.

"I have to say, just being here today and seeing all these people . . . You need a reason to get excited about going on and doing it again, because it's hard, hard work," he said, before getting cut off with loud applause and cries of "Do it again!"

The X-Files panel was one of the highlights of the day. Some fans had arrived to the Convention Center as early as 6 a.m. to ensure they could get into the ballroom. But when it all wrapped up, many cleared out to make way for another batch of fans, these eager to see a handful of iconic young TV stars – Matt Smith of Doctor Who, Steven Yeun of The Walking Dead, Tyler Posey of Teen Wolf, David Giuntoli of Grimm and Kit Harington from Game of Thrones – sitting in on Entertainment Weekly's "Brave New Warriors" panel.

Harington, who plays the tough, canny, kind-hearted bastard Jon Snow on Game of Thrones, opened up about the heart-wrenching scene in the final episode of Season Three in which he breaks up with his wildling girlfriend, Ygritte, only to have her shoot him with a bow and arrow.

"I don't know if it was brave or cruel, but when he had to leave . . . her," Harington said about Snow, when a fan asked what his most defining moment of the series was thus far. "He was doing it for her, essentially," he added, as the audience erupted with a mix of angry cries and sympathetic awwws.

Harington also revealed that he and Snow share a similar, sensitive outlook. "I can be quite emo," he said. "If Jon had an iPod, it would have exactly same type of music I would listen to."

Rounding out the night in another packed ballroom, producers and cast members of Dexter bade farewell to thousands of fans in a panel commemorating the show's eighth and final season. Michael C. Hall, executive producer and star, described how it might be hard letting go of his character, Dexter Morgan, the police blood-spatter specialist who's been moonlighting as a serial killer since 2006.

"Our conscious minds are aware that it's over. And as much as it is for some of us, there are people involved in the post-production process who still have work to do," he said. "Probably our bodies, five months from now, will start knocking at the door, wondering why we're not doing Dexter again. I think there's probably some unconscious part of us that hasn't accepted it yet, or even recognized it yet."

Asked by a fan how he handles stress, he said he isn't quite sure now that the show's coming to an end.

"Honestly, pretending to be Dexter has been a stress-reliever in its way, so I don't know what I'm going to do now," he said. "Exercising is good. You know, anything that gets your heart beating."