Pekar was found dead early Monday by his wife, writer Joyce Brabner, at home in Cleveland Heights, Ohio, said Powell Caesar, a spokesman for the Cuyahoga County coroner's office. An autopsy will be conducted to determine cause of death.
Many of Pekar's writings benefited immeasurably from the quality of the accompanying artwork, supplied by such collaborators as Frank Stack and R. Crumb, a longtime friend and early supporter of Pekar. Crumb once praised Pekar's gift for spinning art out of one man's middle American reality "so staggeringly mundane it verges on the exotic."
Pekar's most famous non-serialized work, "The Quitter" (2005), a book-length, backward-glancing appraisal of his scrappy younger days and the formation of certain of his lifelong obsessions and neuroses, was illustrated by Dean Haspiel. Pekar and Brabner collaborated on "Our Cancer Year," an unsparing account of the author's battle with lymphoma, illustrated by Stack.
Although Pekar's work and public utterances expressed a deep skepticism toward power, privilege and intellectual conformity (and those who wield them as tools against the masses), he evinced generosity and empathy toward ordinary Americans, especially fellow loners and outsiders.
Besides his own autobiographical writings, Pekar chronicled others' lives in such works as "American Splendor: Unsung Hero" (2003), which examined the Vietnam War experience of one of his co-workers at a Cleveland veterans hospital.
Rather than merely depressive whingeing, Pekar's work was capable of radiating an anguished spiritual yearning that fans found to be as ennobling as it was mordantly funny and that some critics regarded as downright Dostoevski-esque in its agonized humanity.
Pekar's artistic and political sensibilities were shaped by the 1960s counterculture. Besides his notable role in championing the novelistic graphic comic book, he had an intense dedication to jazz and to avant-garde and underground art forms in general.
His dust-ups with David Letterman during appearances on the late-night talk show endure today on You Tube as minor classics of pugilistic repartee. In those encounters, Pekar upbraided General Electric, the corporate parent of Letterman's NBC network, and made his host's famous grin dissolve into a grimace after calling him "a shill for GE." For a time, Pekar was banned from the program.
In an interview Monday, comic book writer and historian Mark Evanier said that readers of Pekar's work "knew the details of his life better than they knew the lives of some of the great star superheroes."
Evanier once met Pekar at a comic book convention in Chicago, "and it was not a pleasant encounter."
"He was just running around complaining that he had to give this talk that he had agreed to and there were no doughnuts," said Evanier. "It was oddly reassuring that in real life, he was the exact same person that he was in the comic books or sitting kvetching with David Letterman."
Born Oct. 8, 1939, Pekar was the child of Polish Jewish immigrants. He, his parents and his younger brother lived above the family's grocery store.
Pekar dropped out of Case Western Reserve University and eventually found a job as a file clerk with the Cleveland Veterans Administration Hospital. After retiring from that job in 2001, he continued to write and collaborate on books about the Beat Generation, the 1960s activist group Students for a Democratic Society and Macedonia's efforts not to get drawn into the Balkans conflict of the late 1990s, as well as jazz criticism.
He won the American Book Award in 1987 for his first compilation of "American Splendor." The 2003 film dramatization of his work, also called "American Splendor," took home the Sundance Film Festival's Grand Jury Prize for drama.
In a statement, actor Paul Giamatti, who portrayed Pekar in the film, called him "one of the most compassionate and empathetic human beings I've ever met."
"He had a huge brain and an even bigger soul," Giamatti said. "And he was hilarious. He was a great artist, a true American poet, and there is no one to replace him."
Pekar also wrote the libretto for musician-composer Dan Plonsey's "jazz opera," a meta-autobiographical work suitably titled "Leave Me Alone," in which the two men played themselves.
At home in metropolitan Cleveland, Pekar took pleasure in cultivating what he described as a simple, writing-focused, gastronomically incorrect lifestyle (potato chips, frozen foods). He reportedly wrote every day, using a two-finger typing style.
Brabner was his third wife. He immortalized their romance in an issue of "American Splendor," bearing the subtitle "Harvey's Latest Crapshoot: His Third Marriage to a Sweetie from Delaware and How His Substandard Dishwashing Strains Their Relationship."
In addition to Brabner, Pekar is survived by the couple's daughter, Danielle.
Times staff writers Dennis McLellan and Valerie Nelson contributed to this report.