The newspaper on Wednesday said Flynt's brother Jimmy Flynt confirmed his death but did not cite a specific cause.

Flynt suffered from a variety of health problems since a 1978 assassination attempt that left him a paraplegic.

Flynt loved to aggravate his critics with stunts such as wearing a nappy made from an American flag to court and was involved in a number of legal battles.

In the most famous, the US Supreme Court made an important First Amendment ruling in favour of Flynt in a libel battle with evangelist Jerry Falwell.

Flynt had published a fake ad in Hustler that depicted Falwell saying his first sexual encounter had been with his mother in an outhouse. Falwell sued for $US50 million and won a lower court ruling but in 1988 the Supreme Court said the ad was a parody and protected by free speech standards.

In his heyday, Flynt lived a life that could have made Caligula blush. He wrote in his autobiography that his first sexual experience was with a chicken and told of having sex every four or five hours during a workday. After he was paralysed, Flynt had penile implant surgery so he could continue to have sex.

Flynt created a business with an estimated turnover of $US150 million at one point. As magazine circulation slipped, he invested in adult-oriented television channels, a casino, film distribution and merchandise.

He said he never objected to being labelled a smut peddler as long as he was considered a First Amendment crusader, too.

"Just because I publish pornography does not mean that I am not concerned about the social ills that all of us are," he told an interviewer.

Flynt was often in legal trouble, fighting obscenity charges or lawsuits, and he often turned courtroom appearances into spectacles. His outbursts once prompted his own lawyer to ask a judge to have Flynt bound and gagged.

Born in 1942, Flynt grew up in poverty in Kentucky and Indiana and dropped out of school after the eighth grade. After stints in the armed forces and a General Motors plant, he and his brother opened the Hustler Club in Dayton, Ohio, in 1968. By 1973 it had grown to a string of strip clubs and Flynt put out a newsletter to promote them.

That newsletter evolved into Hustler magazine, which came to be infamous for featuring explicit photos that made competitor Playboy seem mild. Flynt made a point of publishing photos of women's genitalia.

At its peak, Hustler reportedly had a circulation of three million. Larry Flynt Publications also put out other porn magazines, as well as movies and mainstream magazines.

Flynt revelled in controversy. He made news by publishing pictures of a nude Jacqueline Kennedy Onassis sunbathing in 1975 and a cover photo of a naked woman being fed head first into a meat grinder.

"My competitors always masqueraded their pornography as art," Flynt told the Cincinnati Post. "We never had any pretensions about what we did ... We have proved that barnyard humour has a market appeal."

In 1977 he was convicted in Cincinnati of pandering obscenity and participating in organised crime but the verdict was overturned.

In 1978 Flynt was on trial on similar charges in Lawrenceville, Georgia, when he and his lawyer were shot. Joseph Paul Franklin, a white supremacist, later confessed to the shootings, saying he was upset by Hustler's photographs of interracial sex, but was never prosecuted.

Flynt was left paralysed from the waist down and restricted to a gold-plated wheelchair for the rest of his life.

In October 2013, one month before Franklin was executed in Missouri for racially motivated murders not related to the Flynt shooting, Flynt wrote in the Hollywood Reporter he did not believe in the death penalty.

He did want vengeance, however: "I would love an hour in a room with him and a pair of wire-cutters and pliers so I could inflict the same damage on him that he inflicted on me."

His life was depicted in the 1996 movie The People vs Larry Flynt, which starred Woody Harrelson and was based in part on Flynt's Supreme Court case.

Flynt, a Democrat, ran for president against Ronald Reagan - promoting himself as "the smut peddler who cares" - and in 2003 campaigned for governor of California.

In 1977, he converted to evangelical Christianity at the urging of Ruth Carter Stapleton, sister of President Jimmy Carter, but renounced those beliefs following the Georgia shooting.

He was married five times and had four surviving children.

Australian Associated Press