Brian Cox: The god of monsters

With roles such as Goering, Hannibal Lecter and now an ex-Marine who preys on boys, Brian Cox is clearly not afraid of playing baddies. As he tells Robert Hanks, we're all brothers under the skin

Before we settle down to talk properly, Brian Cox leafs through a tabloid set out on the table in the hotel bar where we meet, checking what it has to say about Celebrity Big Brother. Not usually his sort of thing, but he is curious because last night he met Amanda Holden, wife of Les Dennis, one of the show's current victims; and he talks sympathetically about the misery of a life lived entirely in the public eye.

This strikes me as a slightly incongruous comment from somebody who is not only one of our finest living actors, but also, according to his CV, "the most prolific actor of his generation" – his entry in the Internet Movie Database lists 24 films or mini-series since the beginning of 2000 (not to mention a turn in Frasier as Daphne's dad, which earned him an Emmy nomination). Isn't he in the public eye?

But half a second's consideration and it's obvious how wrong this is. For a start, while Cox is a sensational and charismatic leading man in the theatre, on screen he is usually confined to supporting roles. And in public, he doesn't invite attention: I had a little difficulty spotting him when he arrived, what with glasses hiding the heavy-lidded eyes and a beard disguising the wide, sensuous gap of a mouth. He is also a lot smaller than I had expected – they always are, I know, but more surprising given Cox's titanic presence on stage, the sense of real, flesh-and-blood menace he can bring to a part. In Michael Cuesta's film L.I.E. (see Anthony Quinn's review, page 9), the excuse for this interview, he even plays somebody called Big John.

The film takes its title from the Long Island Expressway - an acronym so tempting you can only wonder why nobody has made a film about it before now. The protagonist is Howie Bitzer, a sensitive adolescent grieving for his mother (killed on the LIE), alienated from his father, groping for his sexuality – a prime target for John ("Everyone calls me Big John") Harrigan. Harrigan is the life and soul of every party, chummy with all the local cops; he is also a predatory pederast.

The surprisingly warm relationship that develops between Howie and John has caused some contention in the US, which probably didn't help it at the box office. The film has garnered a number of gongs and statuettes though, including a couple for Cox personally, and several gay and lesbian film awards. Oddly, the press material goes along with the notion that L.I.E. is a gay film, though Howie's sexuality struck me as unresolved. Cox agrees heartily: "It's been propagandised. And, of course, that's what happens to any kind of – what's the word? – activists, particularly in relationship to homosexuality, will always grab on to that and say, 'Well, it's about this boy coming to terms with being gay'. That's not the point. It isn't about that, it's about sexuality."

He argues that Howie's view of sexuality is temporarily deranged by the death of his mother, and his father's relationship with a bimbo. "The only person who's truly gay in the film is John. But even John says 'I like women.'"

Cox clearly relishes this ambiguity in Big John, and he takes risks with the character that few actors would dare. He doesn't tone down John's monstrous side – the most chilling sequence in the film has John driving through Long Island, watching the local boys, and sniffing a piece of denim torn off Howie's jeans, like a dog. But as the film continues, you begin to find yourself rather taken by this man, even identifying with him.

This is nothing new for Cox, who has played plenty of distressingly human monsters before now. His breakthrough on stage in Britain came in 1987, playing Titus Andronicus at the RSC – chuckling gleefully as he served up child-pie to the children's mother. The previous year he was the first actor to play Hannibal Lecter – Lecktor, it was spelled back then – in Michael Mann's film Manhunter. In 2000, he played Goering in the TV mini-series Nuremberg, winning an Emmy and getting Golden Globe and Screen Actors Guild nominations. Is he attracted to playing monsters?

The answer is a qualified yes: the qualification being that "we're all brothers and sisters under the skin. And that's what's unacceptable, that's why we demonise people – because it distances us." It is imperative to empathise, he says, though not to sympathise, because only by understanding people can you forgive them, and "in order for humanity to move on, you have to be able to forgive",

He is intrigued by Harold Shipman: "At the end of the day, to everybody he seemed the sweetest man, the nicest doctor, but in the darkness of those rooms... he was quite mad, he'd gone over the edge. And it was something to do with the smell of impending death, all kinds of chemicals at work that triggered off his state. The vulnerability, something about elderly vulnerability..."

A colleague from the theatre told me that what is exciting about working with Cox is that he keeps looking for new challenges. His restlessness and his curiosity about people is blatant. He starts talking about a man he heard on the radio earlier that day, who had mercy-killed his terminally ill partner: the man had thought this secret was a burden; but when he finally confessed, he felt not relief but loss – his secret had been taken away. Cox gets very excited: "That is such an extraordinary human reaction to something, and that – to me – you go: 'I wanna play that.'"

This curiosity can't, you feel, be slaked by his Hollywood career, which has involved a good deal of middle-rank schlock such as The Long Kiss Goodnight and The Bourne Identity. Naturally, he says that theatre is where the excitement is, but adds "I'm not a monk of the theatre." And film has advantages: "You know what the problems are with films – you know the black hats and the white hats. You don't always know that in the theatre. The theatre is really full of much more dubious people."

In any case, he has rent to pay on his pad in LA, along with a house in London and a 10-month-old son, Orson, to support. He is not remotely embarrassed about doing films for money: "The reality is, it helps if you do films that make a lot of money... It means nothing in terms of how good an actor you are, but it does mean something in terms of the fact that you'll get employed again." He mentions the film Super Troopers, released here a few weeks ago to pretty much universal derision: apparently, one reviewer said, apropos of Cox, something along the lines of "Well, if he needed the money, we'd have had a whip-round for him." Cox replies: "Well, the thing is, I did that as an independent movie, I did it for no money at all. I did it because it was this young comedy team, and I think a young comedy team should get as much of a break as somebody like Michael Cuesta.

"And that's what I try and do, I try and do as many successful films that pay the rent, films that kind of guarantee my credibility, in order to do films such as L.I.E."

His credibility doesn't seem in doubt: the next few months will see him in Spike Jonze's Adaptation, Spike Lee's 25th Hour, and X-Men 2. What attracts him, apart from the money, is the possibility film offers of tracing an inner journey. This puzzles me: if it is all inwards, how is it expressed? My puzzlement apparently puts me on a par with most directors: "They think it's some sort of mystery. They go, 'Less, more, less, more.' And then they come up and say, 'How did you do that?' and you go, 'Well it's very simple really', and of course it isn't, it's quite complicated and it's years of practice."

With Big John Harrigan in L.I.E., "the acting trap is to say, 'His private life is the truth and his public life is false, so that in public he is fake.' I reversed that thing: I said, 'Really, in public, that's who John is. In private, it's much more difficult, he's much more fake.' He would like his private to be like his public life, because then it wouldn't be as messy. And it's not fake, it's real."

This still doesn't solve the puzzle for me: I still don't understand how you go about putting that truth or lack of truth on screen. Cox says: "Technically, you have more fluency in the public scenes, any obstacle that comes up, you immediately flow over it. Privately, flowing stops – so the current comes to a barrier and it has to find another outlet. These things are very quick, they're very fast, they're almost seamless, you can't really see them." He accompanies this with hand gestures, and it leaves me feeling distinctly less baffled.

Talking to Brian Cox you get the refreshing sense of finding exactly what you expect: a quick, generous mind, lots of energy and a rare willingness to articulate what he does. I still thought he'd be taller, though.