Will Smith was 15 when his first girlfriend cheated on him. He remembers the experience well, the usual broad smile slipping from his cheerful face when he recounts the story. He was still at school and, up until that point, believed wholeheartedly that bad things happen only to bad people.

“That she cheated on me destroyed my concept of cause and effect,” he says, “my belief that good things happen to good people. I thought: ‘That ain’t true.’

“So the process I went through in my 15-year-old brain was that she cheated on me because I wasn’t good enough. I remember lying in bed and making the decision that this would be the last time in my life that I would not be good enough.”

That decision has served him well over the past 24 years. Smith has evolved into the most bankable black actor in the world, eclipsing the likes of Denzel Washington and Samuel L. Jackson and regularly pulling in $20 million (£10 million) paydays to carry home to his second wife, the actress Jada Pinkett Smith.

He is one of the most ebullient actors working today, constantly joshing and joking, the twinkle in his eye as bright as the expensive diamond studs that nestle in his ear-lobes. “I was determined that I would be the best at everything I do,” he continues. “And I remember when I first got to Hollywood saying to my manager: ‘I want to be the biggest movie star in the world’.

“So what we did was to analyse the top ten movies of all time, and we figured out the patterns. We noticed that ten out of ten were special effects movies, and nine out of ten were special-effects movies with creatures, and eight out of ten had creatures and a love story. So when it came to Independence Day, that wasn’t a hard movie to say yes to. And the same with my new movie, I Am Legend. As a concept it is not a hard call to make.” (His next two movies are Hancock, about a flawed superhero, and Empire, directed by Michael Mann.) I Am Legend, a big-budget adaptation of the author John Matheson’s 1950s yarn, is a chilling allegorical tale that blends sci-fi with horror as it projects a postapocalyptic future where a deadly virus has annihilated all but 10 per cent of the Earth’s population. The few survivors have been radically transformed, taking on the form of vampires. One man, however, remains unaltered: Robert Neville, the last man on Earth.

Matheson’s novella has already sired two cinematic incarnations, The Last Man on Earth (1964) with Vincent Price and, seven years later, The Omega Man, starring Charlton Heston. However, this particular version – which casts Neville (Smith) as a military virologist marooned in Manhattan with only an army of cannibalistic creatures for company – is a far slicker interpretation, incorporating different elements from the book and the second of the two films.

“What I loved about the book, the film and our project is that he is the last man on Earth,” Smith says. “That’s like a primordial fear, and it was a frightening prospect. I spoke to POWs and prisoners held in solitary confinement, and they all said you need structure and routine to get through. You also need to keep an internal monologue, otherwise you forget simple things. One man told me that he even forgot what fingers were called.

“So what we have really tried to do is to commit to the small art-house realistic version, staying true to the source material, and yet also have the big blockbuster package.”

Smith’s film achieves that unlikely blend, mixing a bleak human drama with a string of high-octane action sequences. As with his most recent movie, The Pursuit of Happyness (2006) – for which he received the second of his two Oscar nominations – one of his three children stars alongside him. In Happyness it was his four-year-old son Jaden; in I Am Legend it his daughter, seven-year-old Willow. “She won’t accept much direction,” he laughs. “She knows the wardrobe she wants to wear; she knows how she wants to play the scene and she has certainty on how the whole should be delivered. With Willow you allow her to direct you – we had so much fun.”

The artist formerly know as the Fresh Prince has, by all accounts, had fun throughout his career. As the theme rap to his breakthrough TV show, The Fresh Prince of Bel Air, recounts, he’s “West Philadelphia born and raised”, and that “playground where he spent most of his days” was bubbling with kids of all races and creeds.

“I grew up in a working-class environment,” he says. “My mother worked for the school board, my father owned a refrigeration business. My school was 90 per cent white, but 90 per cent of the kids I played with were black. So I got the best of both worlds. I think that is where my comedy developed. In the playground, black kids appreciated comedy about real life. In the white community, fantasy was funnier.”

He took his first steps in the entertainment industry the moment he left that playground, eschewing basketball and a place at the prestigious Massachusetts Institute of Technology – “I was good at maths and science; it was my dream to create the first fully electronic class-room” – to pursue a career in rap.

Along with his friend, the DJ Jazzy Jeff, Smith scooped one of the first Grammy awards given to a hip-hop act, and was a millionaire before he hit 20. “I made a lot of money in the music business,” he says, “and I then lost all that money. Basically, I forgot to pay my taxes, the Government seized everything. I was broke.”

This potentially devastating setback proved temporary, however, and Smith went on to become the most successful crossover music artist ever, cutting his dramatic acting teeth with the bleak melodrama Where the Day Takes You in 1992 and then producing a fine comedic turn in Made in America (1993), before securing the lead role in John Guare’s Oscar-nominated Six Degrees Of Separation in the same year. The mega-budget sci-fi swashbuckler Independence Day (1996) announced Smith’s arrival on Hollywood’s main stage as it scooped more than $800 million at the world-wide box office. He followed that with the two Men In Black movies and a pair of Bad Boys films, and won his first Oscar nomination for Ali in 2001. “That film was amazing for so many reasons,” he says. “Working with [the director] Michael Mann, and of course meeting Muhammad Ali himself. I had first met him years ago, and he was aware that I had turned down the chance to play him then. So when I met him during filming, I didn’t know how he was going to respond.

“I walked up to him and said: ‘Champ, pleasure to meet you’, and Ali said: ‘Man, you’re almost pretty enough to play me!’ We went back and forth for years after deciding who’s the prettier. And of course, learning to fight was amazing. There’s something about being able to fight that goes along with sexual confidence, at least that’s what I found. Confidence is the key to command in your bedroom. Women can smell fear, so there can’t be any in there. That’s my experience.”

Has he encountered racism in Hollywood? “I think the great thing about Hollywood is there’s racism, but on a certain level, everyone’s the same colour – green,” says Smith. “It gets to the point that if you can put butts on seats then people will make films with you.

“I don’t look at myself like I’m making any wonderful social statements, though. If children can be inspired to think that maybe they can do something like I’ve done, then I’ll accept that, but it’s not something that I’m shooting for and consciously trying to do.”

Smith has married twice, first to another actress, Sheree Zampino, whom he met on set of a TV comedy series called A Different World. “Actually, I went to the show to meet [his current wife] Jada. But I met Sheree in the audience and didn’t meet up with Jada – I didn’t meet her until two years later.

“Sheree and I enjoyed ourselves, and we have our son Trey, but relationships are difficult things to manage and we really struggled to manage the difficulty of the lifestyle.

“I was up-and-coming in my career and had to focus on it. That was not the life she imagined she would have – me being away physically and then being away mentally when I was home. It was a little too much pressure for two people that didn’t have certainty in any aspect of their lives. But it’s all amicable, we’re all good.”

Smith married Jada Pinkett in 1997. “Everyday I need my woman to look at me right; I need Jada to have that look in her eyes,” he says. “I can’t function if I don’t see it, whether it’s with my movies, or me as a father, or me as a husband. I have to educate myself to get to the place where I’m the best on Earth.”

He stops, the grin temporarily sliding from his face once more. “Then, and only then, can I be sure that my woman will never leave me.”

I Am Legend is released on Boxing Day

Think big, then bigger: the films of Will Smith

1990 The Fresh Prince of Bel Air
Willard Christopher Smith Jr. made his name as the smooth-talking teenager sent to live with his uncle and aunt in California.

1996 Independence Day
All grown up, Smith lands the part of Captain Steven Smith, heroically battling alien invasion in this Oscar-winning action film.

1997 Men in Black
Still on the alien war path, Smith dons super-smooth sunglasses as a secret agent in this hit sci-fi comedy, and provides the theme song. A sequel followed in 2002.

1999 Wild Wild West
A minor blip – the critics damned this guns-a-blazin’ action comedy as lightweight, predictable and flat.

Smith plays a 19th-century hired gun and again sings the hip-hop theme song.

2001 Ali
Smith soon redeemed himself with an Oscar-nominated performance as boxing legend Muhammed Ali in this intense biopic.

2004 I, Robot
Back to sci-fi, Smith is a techno-phobic detective exploring a murder in a world where humans and robots intermingle.

2006 The Pursuit of Happyness
Starring alongside his real-life son, Smith yanks on the heartstrings as Chris Gardner, a single dad who struggles through destitution to make it as a stockbroker.

Louise Cohen

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