WHO WAS HITLER? The question may seem ludicrous, given the vast outpouring of books, television programmes and films about the man. Amazon offers no fewer than 32,000 books about the Nazi dictator; only Jesus has more literature devoted to him, while Stalin merits half as much. We have learnt, variously, that Hitler was a vegetarian teetotaller, a racist demagogue, an opera nut, a drug addict, a bore, and possibly homosexual. And yet this most massive of 20th-century figures has always seemed to me strangely cardboard: a manic, air-pawing ranter in flickering black-and-white propaganda movies, a one-dimensional monster and, finally, a caricature, a goose-stepping Basil Fawlty, the Fuhrer as freak, an abomination with a funny moustache. Whatever else he was, Hitler wasn't quite real, or human.

That is how most popular culture has chosen to represent Hitler in the postwar years, as an extraordinary, unrepeatable symbol of the purest wickedness.

Sixty years after Hitler's death, that comforting approach has now been directly challenged by a new German film that portrays the Nazi dictator, for the first time, as a realistic human being, an undertaking as daring as it is dangerous. Der Untergang (The Downfall) chronicles Hitler's last 12 days in the bunker, based on witness accounts and diaries. Played by the Swiss actor Bruno Ganz, the 56-year-old dictator trembles from Parkinson's disease and hides his shaking hands behind his back out of tattered pride. The bitter tirades as his army disintegrates before the Soviet advance are interspersed with moments that veer close to sympathy: he weeps; he is gentle and charming towards his female staff; and tender to Eva Braun, marrying her the day before their suicide.

Alec Guinness portrayed the same historical moment in the 1972 film The Last Ten Days, as did Anthony Hopkins in The Bunker in 1981, but both films were careful to stick closely to the Hitler-as-monster formula: the Hopkins character was not far off being Hannibal Lecter in a Nazi uniform. Der Untergang, by contrast, has broken new ground by depicting Hitler as a complex individual, by giving, in the words of Der Spiegel,"a real face to the absurd drama in the concrete ghetto".

Inevitably, the new film has prompted fury among those who believe that attributing human characteristics to the architect of the Holocaust desecrates the memory of his millions of victims. Enraged that Hitler could be depicted eating chocolate cake and being kind to his pet dog Blondi, The Daily Mail demanded to know:"Is Germany finally forgiving Hitler?" The reverse is surely the case, for by moving beyond the cartoon image of a deranged villain, Germany may finally be condemning Hitler for what he was: a human capable of grossly inhuman acts. Trying to understand Hitler is not the same as explaining him, let alone excusing him.

A Hitler who is simply a mad aberration was easier for Germans to live with; as the historian John Lukacs has observed:"The simplistic affixing of the abnormal label to Hitler relieves him, again, of responsibility". But a Hitler who was, in some ways, quite normal, even sympathetic, is more truly disturbing than the overdrawn image of a mass-murdering demagogue. The enduring fascination of Nazism for some people lies in the grandiosity of its perverted vision; puncture that grandiosity, by making its progenitor believably human, and the macabre allure begins to ebb.