The original Italian stallion

Marcello Mastroianni was so laid back that he didn't get round to fame until middle age. Robin Buss on the epitome of the Italian male

If there were a single word to describe the screen image of Marcello Mastroianni, it would be "suave". He came late to cinema, having spent the war years in hiding from the Germans and his early twenties acting with Luchino Visconti's theatre company. When he got his first serious cinema roles, in films like Alessandro Blasetti's It's Too Bad She's Bad and Carlo Lizzani's Chronicle of Poor Lovers, it was 1954 and he was already 30, too old for boyish innocence or first love. A long apprenticeship in comedy all'italiana added a hint of ironic detachment and by the time he won international fame as the star of La Dolce Vita, it was as an ageing roué, well battered by life. There was nowhere for a handsome guy to go but suave.

If there were a single word to describe the screen image of Marcello Mastroianni, it would be "suave". He came late to cinema, having spent the war years in hiding from the Germans and his early twenties acting with Luchino Visconti's theatre company. When he got his first serious cinema roles, in films like Alessandro Blasetti's It's Too Bad She's Bad and Carlo Lizzani's Chronicle of Poor Lovers, it was 1954 and he was already 30, too old for boyish innocence or first love. A long apprenticeship in comedy all'italiana added a hint of ironic detachment and by the time he won international fame as the star of La Dolce Vita, it was as an ageing roué, well battered by life. There was nowhere for a handsome guy to go but suave.

It sounds like a limitation, but most of the time it wasn't. Mastroianni clearly took his acting seriously, but he was never solemn about it. He had method, but found the histrionics of The Method merely amusing; he never tried to hog the camera or upstage his co-stars. And, bad though some of his films were, he seldom made you feel embarrassed for him. He had a reputation for laziness that was quite easy to believe: the suavity of his screen persona could be cool to the point of immobility - in Nikita Mikhalkov's Chekhovian Black Eyes, for example, he never convinces you that real passion has roused him from his disenchantment with life.

But his filmography was huge - he never stopped working, right up to Three Lives and Only One Death, released in 1996, the year he died. This was a film for the Chilean director Raoul Ruiz and Mastroianni played four parts. Much of his output was never seen here, so there were sides to his acting that were under-appreciated. This month, at the National Film theatre, a judicious selection of 24 films by Geoffrey Nowell-Smith gives an opportunity to fill in a few gaps.

The biggest gap is comedy. Mastroianni and Sophia Loren made up one of the most effective comic partnerships in cinema history, starting in 1954 with Blasetti's Too Bad She's Bad, but only reaching an international audience 10 years later, in Vittorio De Sica's Marriage Italian Style. A certain degree of restraint was the essence of comedy "Italian-style", which depended less on clowning than on the gradual build up of situation and character. Unfortunately, the NFT season doesn't include one of the best comedies of this type, I Soliti Ignoti, probably because Mastroianni only had a supporting role; but Il bell'Antonio, Divorce Italian Style and others give a taste of the genre and the actor's talent for it.

Mastroianni's most famous partnership, however, was with Federico Fellini, who after La Dolce Vita seems to have come to think of the actor as an alter ego - most obviously in 81/2, where he cast Mastroianni as a film director trying to overcome a creative block on the subject of his next film. They say that when Fellini was filming, he and Mastroianni would walk around the set at Cinecittà between shots with their arms around each other's shoulder, Fellini listening to Mastroianni's accounts of his most recent amorous adventures - an almost too perfect image of the actor as actor and the director as voyeur.

Apart from Fellini, he worked for some of the great Italian film-makers of his time. It was Visconti who gave him his first breaks, in the theatre, then in an adaptation of Dostoyevsky's White Nights. He starred opposite Jeanne Moreau and Monica Vitti in Antonioni's La Notte, and for the Taviani Brothers in Allonsanfan. He did not often go abroad to make films, except to France, where he had an affair and a child with Catherine Deneuve. For his first films in English he had to learn the lines phonetically. One feels that at times he was happy to drift along, taking good parts and bad, and probably living a full life off the screen.

At his best, though, he was very good. But perhaps that is not the point. Somehow, because of a combination of intelligence, good looks and acting ability, he managed to become the epitome of the mature, charming, essentially unreliable Italian male. And, while Italian cinema rose from the solid commercialism of the 1950s to the magnificent individualism of the 1960s, then plunged into the doldrums of the 1980s and beyond, Mastroianni was there, in good films and bad, doing what he was required to do with consummate authority and grace.

The Marcello Mastroianni season runs from 3 August, when Anna Maria Tatò will be in NFT1 to introduce a screening of her film biography of the actor, and runs throughout the month; NFT, SE1, 020 7928 3232