Once in a while, David Duchovny - Fox Mulder in the hugely successful TV series The X-Files - feels the need to break out of the celebrity straitjacket. An appearance on American shock jock Howard Stern's live radio show, for instance, is normally enough to make the 37-year-old actor feel liberated from the saccharine treatment meted out to A-list personalities.
While others who share his level of fame would run a mile at the very sight of Stern, who has built a career out of humiliating the rich and famous, there is something in Duchovny that positively courts his favours. Indeed, he was mortified once when, having tried to arrange an appearance, he was turned down by Stern, who dismissed him as a "fake Richard Gere".
The refusal served only to make Duchovny all the more determined, and he has now appeared twice, giving as good as he received on both occasions. Duchovny likens the Stern experience to a form of Russian roulette - the thrill comes in knowing that it could all go disastrously wrong.
"It's exciting because people are always trying to control the world that I'm in," he says. "It's insulated. I'm always well-dressed when I see people, I've always shaved, I'm always controlled to look and be at my best, and when you do something like Howard Stern anything, anything at all, can happen. I like that."
That Duchovny should need this occasional burst of control-free adrenalin - he has also appeared, sending himself up, on the wonderful spoof talk show, Larry Sanders - comes as no surprise when you meet the man himself.
He has often complained that after years (often working 14 hours a day, six days a week and ten months a year) of playing the same character, he needs new creative stimulation and challenges. A one-on-one with the likes of Stern is an interesting diversion.
These days, of course, Duchovny can pick and choose the chat shows he wants to appear on. The X-Files has grown from a cult hit into an international success in the five years since its creation, turning Duchovny and his co-star Gillian Anderson (who plays his partner Dana Scully) into huge stars.
Over several series, The X-Files has skilfully woven together an increasingly intricate web of conspiracy theories - mostly connected with governments covering up evidence of alien abductions - and expertly fed the nightmares of its diehard fans, known as X-philes.
The $60 million movie version of the show, released in this country on Friday, is another landmark. The trick for the X-Files team was to produce a film that was not only a companion to the series, with references to previous stories and characters that have featured on TV, but also to make a film which would stand alone and draw in moviegoers who have not seen the show. In short, it had to be cinema rather than TV. Duchovny admits that it was a fine line to tread but believes that they have pulled it off.
"It's supposed to be out there competing with Armageddon and Godzilla and that kind of theatregoer wants bang for the buck," he says. "All that stuff - making the alien look wonderful, shooting on a glacier, explosions - is the spectacle and a huge concern for the people having to do it, but fortunately I have nothing to do with that side of it. For me the biggest concern as an actor was how to play a part that I've been playing for five years - and introduce him at the same time. It was an interesting challenge and kind of energising, because it sent me back to the beginning, rediscovering all those things about the character that I liked in the first place. All the dangers of making this movie are only apparent now that we have succeeded. I'd always thought we'd make a movie and it would be great. We know how to make the TV series and we tell great stories and we have good characters, so why not?
"But it's only now, doing interviews, that I fully appreciate all the pitfalls. Not only could the movie have bombed and therefore tarnished the champion status of a great TV show, it could have been totally incomprehensible to people who don't know the show."
Born and raised in New York, Duchovny grew up in an academic environment. "I had no interest in acting as a child," he recalls. "I always had more fun playing basketball, baseball, tennis, anything. I was good at ball sports, I wasn't particularly fast or strong but I had good hand-to-eye co-ordination."
He attended Princeton University and then received his Masters degree in English Literature from Yale, where he first began to act. "There were a lot of actors there and I thought those people were having fun the way that I'd had fun playing sport. It looked like a team sport to me; they were getting together to make something work.
"I didn't think of it as a career at that stage. Actually I wanted to write for the stage and movies and I wanted to learn more about acting in order to write better. I thought I would understand good dialogue if I got to speak it. It's weird the way you kind of back into things . . ."
During a summer break from Yale, Duchovny returned to New York and was offered a beer commercial being directed by a friend. He needed the money and accepted; an agent saw the commercial, and offered to represent him on condition he took formal acting lessons.
"All the reasons I had for getting into acting were so mercenary - I wanted to have fun and make some money. But once I started classes I realised it was something I could enjoy on a spiritual and emotional level. In those classes you get to scream and laugh and cry and I guess because I'd come from a strict academic environment it was really liberating.
"You can do the most powerful things and not have to pay for it - you can sleep with your neighbour's wife or kill someone and you don't have to get beaten up for it or go to jail."
After college Duchovny moved to Los Angeles and began to build a career without exactly setting Hollywood on fire. He appeared in such diverse films as the children's movie Beethoven, as a greedy yuppie, and in Kalifornia, as a man who unwittingly hooks up with a serial killer (Brad Pitt). He is probably best remembered for his role as the transvestite detective Dennis/Denise in David Lynch's offbeat Twin Peaks.
When he was offered The X-Files in 1993 he hoped that the show would either be a huge success or flop and be axed very quickly so that he could move on. He suspected the latter would be the case. "I don't think anyone thought it was going to be huge. It wasn't on one of the big networks - ABC, NBC or CBS - it was shown on the great pretender, Fox. And we were doing a show about aliens, which seemed silly. Chris Carter, who created the show, had never done anything, Gillian Anderson hadn't done anything and no one was waiting for what I was going to do next. So none of us were anticipated in any way."
Instead, filmed entirely in and around Vancouver, where production costs are cheaper than Los Angeles, the show proved it could win ratings against all the odds. It broke viewing records in America and won a clutch of Emmys.
Last year, Duchovny and Anderson campaigned for the show to be relocated to Los Angeles and the sixth series is currently in production there. For the actor, it means that he can be at home with his wife, the actress Tea Leoni, and that, he says, has made a huge difference to the quality of his life.
"I wanted to move to LA before I was married, but after it there was no question, it had to happen," he says. "I want to play other parts, but there is something comforting in knowing how to play this character, getting up in the morning and kissing the wife goodbye, going to work and doing your job. For the moment, it's fine, it really is."