There they were in the midst of what looked like a spooky old-growth forest (Princess Park, actually, mere blocks from upscale suburban homes here), surrounded by clumps of moss, overgrown ferns and gigantic Douglas firs, looking for clues of yet another allegedly paranormal crime, the kind they used to solve almost every week. They addressed each other, as they always had, by only their last names.
“Mulder,” said Gillian Anderson, reprising her role as the F.B.I. agent Dana Scully, the look on her face instantly recognizable; part reprimand, part in-spite-of-herself affection.
“Scully,” David Duchovny responded in character, somehow managing to mock her just by saying her name.
They were shooting the much-anticipated six-episode revival of “The X-Files,” which begins Sunday, Jan. 24 on Fox, back in Vancouver, where the original series’s first five seasons were filmed. It’s been 14 years since an original episode aired, almost 23 years since the show began. In 1993, the two actors had no idea they were about to start a phenomenon that would propel them to worldwide recognition, demonstrate the power of genre television and mark them, whether they liked it or not, as Mulder and Scully for the rest of their working lives.
“For a very long time, I just could not think about it anymore; I was so ready to be done,” Ms. Anderson said, remembering the grind of doing about 25 episodes a year for nine seasons. Virtually unknown and only 24 years old when she landed the part, she worried for years that the role would swallow her entire career. When the series ended, she moved to England and made a point of taking parts in higher-brow productions such as the BBC adaptation of Charles Dickens’s “Bleak House.”
Only in recent years has the idea of returning to the Scully character seemed enjoyable. “If I was to look at the bell curve of my ego, I would say that it would have been harder at other times to do this series again, had I not proved to myself — and to other people — in the interim that I could do other things,” Ms. Anderson said.
When it first aired, “The X-Files” was not a sure thing. The initial audience (an average of 11 million viewers per episode in the first season) was small but intensely loyal, invested in not only the supernatural stories but also the dynamics of the Scully-Mulder relationship. By its fourth season in 1996-97, the series had exploded into a mainstream hit, 11th in Nielsen ratings and averaging 20 million viewers per episode. (It also spawned two films, “The X-Files” in 1998 and “The X-Files: I Want to Believe” in 2008, the last time they played Mulder and Scully.)
“Without ‘The X-Files,’ you don’t have shows like ‘Lost’ or ‘Heroes’ or even ‘Bones,’” Mr. Duchovny said. “There were all these tributaries that came out of the show, this whole Comic Con-ization of the world.”
He added: “I think it became more than any of us saw, certainly more than I saw. I was not interested in aliens, and that’s what I assumed the show was about. So I was completely wrong.”
Chris Carter, the creator of “The X-Files” and still its driving force, didn’t care much about aliens, either. But he was fascinated by how many other people seemed to be. In the early ’90s, supermarket tabloids like Weekly World News and airport paperbacks like Whitley Strieber’s “Communion” were filled with tales of U.F.O.s and alien abductions. The idea of a show about conspiracies, real and imagined, appealed to him. It took several tries before he could persuade Fox, where Mr. Carter had a development deal, to give the concept a shot.
The underlying premise, Mr. Carter believes, is even more relev