Welles causes endless trouble because of his unstable place in the American cultural hierarchy of high and low. Photograph by Skrebneski

The most popular Orson Welles video on YouTube, edging out the trailer for “Citizen Kane” and “The War of the Worlds” broadcast of 1938, is called “Orson Welles Drunk Outtake.” It shows him slurring his way through one of those ads in which he intoned, “Paul Masson will sell no wine before its time.” Whether he was drunk, experiencing the effects of medication (he suffered from diabetes and other ailments), or simply very tired is immaterial. What’s striking about the video is its popularity. This is largely how today’s culture has chosen to remember Welles: as a pompous wreck, a man who peaked early and then devolved into hackwork and bloated fiascos.

The video points to a decades-old fissure in the reputation of Welles, whose centennial fell on May 6th. The film critic Jonathan Rosenbaum, the author of the 2007 book “Discovering Orson Welles,” observes that commentary tends to fall into “partisan” and “adversarial” categories—adversarial meaning a tendency to celebrate the early work while detecting portents of disaster. Pauline Kael’s long essay “Raising Kane,” which appeared in this magazine, in 1971, propagated that view: she praised “Kane” effusively but attributed many of its best features to the screenwriter Herman Mankiewicz and other collaborators. After that film, Kael wrote, Welles “flew apart, became disorderly.” A 1985 biography by Charles Higham condensed the standard story into its subtitle: “Orson Welles: The Rise and Fall of an American Genius.”

The partisans, bemoaning the fixation on “Kane,” highlight later entries in the canon. Following Welles’s own preference, they often name the 1965 Falstaff film, “Chimes at Midnight,” as his greatest achievement. Like so many obsessives, they acknowledge one another with secret handshakes, making reference to obscure or nonexistent works: the radio show “His Honor the Mayor,” the TV pilot “The Fountain of Youth,” the work print of the unfinished nineteen-seventies film “The Other Side of the Wind,” the lost ending of “The Magnificent Ambersons.” A raft of new books in the centennial year, together with publications from the past decade, suggests that the partisans are slowly gaining ground.

Enthusiasts and skeptics agree that Welles has a way of slipping from one’s grasp. On one hand, he spun tales of damaged power: a newspaper tycoon rises from poverty and ends in desolation; a cop fakes evidence in order to convict people he thinks to be guilty; a macho director secretly longs for the young male stars of his pictures. Truffaut once described Welles’s work as a meditation on the “weakness of the strong.” On the other hand, the movies take life from the margins, from the grotesques in the background. “Touch of Evil” becomes sublime at the moment when Marlene Dietrich saunters into view, as the proprietor of a Mexican brothel that echoes with skeletal player-piano music. The films are full of plays within plays, screens upon screens; an incessant flicker of shadows on walls reminds us that we are looking at projected images. All this comes to a head in the late-period masterpiece “F for Fake,” a study of hoaxes that itself turns out to be a hoax.

Welles causes endless trouble because of his unstable place in the American cultural hierarchy of high and low. He loved tragedy and vaudeville, Expressionist cinema and boys’ adventure stories. He converted genre vehicles like “Touch of Evil” into surreal labyrinths; he made “Macbeth” look like Gothic horror. He was a subversive populist, a celebrity avant-gardist. He was also, frequently, a political artist, one who came of age during the heyday of the Popular Front and never ceased to roil the culture industry. Despite acres of commentary, much about him remains relatively unexplored: his identification with African-Americans, his investigation of sexual ambiguities. In a strange way, he is still active, still working; if, as is hoped, a completed version of “The Other Side of the Wind” soon emerges, he may confound us once again.

The familiar part of the Welles saga, his rapid rise to the pinnacle of “Kane,” has been told many times, most stylishly in Simon Callow’s 1995 book, “Orson Welles: The Road to Xanadu”—the first of three biographical volumes to date, with a fourth to follow. But Patrick McGilligan’s “Young Orson: The Years of Luck and Genius on the Path to ‘Citizen Kane’ ” (HarperCollins), the product of years of meticulous research, may be the definitive account. It reveals, among other things, that Welles’s reputation as a self-mythologizer is itself a bit of a myth: quite a few improbable anecdotes turn out to be more or less true. Did Welles see Sarah Bernhardt perform in Chicago? Did he make his stage début as Sorrow, the child in “Madama Butterfly,” at the Ravinia Festival? Absolute confirmation is lacking, but the chronologies line up. (A detail from the Chicago Tribune: at a 1919 performance of “Butterfly,” an unnamed child of unusual heft substituted as Sorrow, causing giggles in the audience.)

Welles was born in Kenosha, Wisconsin. His father, Richard, was a charming, dissipated inventor who worked for a manufacturer of bicycle lamps; his mother, Beatrice Ives Welles, was a pianist and an activist. Welles’s worldliness evidently stemmed from his father, his artistic gifts and radical tendencies from his mother. McGilligan, who has written biographies of Alfred Hitchcock, Fritz Lang, and Nicholas Ray, has combed through newspaper archives and unearthed many new details of Beatrice’s activities, which included suffragist campaigns and a stint on the Kenosha school board. Beatrice died in 1924, of hepatitis, just after Orson’s ninth birthday. Richard lived for six more years, his health ruined by alcoholism. Maurice Bernstein, a social-climbing Chicago doctor who had befriended the couple, became Orson’s guardian, shuttling him around while engaging in a flurry of high-profile affairs.

Welles attended the Todd School for Boys, in Woodstock, Illinois, and the school’s headmaster, Roger Hill, became a father figure to him. In school plays, Welles directed, designed sets, made costumes, and acted a slew of roles, including Christ, Judas, and the Virgin Mary. Shortly after graduating from Todd, at the age of sixteen, Welles persuaded Bernstein to let him travel alone to Ireland, and soon made his professional acting début at the Gate Theatre, in Dublin. His success was reported in the New York Times, which called him “amazingly fine.” By 1934, when he was nineteen, he had made his Broadway début, as Tybalt in “Romeo and Juliet.” He had also married the actress Virginia Nicolson—the first of three less than happy marriages, yielding three not always happy daughters. His oldest child, Chris Welles Feder, records his inadequacies as a father in her affecting, forgiving 2009 memoir, “In My Father’s Shadow.”

Welles’s almost overnight emergence as the boy genius of the American theatre is often attributed to luck. He himself said so, and “luck” appears in McGilligan’s subtitle. But the decisive factor was the cultural-political atmosphere of the mid-thirties. For the only time in American history, the government was generously funding the arts, by way of the Works Progress Administration, and radio networks and movie studios were cultivating “quality” or “prestige” projects. During this period, Toscanini became a star of NBC radio and several Thomas Mann novels became Book-of-the-Month Club selections. Neither Callow nor McGilligan does full justice to the New Deal underpinnings of Welles’s career; for that, you have to turn to Michael Denning’s 1996 book, “The Cultural Front,” which presents Welles as the “American Brecht,” or to James Naremore’s classic study “The Magic World of Orson Welles,” recently reissued by the University of Illinois.