Norman Cook, aka Fatboy Slim, has chosen his alter-ego wisely. The skinny DJ from Brighton has been responsible for some of dance music's biggest, phattest beats, and whenever he remixes a track, he adds just enough weight to make the floor vibrate. The paradoxical nature of the name suits him too - as a one-time member of The Housemartins, Cook once traded in guitar-jangling indie pop, and his current, club-friendly persona is at polar opposites to the fey, insipid style of his former Hull comrades. He didn't become Fatboy Slim overnight, however: first, he topped the charts in 1990 as Beats International with the classic Dub Be Good To Me, then got on an advertising tip with Freak Power, whose Tune In, Turn On, Drop Out single was hip for a while. Cook is still working closely with the acid-funk collective, but he can't seem to shake those pseudonyms - in the past couple of years he has scored underground hits under the monickers of Pizzaman and The Mighty Dub Katz. But Fatboy Slim is the name by which Norman Cook is destined to become a legend, and right now it's a perfect fit for the man who has already been dubbed the godfather of Big Beat. The larger-than-life sound which is the imprimatur on a Fatboy Slim record has become much sought-after for many would-be club classics. Take the recent re-release of Wildchild's Renegade Master, which went straight into the Top Five, for instance - that's the Fatboy's Old Skool remix which gets them going wild on the dancefloor. Seen the Lucozade advert lately? That's the Slimster's reworking of Jean Jacques Perry's EVA. Can't wait for the new version of Cornershop's Brimful Of Asha, due out this week? Of course you can't, because the boy Slim has tweaked this Hindiindie tune and filled it full of Eastern promise. But the remixing is only half the story. As Fatboy Slim, Cook has found himself at the centre of the Big Beat storm, and his DJ slots at Heavenly Social in London and Big Beat Boutique in his home town of Brighton have become the stuff of folklore. He may not have invented Big Beat, but he was certainly there at its onset, and no-one better typifies the movement's diverse delving into rock, hip-hop and old funk. Bands such as The Chemical Brothers and The Prodigy have brought Big Beat out into the arenas, while Bentley Rhythm Ace and Lo-Fidelity Allstars have put their own twist on it, but Fatboy Slim has pulled its many threads together with his all-embracing approach.

His debut album, Better Living Through Chemistry, is the perfect pad-wrecking party record, containing such essential ass-kicking tunes as Everybody Needs A 303, Santa Cruz and Going Out Of My Head. It's not quite the intellectual equal of a David Holmes, DJ Shadow or Roni Size album, but pound for pound it delivers on the big fun scale. Cook is loath to take credit for helping to originate Big Beat, but he will reveal the name of the man who coined the term: his flatmate, Gareth. He also name-checks many other movers and shakers in the movement, including Tom and Ed, aka The Chemical Brothers, Jon Carter of Monkey Mafia, and Richard Fearless of Death In Vegas. Not to forget US West Coast pioneers such as DJ Icy and the Bassbin Twin. "We used to call it West Coast Breakbeat Sound," Cook says. "The whole thing is an amalgamation of tons of other stuff, so I don't think anyone really started it, it was just this nebulous thing."

Nebulous in theory, but in reality the sound is massive enough to cause serious structural damage to your dancehall/ballroom/bedsit. If you saw the Chemical Brothers at the Point last November, you'll have some idea of its awesome, shuddering power.

Times are not looking lean for Fatboy Slim - his remixing skills are in such demand he's been burning the calories in the studio at both ends. The workload has become so heavy, in fact, that he's had to turn down some serious requests; U2 and Aerosmith are among the many top artists who have had the Brighton boy's door closed in their face.

But pop music is a fickle mistress, and it has dropped many a rock star out of vogue and out of the running. Is the DJ/remixer also subject to the vagaries of changing tastes? "Oh, yeah, definitely. I've gone out of fashion a couple of times in my career! And it's not just a fashion thing; there are times when you lose it. It happens to all musicians - for every Life On Mars there's a Laughing Gnome, d'you know what I mean?"

Is that why he uses so many different pseudonyms, to avoid being singled out by the fickle finger of fame? "Well, a lot of it is that tons of stuff just comes out of my head, so I need a lot of outlets for it. But half of it was because I'd gone out of fashion. If I'd told everyone from the off that Fatboy Slim was me, nobody would have liked it, they'd have gone, oh, no, not Norman again. Even The Face magazine put Better Living Through Chemistry in their albums of the month, and then they found out it was me, and they said `if we'd known it was Norman we wouldn't even have listened to it'. "Another reason for all the pseudonyms is so I can do different types of music - like The Mighty Dub Katz is my outlet for house music. And I had the Pizzaman pseudonym because I was still contracted to Island Records, and I could only release independent singles under a different name, for legal reasons."

Does juggling all these different stage names ever give Norman Cook an identity crisis?

"Oh no, I love it! It's a laugh. But sometimes when I go and DJ, I'm not sure if they've booked me because of the Dub Katz, Pizzaman or Fatboy Slim, so I don't know whether I'm supposed to be playing a cheesy house set or a Big Beat set."

Nowadays, Cook spends less time on the dancefloor and more hours in his home studio, writing, recording and remixing. "I only play on average once a week, or do a Friday and Saturday one week, then take the next week off. I have to really limit my DJ work, because otherwise I wouldn't get any other work done. I do have a fondness for alcohol and narcotics, and when I've finished playing, I don't tend to go to bed straight afterwards. If I played every weekend, I'd never get any work done till Wednesday, frankly."

Fatboy Slim plays Galway's GPO Club tomorrow at 11 p.m.