It can be a little difficult to explain Neil Gaiman to the uninitiated, but there's solace to be taken in the fact that he has similar difficulties himself. "There's that point where I meet people and they ask what I do, and I say, 'I write'. So they say, 'What do you write?' and I start sounding shifty because I say, 'Oh, all sorts of stuff'. And they say 'Adult books, children's book, short stories, movies, TV, journalism, songs, poetry?' And I just go, 'Yes, all of that,' and it sounds pathetic, I can hear it coming out in my voice. Nobody's going to believe you. At that point you're going, 'Well, I've got these awards…' I would have loved to have been a novelist, just so I could say I'm a novelist, but I'm not."

He's being both a little disingenuous and too modest. For one thing his last two novels, American Gods and Anansi Boys, both rocketed to the top of the New York Times bestseller lists. That's enough success for anybody to start calling themselves a novelist if they so desire, but Gaiman has no such inclination and it's probably at least part of the reason he remains more of a cult concern than a household name. It's not that he necessarily rages against being pigeonholed, more that he just follows his muse wherever it goes.

Born in Hampshire, England, in 1960, he was a journalist in his early days and regularly found himself interviewing extremely successful, yet frustrated, writers. Long after the interview was over they'd talk about novels they wanted to write but their publishers wouldn't let them. "It crystallised something for me, long before I'd ever written a novel," Gaiman explains. "I just thought how I never wanted to do that. I want to be the kind of author who, if I phone up my publisher and tell them my next book is going to be a pornographic cookbook, they'll just say, 'Are you arranging for the photos to be taken or are we going to have to pay for it?'

"I have no understanding of why I should do the same thing over and over again, or do similar things over and over. There was an English publisher who was trying to court me a few years back and wrote a letter to my agent saying that 'Neil's finally gone big with American Gods and I want him as my writer and obviously from now on he's going to have to write books of roughly the same size and topic so that we can grow his audience and turn him into a bestseller author'. And I'm sure she was right. I told my agent not to ever phone her back and went off and did Coraline, 1602 and Beowulf [a children's book, a Marvel comic and a film script for Robert Zemeckis respectively]."

But such a relentlessly eclectic attitude can cause difficulties. "I get a lot of puzzled readers who have been trained by other authors that if you like one thing they've done, you'll like the next cause it's the same kind of thing. There are people out there who'll think that I've gone off, 'cause they read one thing and really like it, then read the next and don't. The people who've been reading my stuff for longer are the ones that go, 'It happens'. You're not expected to like everything I've done."

This approach is heavily influenced by Gaiman having made his name in comics, specifically The Sandman. Famously described by Norman Mailer as "a comic book for intellectuals", it was an epic undertaking. A comic series that started in 1989 and continued for the better part of a decade, by the time it concluded it was outselling Superman. "The glorious thing about comics is that it's a medium that people constantly mistake for a genre. So with Sandman I could do something that was horror here, fantasy there, a couple of issues that were practically mainstream literature, straight historical, or a spy story. I could do all this stuff and nobody batted an eyelid; nobody thought it was particularly odd because it was all comics, which gave me this tremendous freedom, even now."

That freedom informs his latest release, The Graveyard Book, which, with a nod to Rudyard Kipling, concerns an orphan baby that comes to be raised by the ghosts and ghouls of a graveyard, meaning that the main character, named Nobody, isn't scared of things that go bump in the night but has a far more difficult time dealing with the living. It's a children's book, but comes with a guaranteed crossover appeal that has seen it go straight to the top of bestseller lists in America. A film version is already in the works.

"I thought if I'm writing it for kids I want to tell them some true things," says Gaiman. "And you don't want to tell them true things in that dull Richard Dawkins way, of the imagination is wrong and you should accept the world as it is and as all there is. Because where's the fun in that? Where's your magic? I thought I'd rather tell kids that graveyards aren't scary places, they're really rather peaceful. If you have anything to be scared of in a graveyard at night it's walking around on two feet, living and breathing just like you are – it wasn't safely interred in a box 200 years ago. What's nice is that people seem to be reading two different books [depending on their age]. Kids are reading it and saying they wish they could live in a graveyard too, while adults are reading it and seeing a story that's about family and growing up."

Gaiman is particularly proud of the book, perhaps unsurprisingly given that he had the idea for it over 20 years ago and hadn't until now felt he could do the story justice. "I'm usually painfully aware that there was this thing in my head when I sat down to write and how brilliant it was, and then I'm looking at the thing I wrote... I had this perfect, brilliant book, and then I produce this small squat thing that hops and dribbles. And everybody goes, 'Oh that's really lovely', and I'm going 'Yeah, but you should have seen the one I had in my head'. The thing I love best about The Graveyard Book is that it's slightly better than the thing I had in my head."

He's not resting on his laurels though. Up next is a two-part Batman story for DC comics, due in January. Taking on one of the most recognisable characters in the world doesn't faze him, but he doesn't envy Irish author Eoin Colfer his task in writing the new Hitchhiker's Guide to the Galaxy book. Gaiman was a friend of Douglas Adams and had previously turned down a request from the author to write a radio series based on the sequels. "I can't see the point of it at all. Nobody read the Hitchhiker's books to find out what those characters did next. You read them because Douglas could put together a sentence that made you think about the world in a different way. Eoin is a good writer and will write his book with more enthusiasm, more enjoyment and definitely quicker than Douglas would have written a sixth Hitchhiker's book, but it doesn't seem to me to be anything that the universe was lacking."

Something that is lacking from Gaiman's canon though is a non-fiction book following the path travelled by Monkey in the 400-year-old Chinese classic Journey to the West, so obviously that's what he's doing next. It's a typically idiosyncratic choice but, as he puts it himself, "Given the choice between doing something I've done before, and doing something I've never done before and risking making a complete idiot of myself, I will do the something I've never done before." Thankfully it's a lot easier reading him than it is keeping up with him.