During the 1980s, when Mark Millar was a schoolboy in staunchly Catholic, working-class Castlereagh, near Glasgow, being a comic-books fan was not exactly a socially acceptable activity. This was long before Christopher Nolan, Bryan Singer and Sam Raimi made it cool to like Batman, Superman or Spider-Man. But Millar and his friends nonetheless practiced their obsession in private. So committed were they to the cause of comics, in fact, that they lifted weights in the gym, trained in tae kwon do and even designed their own costumes to prepare for a future as a team of masked vigilantes. "For about six months," says Millar, now 37, "it was a serious career option."
Instead, he says, his friends became doctors, policemen or career criminals, while Millar himself ended up as Britain's biggest-selling comic-book writer. Recently, however, he returned to his teenage self to craft Kick-Ass, the graphic (in every sense) tale of high school student Dave Lizewski, who decides – despite his total lack of special powers or ass-kicking qualifications – to don a green wetsuit and fight crime. Lizewski, who becomes a YouTube star and christens his alter ego Kick-Ass, soon discovers that he's not alone: among his fellow amateur crime-fighters is an 11-year-old ninja named Hit Girl, an instant icon who could do with having her mouth washed out with soap.
The final issue of Kick-Ass has just hit the shelves and will probably, like the previous seven issues, outsell Spider-Man. Thanks to Millar's special relationship with the director Matthew Vaughn, a movie is due in cinemas just two months from now.
"There's never been a superhero comic set in the real world," Millar insists. "Watchmen begins in the real world, but by page 20 there's still a giant blue guy walking around. Even Batman has bullet-proof morphing cloaks."
Lizewski, too, is a more recognisable human being than his predecessors. "You can draw a straight line from the golden age of comics to Kick-Ass," says Millar. "In the 1930s, you had the one-dimensional billionaire playboy, Bruce Wayne. You didn't even know what his favourite drink was. In the Sixties, Stan Lee re-invented superheroes and gave them a second dimension, so you have an alcoholic hero like Tony Stark [aka Iron Man], or a hero who can't pay his bills and worries about his schoolwork, like Peter Parker [aka Spider-Man].
"Dave Lizewski is a three-dimensional hero, a guy who plays World of Warcraft every night and whacks off to internet porn, just like a normal person. Over 70 years there's been a gradual drift to realism, and we're now showing superheroes as real people for the first time."
Millar was inspired to follow his instincts into the comic-book industry after meeting his hero, Alan Moore – the creator of Watchmen – in the mid-80s. Both of Millar's parents had died before he could graduate from Glasgow University, so he dropped out for lack of funds and eventually found himself working at 2000AD, the British stable that bred Moore and most of the country's top comic talent. By 1994, his work had drawn the eye of American publishers, and he began storylining top titles for DC, and later Marvel.
Like Moore, Millar developed a reputation for brilliant subversion of the superhero genre. He wrote the first gay kiss between male superheroes. He created Superman: Red Son about a world in which Kal-El fell to Earth not in Smallville, but in Soviet Russia, and became a socialist icon. His recent title, War Heroes, is set in a future where the war in Iraq has dragged on for decades and the struggling US military has begun to attract volunteers by offering to give them superpowers with which to fight their enemies.
Unlike the reclusive Moore, however, Millar is comfortable with the attentions of Hollywood. Moore's wonderful books have been made into almost uniformly turgid films: V for Vendetta, The League of Extraordinary Gentlemen, Watchmen. Millar has been somewhat luckier: before Kick-Ass came Wanted, his top-selling 2003 title that became a $340m-grossing movie starring Angelina Jolie and James McAvoy, directed by Kazakhstan's surreal action specialist Timur Bekmambetov.
"Most of us that work in comics are read by a niche audience,"says Millar, "so if we go to the pub nobody's going to take the piss out of us for our book not working out very well. But if a film sucks everybody is going to know. League of Extraordinary Gentlemen is an amazing book, but people's perception might be a rubbish film. Alan's excellent work hasn't translated to the screen and he must be slightly embarrassed. If I hadn't been lucky with Wanted and Kick-Ass, I'd probably feel the same."
Millar is also working in a new world, where superhero films frequently account for the better part of every movie studio's balance sheet – meaning that the geeks who once surreptitiously passed comic books to one another under their desks have inherited the Earth. "Stan Lee always says that in the 1970s, when he was trying to get TV shows off the ground, nobody would look at them because they were comic books. Nowadays there's no struggle; you write a comic and you can get a meeting with Spielberg."
As easy as it may be to get that meeting, getting your idea all the way to the screen can be more of a challenge. Kick-Ass is a case in point. "One day," says Millar, "Peter Biskind is going to write a book about what Matthew Vaughn went through to get this film made."
Millar and Vaughn met three years ago through their mutual friend, screenwriter Jane Goldman (wife of comics aficionado Jonathan Ross). "Vaughn was going to film another book of mine, but I told him I was halfway through writing Kick-Ass and he really liked the sound of it. So he wrote a first draft, which Jane polished. When I read it, I thought it was the Pulp Fiction of superhero films. We were all so pleased with ourselves. Then Vaughn sent it to the seven major studios and they all said: 'We hate it. It breaks every rule about what makes a superhero film work'.
"We got seven rejections within 24 hours of sending it out. One of the studios said they'd consider it, but only if we made Hit Girl 19."
Instead of compromising, Vaughn decided to raise the necessary $50m himself and make the movie independently. Eighteen months later, he presented footage from the completed film to a rapt audience at the San Diego Comic Convention and the same studios who'd rejected the screenplay outright found themselves in a bidding war for the finished product.
What makes this all the sweeter for Millar is that Kick-Ass, like Wanted, comes from his own creator-owned line of comic books, Millarworld. Wanted's one million English-language sales made it the highest-selling creator-owned comic of the decade. Kick-Ass has the potential to surpass that – as might some of the other 13 or so books that Millar has in various stages of development. Millarworld's success is such that its CEO can spend half of each year working for Marvel, on prestige titles like Spider-Man, X-Men and Fantastic Four, and half the year working for himself. "This way I can satisfy both halves of my personality," he says. "I can create something brand new, but I can also please the superhero fan I used to be when I was a kid."
'Kick-Ass' and 'Kick-Ass: Creating the Comic, Making the Movie' are available from Titan Books. The movie 'Kick-Ass' is out on 2 April