Zack Snyder, the director of 300 and Watchmen, brings his adman sensibilities and knack for CGI mayhem to a peculiar family fantasy about warring owls, writes DONALD CLARKE

ZACK SNYDER seems like a nice enough man. Casually dressed, looking a decade younger than his 44 years, he lounges nonchalantly on a sofa in London’s Dorchester hotel. He has a decent sense of humour. He is markedly unpretentious (to a fault, perhaps). But you really wouldn’t take him for one of the decade’s most influential directors.

An overstatement? Well, just think how often you see images influenced by 300, Snyder's sword-and-disembowelment epic. It turns up in haemorrhoid commercials. A thousand billboards have referenced the poster. Spartacus: Blood and Sand, the recent, hilariously violent TV series, owes everything to Snyder's amalgam of shouting Scotsmen and computer-generated mayhem.

“Oh, yeah. I met those guys from that show recently,” he laughs. “They were like, ‘are you mad with us?’ And I said, ‘aww, no’. They kind of said they were sorry. How can you be mad when somebody is like that?”

Snyder followed up 300with Watchmen, a slavish adaptation of Alan Moore's iconic comic book, and has now delivered a profoundly peculiar family animation called Legend of the Guardians: The Owls of Ga'Hoole.Based on a popular children's book by Kathryn Lasky, the film comes across like a blend of Watership Down and Lord of the Rings. Something to do with a bunch of nice owls who fall foul of evil owls led by Queen Helen Mirren, Legends of the Guardian, like Snyder's previous two films, features some nifty computer-generated imagery.

“I was in Animal Logic studios – the guys behind the animation – a few years ago, and I saw this artwork they had done on the project. ‘Oh, that’s some animated thing you wouldn’t be interested in,’ they said. But I read the books and they were cool. So I got hooked.”

The story says a lot about the director’s sensibilities. A film-mad kid who was playing with an 8mm camera before he could walk, Snyder trained at the Art Center College of Design in Pasadena alongside such developing titans as Michael Bay. After leaving the college, he, like Bay, spent many years working in TV commercials. It is unfair to stereotype directors who come from such a background, but it remains interesting that it was an image, rather than a story or a theme, that drew Snyder to the owls.

How does he react when critics claim that Snyder (and Bay) make the sort of movies you’d expect from commercials directors?

“I love that. I think it’s great. Movies are pictures. Michael makes slicker images than I do. But images have to be awesome. I love those older guys who came from commercials: Adrian Lyne, Ridley Scott. That is very much the cloth that I was cut from.”

You will have noticed a key phrase there: "images have to be awesome." That could be the mantra of the new movement. Few punters emerged from 300raving about the dialogue or the historical analysis.

Before he got around to reinventing our attitudes to the ancient world, Snyder dared to direct a remake of George Romero's great zombie thriller Dawn of the Dead . To most observers' surprise, his debut worked out pretty well. It's not the most subtle picture, but it has an energy all its own.

The director, who has six children, remembers the strain of trying to start a career while raising a large family. "That was hard. There is no trick to it. Or, rather, the trick is simply that certain things don't get done. My daughter Olivia is 17. When she first saw Dawn of the Dead she said, 'You missed my childhood for this?' She's got a good sense of humour."

Nobody expected 300to be such a hit. Released early in the year, to that point regarded as a slack period for blockbusters, the film achieved a huge opening weekend and went on to gross nearly $500 million. Animating Frank Miller's comic book version of the Battle of Thermopylae, 300not only altered the studios' attitude to the release calendar, it made a star of Gerard Butler. Everywhere he goes, fans now bellow his key line – "this is Sparta!" – in a Scottish accent.

“Yes, we gave the world a catchphrase,” Snyder agrees. “All the Spartans are English or Scottish in the film.”

He rolls his vowels and adopts a vaguely Butleresque timbre. “Sparrrrrta! Everyone now thinks that’s how you pronounce Sparta. We’ve changed the way the word is said. But that film also was a move on in terms of pop culture. The tools were the same as before. But we just allowed the movie to become self-aware.”

300was so darn popular that it finally enabled Watchmento make it on to the big screen. The popular graphic novel, written by Alan Moore and illustrated by Dave Gibbons, had been knocked around the development schedule ever since it emerged in 1986. For many years, Terry Gilliam was pencilled in to direct. Then Darren Aronofsky was on board. With such exalted names being bandied about, it was not altogether surprising that the announcement of Snyder's appointment was greeted with some muttering.

The film performed only modestly well and generated genuinely mixed responses. The most fanatical Watchmenaddicts felt that, by leaving out one or two key characters, Snyder had delivered a travesty. More sober observers argued that the film-makers had been far too faithful to the source. In fact, the film plays a little like an animated storyboard.

“The script I inherited was set today. It was all about the war on terror and so on. I said no. We are going to shoot the comic book. I can fight any purist on whether the film is not close enough. I can crush those people. I am a zealot. If you gave me the Bible to shoot, I would shoot the Bible. Here is the holy text.”

At any rate, the slightly sluggish performance of Watchmendid nothing to hinder Snyder's ascent. Just last week, the trade papers were buzzing with the news that he is to direct the next Superman movie. The film, conceived by Christopher Nolan and David Goyer, who so successfully rebooted Batman, remains something of a mystery. Will it follow on from 2006's somewhat under-appreciated Superman Returns?

“I can’t tell you much, other than I am a big fan of the character,” he says. “I am psyched as hell to work on it. He is such an iconographic character. The only thing I can tell you is that it’s not a continuation of the last one. We are going in another direction. We had studied, philosophical conversations about the direction the story is to go.”

We should expect nothing else. Before Superman emerges, we will get another chance to see the Snyder flash in action. Early next year, the director will give us a fantasy drama called Sucker Punch. What can we expect? "Oh, awesomeness," he says. "Yeah, general awesomeness will abound." You have been warned.

• Legend of the Guardians: The Owls of Ga'Hooleopens next Friday