Eugene O'Neill, master of American theatre

In June 1922, F Scott Fitzgerald received a letter from his friend Edmund Wilson, in which he described meeting Eugene O'Neill: "He is an extraordinarily attractive fellow," Wilson wrote. "I find with gratification that he regards Anna Christie as more or less junk and thinks it is a great joke that it won the Pulitzer prize. His genius seems to be only just becoming properly articulate." By 1922, the 34-year-old O'Neill had already won the Pulitzer prize for drama twice and done nothing less than reinvent – or rather invent – legitimate American theatre. But Wilson was, as usual, correct: O'Neill was still finding his voice; his greatest plays, The Iceman Cometh, A Moon for the Misbegotten and the magnificent Long Day's Journey into Night, which many consider the pinnacle of 20th-century American theatre, were yet to come. Audiences will soon have the opportunity to judge Long Day's Journey into Night for themselves, as a revival of O'Neill's masterpiece, starring David Suchet as the father, James Tyrone, opens in the West End next week, exactly 100 years after the play is set.

O'Neill is the only American playwright to have won the Nobel prize for literature, and the only dramatist to have won four Pulitzer prizes. He introduced psychological and social realism to the American stage; he was among the earliest to use American vernacular, and to focus on characters marginalised by society. Before O'Neill, American theatre consisted of melodrama and farce; he was the first US playwright to take drama seriously as an aesthetic and intellectual form. He took it very seriously indeed; one cannot accuse O'Neill of frivolity. Of more than 50 finished plays, O'Neill wrote just one ostensible comedy, Ah, Wilderness! (1933), and even its plot hinges on drunkenness, prostitution, revenge and repressed desire. Of course, most of O'Neill's plays involve drunkenness, prostitution, revenge and repressed desire; Ah, Wilderness! is the only one that manages a happy ending, although A Moon for the Misbegotten (1946) does admit the possibility of forgiveness, a conclusion that for O'Neill seems downright giddy.

His first popular hit was The Emperor Jones in 1920, followed by a string of plays including Anna Christie and Desire Under the Elms in 1924. That same year also saw All God's Chillun Got Wings, a groundbreaking exploration of interracial relations that provoked hate mail and bomb threats. Strange Interlude won a Pulitzer in 1928; three years later O'Neill finished Mourning Becomes Electra. In 1936 he was awarded the Nobel; 10 years later, he produced The Iceman Cometh, followed closely by A Moon for the Misbegotten; both were poorly received. He died in 1953, having requested that Long Day's Journey Into Night be withheld from the stage until 25 years after his death. His widow published it three years later; it was first staged in 1957, and recognised immediately as a triumph, winning O'Neill his final, posthumous Pulitzer and sparking a revival.

His significance can hardly be overstated: without O'Neill, there would have been no Arthur Miller or Tennessee Williams, let alone David Mamet or Sam Shepard. Yet in general his plays are long, arduous, defiantly demanding; O'Neill told a reporter before The Iceman Cometh opened that he'd tried to cut 45 minutes, but had managed only 15: "It will have to run from 8 o'clock to whenever it now goddamned pleases – maybe quarter to 12. If there are repetitions, they'll have to remain in, because I feel they are absolutely necessary to what I am trying to get over."

O'Neill's writing was always driven by an autobiographical impulse; by the time he wrote Long Day's Journey into Night and A Moon for the Misbegotten, he was drawing only the lightest veil between the drama and the dramatist, mining the story of his family's tortured relationships for their universal meanings. The fine line between love and hate is one that O'Neill's characters draw and erase, and draw again: rage explodes, is denied, repressed, avoided and then explodes once more. Addiction is everywhere, accelerating and deepening the suffering it is supposed to be assuaging. Guilt, fury, despair, and the symmetrical need for pity, forgiveness, contrition: these are O'Neill's great themes. When one learns about the extraordinary drama of O'Neill's early years, it is not hard to understand why.

He was born on 17 October 1888, in a hotel in Times Square, New York. His father, James O'Neill, was a famous and popular actor, known for his touring production of The Count of Monte Cristo. Eugene O'Neill's dramas would eventually reject everything his father's career symbolised, the melodramatic tradition of sentimentality and cheap heroics, cardboard characters and overblown rhetoric. It was a tradition he knew well: the young Eugene spent his early years backstage with his mother and older brother Jamie, as they accompanied James around North America. A middle son, Edmund, had died as a baby from measles, which he contracted from six-year-old Jamie; the child was accused of deliberately infecting his brother and remained guilt-stricken for the rest of his sad, foreshortened life.

After giving birth to Eugene, Mary Ellen (known as Ella) O'Neill was prescribed morphine for pain and what we would now call post-natal depression; she rapidly became addicted. When Eugene was 14, his father and brother decided to tell him the truth about his mother's addiction. They seem to have implied that if it weren't for him, none of this misfortune would have befallen the family; Eugene O'Neill's inconsiderate decision to be born had destroyed his mother. Predictably enough, the young O'Neill began to self-destruct, consoling himself with alcohol, narcotics, and prostitutes. Some biographers have asserted that he was an alcoholic by 15; before he was 20, he'd secretly married a girl who was pregnant with his child. Two years later, overcome by shame, he overdosed on Veronal, a popular and easily obtained opiate. A friend got him to the hospital, where his stomach was pumped; the experience became the kernel of his one-act play Exorcism, which was believed to have been destroyed until a copy was found and published last year.

Not long after, O'Neill was diagnosed with tuberculosis and sent to a sanatorium; the experience cemented his decision to dedicate himself to playwriting. He wrote half a dozen apprentice works before Beyond the Horizon established him as a significant voice in American theatre in 1920; his father lived to see his son's success, and was seen wiping away tears of pride at the end of the premiere. In less than a month, however, James O'Neill was hospitalised with cancer and died, painfully, a few months after that. Eighteen months later, O'Neill's mother died suddenly of a brain tumor. Less than two years after that, at the age of 45, Jamie succeeded in his often-stated aim of drinking himself to death; the once close brothers were so estranged that Eugene refused to go to the funeral or help with the burial arrangements. In just over three years, O'Neill had lost his entire family. In some ways, it could be said that he never finished mourning: death, loss and grief are inescapable in his plays; bereavement seems eternal. Throughout this period, unsurprisingly, O'Neill himself was drinking heavily: he would struggle with depression and illness for the rest of his life; when he won the Nobel prize it had to be brought to him in a hospital bed. His final words, reportedly, were: "I knew it. I knew it. Born in a hotel room, and God damn it, died in a hotel room."

O'Neill's plays come to seem a Sisyphean endeavour, struggling up this mountain of grief; there is a real heroism in his obstinate, perpetually uphill battle to come to terms with human suffering. He once said he hoped to "convey the quality of understanding that is born only of pain and rises to perception to reach the truths of human passion. For life to be felt as noble, it must be seen as tragic." His great final play, Long Day's Journey into Night, finally tells the story of the O'Neill family as he had come to understand it. On one painful day in 1912, Edmund Tyrone learns that he has tuberculosis, and his mother, Mary, falls back into her morphine addiction after the latest effort at a cure; her husband and sons battle despair as she flees from her loneliness.

The question of who is to blame drives all four characters into spiralling accusations and defences; eventually they are all to blame, and no one is. A Moon for the Misbegotten is an oblique follow-up, less a sequel than a postscript; it is 11 years later and Jamie Tyrone is about to finish drinking himself to death. Before he does so, he meets a young woman who offers him the forgiveness he has been unable to give himself. The Iceman Cometh, the third play in O'Neill's mighty final triumvirate, is another story of betrayal and remorse, but this time expanding to indict an American society defined by self-delusion and deceit.

Psychological and moral pain creates spiritual and social dilemmas. The more O'Neill's characters yearn for some higher ideal, for spiritual fulfilment or intellectual or moral freedom, the more mired they become in doomed relationships, addiction, and squalour. O'Neill was a finer thinker than has often been acknowledged, and not quite as solipsistic as his plays can seem in isolation. He wrote not only out of his own suffering and damage, but also out of his nation's, rooting his sense of America's modern failures in a framework of classical tragedy. In a famous 1946 interview, O'Neill criticised his complacent nation: "I'm going on the theory that the United States, instead of being the most successful country in the world, is the greatest failure … it was given everything, more than any other country. Through moving as rapidly as it has, it hasn't acquired any real roots. Its main idea is that everlasting game of trying to possess your own soul by the possession of something outside of it, thereby losing your own soul and the thing outside of it, too."

There is little poetry and less subtlety in O'Neill's plays, and no delicacy whatsoever. His ideas were not especially original: he owed as much to Ibsen, Strindberg and Chekhov as to Sophocles and Euripides. It is hard not to share Wilson's sense that O'Neill always struggled to articulate his genius; words constantly fail O'Neill's characters. When Edmund Tyrone tries to tell his father what matters to him in life, he confesses: "I couldn't touch what I tried to tell you just now. I just stammered. That's the best I'll ever do … Well it will be faithful realism, at least. Stammering is the native eloquence of us fog-people." Wilson also said, more damningly, that O'Neill "depends too much upon hatred," but this seems too pat for a writer struggling so hard to transcend his own rage. Kenneth Tynan once observed that Dr Johnson's description of Milton equally applied to O'Neill: "Milton, Madam, was a genius that could cut a Colossus from a rock; but could not carve heads upon cherrystones." O'Neill carved his colossus out of American granite: his greatest plays are hard, obdurate, inescapable, and immense.