A Heroes star leading a far from ordinary teenage life

Hayden Panettiere is the poster girl of hit television show Heroes. The plot of the series about ordinary people who suddenly discover they've got superpowers could almost work as a metaphor for the life of the 18-year-old. Overnight she was thrown into the global limelight by the phenomenal success of the show. Every word and action of this girl from upstate New York became newsworthy, including her wardrobe, the men on her arm and, perhaps more surprisingly, her politics.

In Heroes, which returns to BBC2 tonight, Panettiere plays Claire Bennet, a 15-year-old cheerleader, who, in the first episode, discovered that she could heal instantly from any injury. The indestructible high-school student is forced to hide her ability from her peers and maintain a relationship with her father, a man who is keenly interested in people with special powers.

The first series won plaudits and awards but the start of the second series was met with a backlash when it aired in the US. Fans complained that the show had become lacklustre, the new characters were uninteresting, the trademark episode cliffhangers were noticeable by their absence and the story was unfolding too slowly. Show creator Tim Kring even went on record to apologise for the mis-steps and just as the season got back on track, the writers' strike ensured that the second series only had 11 episodes rather than the expected 24. Arguably it was a blessing in disguise.

However, just as interest in the show was beginning to wane, media interest in Panettiere went into overdrive as it emerged that she was dating her co-star Milo Ventimiglia. The news was met with consternation among her fans, with a consensus that the 12-year age gap between the pair was too large.

The blonde teenager has complained about the judgmental attitude of the criticism, but believes that she is now mature enough to handle it. One of the reasons for this is a holiday to Europe that she took with Ventimiglia and fellow cast members Jack Coleman and Adrian Pasdar: "About five days after I turned 18 [in August 2007] I took off to Europe with them. It was the first time that my mother hasn't travelled with me and we went to Munich, Paris and London. It was such a different experience being on your own and it just changed me dramatically. My mom says that one person walked on that plane and another person walked off."

She talks of having a family at home and a family on set. She describes the cast of Heroes as being her surrogate fathers, brothers and sisters; revealingly, there is no room for a surrogate mother. Her mother is Lesley R Vogel, a former soap actress who put her daughter into her first commercial when she was just 11 months old. At the age of four, Panettiere had landed her first part in a soap, and by the time she was nine she had appeared on Jay Leno's talk show. Aged 10, she was nominated for a Grammy Award for Best Spoken Word Album for Children for A Bug's Life Read-Along. She has sung songs for soundtracks including Bridge to Terabithia, and later this year her debut album is due to be available for download.

It seems that it's impossible not to talk about her wardrobe. When we meet she is wearing a blue Cynthia Rowley dress that, given its length, could easily be mistaken for a T-shirt. Her face is splashed with ready-for-television make-up and her hair is immaculately curled. She looks like the archetypal all-American prom queen. She is being spoken of in the same breath as Lindsay Lohan and Mischa Barton. However, unlike both those stars, who have both been arrested for drink-driving, Panettiere's arrest record is one that she is proud of.

On 31 October 2007, she was part of a group of protesters involved in a confrontation with Japanese fishermen. The group tried to disrupt the annual dolphin hunt in Taiji, Wakayama, by swimming towards dolphins that were being herded to a cove where they could be killed. In the confrontation, Panettiere paddled out on a surfboard before being forced back to shore as the fishermen used their boats' propellers and harpoons to block the protesters. On the beach, television cameras caught the actress in tears before the group of surfers headed straight to Osaka Airport and left the country to avoid arrest by the Japanese police.

The protest established her as the poster girl of the Save the Whales Again! campaign. She recalls: "I was absolutely beside myself the whole time. They wanted to arrest me, but it created such a wonderful stir in America and around the world that it was the biggest step forward we've ever had with the problem. At the end of January, I spent four days in Washington DC visiting the embassies of Japan, Norway and Iceland, the whaling nations. I spoke to the foreign minister of Japan and I think that they've lifted the arrest warrant, because I was at the embassy and that would have been interesting locked in a jail cell below the embassy in DC, but he welcomed me back so unless it's a trap I think I can go back to Japan now."

She recounts the tale with a glint in her eye: "He was so polite, respectful and kind and told me: 'You are the most welcome guest that I've ever had.' I was like, 'Shit, really! Thanks. I don't know how much I believe you, but thanks.' We spoke about how Japan looks at Sea Shepherd as if they are a terrorist organisation, and about how whaling can be stopped."

Whether she will turn out to be the Hanoi Jane of her generation or not, American politicians are as eager as the whaling nations to get her on side. I'm struck by how nonchalant the actress seems as she talks about being tapped by both Barack Obama and Hillary Clinton: "I've had conversations with both of them. Actually, it was with Obama and Chelsea Clinton rather than her mother. The reason I was having meetings with them was to ask about their opinions and views on whaling, which dramatically impacts my opinion on who I vote for." Only just old enough to vote, the actress would not divulge which of the two camps won her over.

The Heroes star is even turning the media infatuation with what she wears into a way of helping save the whales. She has set up a website (www.panettierecloset.com) that sells clothes and accessories from her wardrobe, with the proceeds donated to animal-rights campaigns. When purchasing from the site it will pay to remember that the actress is only 5ft 1in.

Her film career is about to take off, too. She will soon be seen in Fireflies in the Garden, in which she stars alongside Julia Roberts, Ryan Reynolds and Emily Watson. In the family drama, Panettiere appears in the flashback scenes playing the young incarnation of the no-nonsense character that Watson plays in the present. Fireflies' director, Dennis Lee, has no doubt about her star quality, "Hayden is spectacularly talented. People know her through Heroes but she is the real deal. I'd love for people to understand that and not lump her in with her generation of actors who tend, for a lack of a better phrase, to get themselves in trouble. She has her head on straight."

Whether or not she is the most talented actor of her generation is a moot point; what is in no doubt is that she is the most dynamic teenager to have come on to our screens in a long time.

Heroes starts tonight at 9pm on BBC2; Fireflies in the Garden will open later this year

Masi Oka- superHiro

In Heroes, Masi Oka is an office worker who bends time and space. In real life, he's a computer genius who creates special effects for Georges Lucas and Clooney. He could be the biggest geek on earth. He's certainly the most popular, finds Horatia Harrod

The first time that Masi Oka became the face of Asian America was in 1987, when, aged 12, he appeared on the cover of Time, small and blue-shirted, a rucksack slung awkwardly over his shoulder. He's dwarfed by the headline above him: 'Those Asian-American WHIZ KIDS'. He happened to show it to one person and now it's become part of his story (see also: his very high IQ; the fact he still drives a 2000 Honda Accord). But the funny thing is that although he was a clever child who went to a school for the gifted, he was there mainly because his mother knew the photographer.

The second time Oka became the face of Asian America was in 2006, and this time it was less down to luck (although in his self-deprecating way he insists that it was) and more the result of a leap of faith he took six years earlier when he decided to become an actor. The pay-off was huge: a lead role in the NBC series Heroes, the big-budget, ratings-dominating show about ordinary people all over the world discovering that they have superpowers, which airs from Australia to Japan to Germany to South Africa, and whose second season begins this week on BBC2.

What's more, Hiro Nakamura, the time-freezing, time-travelling character Oka plays, has become the fans' favourite, an unlikely sex symbol and object of affection, even more so than the nubile cheerleader Hayden Panettiere and the conventionally handsome Milo Ventimiglia. Oka's internet fan sites show that he hits the part of the brain normally only stimulated by newborn babies and sleepy kittens: they are a babble of delighted gurglings about how 'cute' and 'adorable' he is. None of this was part of Plan A, but, as he tells me as we sit in a garden in Silverlake, Los Angeles, 'I always like to surprise.'

The surprising life of Masi Oka began in Tokyo, and took its first fateful turn when he was six. His mother had already created a family scandal by divorcing Oka's father, and she was bolder still when she decided to take her son and fly off to the United States. 'She gave up pretty much her life for me. She realised that the Japanese education system would stifle me, and she wanted to bring me to America where they would nourish me and let my "academic gifts" expand. She was willing to take all these risks against the recommendations and the wishes of my grandparents.'

The two of them touched down in Los Angeles, and landed up in Van Nuys, a cheap, rough-edged area in the San Fernando Valley. Oka wasn't too fazed by the freeways and palm trees and everything else that made up the new world he'd found himself in; at least not until the first day of school. He was at the Mirman, which is a school for the academically gifted, but the other children weren't exactly sophisticated: 'I remember getting a weird nickname, like Kenickio, I think it was because there was a Japanese bookstore named Kinokuniya; and I realised that people do find it weird that I eat raw fish or rice at lunch and not peanut butter and jelly sandwiches.'

Fortunately, though, the brainy little monsters who clung so spitefully to their sandwiches wouldn't tease their fellow pupils for being clever. At a school for the gifted it isn't so much whether you're going to be a geek, rather what type of geek you're going to be. Oka was a maths geek: 'I did love playing with computers and maths and puzzles. I just loved solving problems, and there's something about trying to figure things out and making things work that was always a big thing with me.' When he finished school, he got into Brown, the Ivy League university in Rhode Island, and his major was in maths and computer science.

The instant associations conjured up by 'maths and computer science major' aren't pretty: a pallid face lit up by the unearthly glare of a computer monitor, gazing intently at numbers, typing furiously, possibly wearing one of those shirt-pocket protectors. Oka wrestled with the stereotype and managed to push it aside. At college he discovered another side to himself. 'I was so focused on the left brain, about being logical, about problem solving, that I wanted to do something that was right brain, to kind of balance myself, to see the world in a different way. So I started doing a lot of theatre, music, performing, singing.' Admittedly, joining the college a cappella group didn't exactly make him the big man on campus (although, he insists, 'we thought we were rock stars'), but getting a bit of 'wiggle room' to reinvent himself was liberating.

The left brain/right brain wiggling didn't stop at Brown. His first job out of college was a covetable position at Industrial Light & Magic, the visual effects company owned by Lucasfilm. What he loved about computer graphics was that 'when you write an algorithm, you can visually see it, so you can show it to a friend and say, hey, check this out. And they say, oh wow, that's cool! You program a database or something, it's an artform in itself. No offence, but if I show it to my mother it's like...' He gives me a glazed look of deathly boredom.

His job, roughly - I think - was to create a system to allow the special-effects artists to create things visually without having to crunch all the numbers to make them happen. Halfway between the physicists and the artists, he could crack asteroids into a million pieces (in Star Wars Episodes I, II and III) or bring waves crashing down onto boats containing George Clooney ( 2000's The Perfect Storm, Oka's big break in the visual-effects community) or Captain Jack Sparrow. He was inspired and happy and his seniors took an interest in him. 'I realised I could stay there for ever, because I really enjoyed what I was doing.' But he didn't stay: 'I realised that when that happens, you need to shake things up.'

In his spare time he had continued to study acting: 'I learnt how to improvise, the skills and tools. And it was so attractive to me because it was technical; comedy in America is very scientific. There is a fine line between art and science, and there is a reason why some things are funny. There are just certain things: a derailment of thought or repetitions, light after heavy, heavy after light. There are so many rules you could use that can work out.'

Armed with his comedy databases, he knew where he wanted to go. At ILM he was working for Hollywood movies. 'But we never really got to experience the Hollywood glitz and the glamour. So for me, I was like: I just want to try Hollywood, just to see what it was like, before I regret not doing it, or before I get too old and can't do it. When you're in your early twenties, you think the world's your oyster and you can do anything you want. So I was very naive.'

It was 2000, a pretty good year for starting something new, and Oka decided to make another momentous journey to Los Angeles. He wasn't travelling as far as his mother had 20 years before - ILM was based in San Francisco, only a few hundred miles up the coast - but he was taking his intelligence, wholesomeness and optimism to a place where none of those things really mattered.

He kept his job with ILM through 'telecommuting', which is not like the travelling through time and space he does as Hiro, but involves telephones and the internet. He managed to keep everything going - the tech work as well as the auditions - but the roles he was getting weren't great: 'Asian man', 'Japanese tourist', 'Japanese pedestrian'. Sometimes the writers actually thought of names for the characters he played - Wonsuk, Deng Wu - but evidently they didn't think very hard. He had a mini-breakthrough when he got a recurring role in Scrubs as Franklyn the lab assistant, but on the whole it was frustrating: 'I realised people weren't writing roles for my type.' Six years after returning to LA, he'd reached a crossroads. When he got the script for Heroes, 'it was my last pilot season as an actor. I was ready to give up acting.'

His agent must have had a heart attack when the script hit the desk. 'It was the first pilot that came to my agents where they were like: we have your pilot?. They were looking for someone fluent in Japanese, who had a comedic background and who had some American television experience.'

Despite the excited flutterings of his agent, Oka was still sceptical - 'I was like: I've been through this.' But as he read the script, he knew it was the one. It was well-written and, more to the point, he had a lot in common with the character of Hiro: 'We're both from Japan. We both felt kind of isolated from society in some senses, thinking that there might be more to our lives. I love manga, he loves comic books, American comics. We're both fluent in Japanese. We both worked cubicle jobs: fortunately I enjoyed mine; Hiro didn't enjoy his too much. And there's an optimism for life. Like Hiro, I do have a childlike curiosity for a lot of things.'

When he told the comedian Sarah Silverman, whose show he'd appeared in, about the part, she tried to put him off. 'That sounds so gay!' she squealed. Fortunately, he didn't listen.

Hiro has become probably the most popular character on the show, quite an achievement when you consider that almost all of his dialogue is subtitled. Amazingly, he didn't appear in the first drafts of creator Tim Kring's script; it was Kring's wife who suggested he add a lighter, comic character to the mix. Kring doesn't speak Japanese, and it shows in the cry of delight that Kring intended to spring from Hiro's lips when he first manages to stop time: 'In the original script Tim wrote "bonsai". On the first day on set, I asked Tim: "Is it OK to change this, because bonsai means little tree."' The word he was looking for was banzai (Americans, doh), and on Oka's advice this eventually became yatta, which has become an unlikely playground catchphrase.

When he's approached by fans, he reckons about half of them address him as Hiro, and half as Masi. The demands of making television programmes in the States, where a season can run to 20 or more episodes, mean that 'television characters tend to be an extension of who you are, versus cinema, because they just don't have time to have you create this character, and you have to wear it for such a long time that you have to be comfortable, so you start to grow into that character and the writers start to write to you. So there has to be a very big part of you that associates with that character.'

Of course he isn't Hiro. Oka may share his basic optimism, but he's more serious and less anarchic than Hiro. When we meet he's tired after a late night/early morning reshoot of some scenes from Get Smart, the spoof starring Steve Carell and Anne Hathaway which is out in August. In the LA apartment where he lives by himself, he's been working hard on writing, too: things he can't discuss because they're being negotiated over (but one is a science fiction series, and he's making forays into romantic comedy, for which he has an unexpected passion). He even does occasional work for ILM. In other words, he doesn't always have time to be as silly as Hiro. Besides, his appearance is low-key: he flattens down the hair that's been shocked into a little quiff by the groomer as soon as the photo shoot is over, and his spectacles and understated outfit make him look fairly nondescript.

He does get recognised all the time, though. 'I have people who recognise me from my back. I mean there's the whole stereotype that all Asians look alike, but people just pinpoint me out of nowhere.' He loves his fans, and can even get a bit gooey about them: 'People from all over the country and all over the world, with different religious backgrounds, with different cultural backgrounds, different economic status, political beliefs: so many diverse people watch our show, and it's just so wonderful to know that we were able to inspire them in some way.' Sometimes, though, he finds the attention, the lack of respect for his privacy, difficult to deal with. With friends, too, it can be hard. 'It's like the theory of relativity in many ways,' he tells me with a typically scientific flourish, 'because they've changed towards me, they see me change.'

Oka is very conscious of the way people see him, and it's clear that he really isn't a fan of labels. He resisted the uniformity of being stuck in one job, and he's an intriguing mix of Japanese - he greets and bids me farewell with the hint of a bow - and American, his speech sprinkled with California-isms - 'woah' and 'like' and even a 'dude' or two.

But the label that continues to attach itself to him, a hangover from school that has got worse because of the character he plays in Heroes, is 'geek'. He's not annoyed when I bring it up, but perhaps slightly fatigued. 'This has been like my mantra: to be a geek is to be human, because being a geek means that you're passionate about something. And I'd rather be passionate about one thing than be apathetic about everything.'

Perhaps the geek doth protest too much, because part of Oka's appeal is that despite the Grammy and Emmy nominations, there's still a lot of the sweet little guy from the Time cover in him. He's not arrogant, or complacent, and he's sincere when he tells me the most important thing he has in common with Hiro: 'The biggest thing, you know, is that he gets to live his dream of being a superhero, which is something he's dreamt of being all his life, and I get to live the dream of being on a great show, working with so many people and touching so many lives.'