Col Needham is 46 and lives in Frampton Cotterell, a small village eight miles outside Bristol. He is bright-eyed, wears glasses and has the face of a beaming baby. Despite nearly three decades of living in the West Country, he still sounds Mancs. Every Tuesday lunchtime, he and his wife Karen go on a date to their local Odeon. At the pub, he has a small glass of white and goes easy on the nuts. He laughs a little more than average – every fourth or fifth statement is broken by a big giggle – but other than that, he is not an obvious headturner.

Needham is also the most powerful Brit in Hollywood – by miles, by millions. He is our Harvey Weinstein. More than that, he's our Mark Zuckerberg, too: the Steve Jobs of south Glos. That's because, 23 years ago, Needham created the Internet Movie Database – a compendium of film and TV credits, connections, goofs and trivia. At first it was a cottage hobby: run from his semi in Stoke Gifford (four miles from Frampton) while he was working for Hewlett Packard and the internet was still in its infancy. But as the web grew, the potential of a site whose raison d'etre was connectivity became plain. IMDb quickly became the market leader in its field. It still is: when it comes to online film coverage, no one can touch IMDb. The site is now among the 50 most popular websites in the world, with 160 million monthly unique users.

Needham sold to Amazon in 1998, but retained the reins. Today, not only does he pave a path for film fans, he also keeps the people who actually make movies on a tight leash – through subscription site IMDbPro (which, among other things, gauges every star's current wattage) and sister sites such as Box Office Mojo (which tracks profits and losses). When he met Steven Spielberg at the Oscars in February, it was the director who grabbed hands and paid lip service first.

That, says Needham, was especially thrilling: his first trip to the cinema was to see Jaws, aged eight, with his mum. Afterwards, he recalls, "I was scared of even going in a swimming pool, let alone the sea." He was hooked, hungry for all the movies he could consume. Six years later, in 1981, came his first experience of home entertainment: he was loaned a VHS of Alien and watched it every day for a fortnight. Then, in April 1989, he took his first trip to the US: he checked into his hotel, drove to the nearest video store and rented A Clockwork Orange, which was banned in the UK at the time. "My secret plan … well, my broadly public plan" – he pauses for a happy laugh – "is to make everyone love film and TV as much as I do. Growing up, we went to the cinema quite a lot. But it wasn't until I got online that I started being able to discuss films with other people."

Why has the kind of engagement IMDb allows proved so popular? "Cinema is one of these unique industries where people come together to work and then they scatter," he says. "It seems to appeal to people to make connections." But why? He is briefly silent. "Gosh, I don't know. I guess it's kind of like High Fidelity: you want more. The human brain likes to make connections. Somebody spots a connection between two things. This prop always appears in their films, the roars in The Lion King are actually those of a tiger. You want to share that knowledge. And IMDb is a good platform."

Although Needham himself is now embedded in the film industry, he succeeds because he is cut from the same cloth as his audience. He's fresh from a Q&A session with education charity Filmclub and sports a canary-yellow IMDb badge on his blazer and another on his shirt, lest he need to remove a layer. If the shirt comes off, he says, there is no IMDb tattoo. But he doesn't need one: he is a living, breathing posterboy for his product: pick apart IMDb's coding and it'd read like Needham DNA.

He has seen 8,254 films, a figure he can be certain of as he has rated them all on his own user profile page. These, as well as the talkboards and user-generated lists (Needham's include 10 Roman Empire Movies and his Top 100 Comedies Up To 1960), are not only commercially lucrative, they are what turn a huge data hub into something with a little more spin. IMDb offers not only reams of information but a means of navigating it, too.

"It is definitely a more complex world now," he says. "I watched Alien 14 times when I was 14 because that's all I could watch. It was like, 'Wow! A film I can watch over and over!' Now there is this vast opportunity. I view audience choice as a good thing. The more things there are for people to see, the more chance they're going to find something to relate to."

To have both served up a glut and made it digestible is quite a feat. But perhaps the most remarkable thing about Needham's creation is that, by being the default destination for cinema-goers, he can now influence the movies made for their consumption. Costing $125 a year, IMDbPro provides fuller contact details for talent, as well as their upcoming projects; and, crucially, it boasts the Starmeter, which ranks actors, directors, writers and producers in order of desirability. The algorithm is simple: how many views has their IMDb profile page had that week? As Needham explains, the industry can use this info to invest wisely: "You can catch a rising star while they're at cheaper prices, or you can find people who are still great but on the way down." Producers eager to cast the lead in Twilight reportedly came up with Robert Pattinson by ordering a flunky to provide a list of everyone with a certain Starmeter rating who had also been in a Harry Potter film.

Cinema, already a market forces artform, has had its creative process democratised. Interesting wrinkles surface from this collision of consumer destination and industry tool. Last year, a woman took the company to court, claiming that by revealing her real age on IMDbPro, her employability as an actor had been diminished. IMDb won, and Needham is now fairly blase about the issue: "Our aim is to be as complete and accurate as possible. We have a strict policy to never remove accurate information. The second you start to compromise on that … "

He drains his glass, prepares to catch the train back to Bristol, where IMDb is still based, with offices in Seattle and Santa Monica. We talk wine for a while: Needham likens rare films to vintage bottles. His own favourite stars are Cary Grant and Katharine Hepburn, though he's intentionally holding back on seeing some of their early work. "Every now and again, I'll get out a vintage 1936 Cary Grant and I'll say to my wife, 'Shall we uncork this?'" But he tries to resist. "When you hit that point where you've seen everything on a star's IMDb filmography page – well, where do you go next?"