Hefner is survived by his third wife, Crystal Harris
Hugh Hefner, founder of the international adult magazine Playboy, has died at the age of 91.
Playboy Enterprises Inc said he passed away peacefully at home, from natural causes.
Hefner began publishing Playboy in his kitchen at home in 1953. It became the largest-selling men's magazine in the world, shifting seven million copies a month at its peak.
Cooper Hefner, his son, said he would be "greatly missed by many".
He paid tribute to his father's "exceptional and impactful life as a media and cultural pioneer," and called him an advocate for free speech, civil rights and sexual freedom.
Hefner's trailblazing magazine helped make nudity respectable in mainstream publications, despite emerging at a time when US states could legally ban contraceptives.
It also made him a multi-millionaire, spawning a business empire that included casinos and nightclubs.
The first edition featured a set of nude photographs of Marilyn Monroe that Hefner had bought for $200. They had originally been shot for a 1949 calendar.
The silk pyjama-clad mogul became famous for his hedonism, dating and marrying Playboy models. In his later years he threw decadent parties at his luxurious mansions in Chicago and Los Angeles.
He claimed to have slept with more than 1,000 women, and credited the impotence drug Viagra with maintaining his libido.
Playboy "bunnies" model the brand's world-famous silhouette
From 2005-10, a reality TV show called "The Girls Next Door" showcased Hefner's libertine lifestyle - and the harem of young blonde women who shared it.
In 2012, aged 86, he married his third wife Crystal Harris - who was 60 years his junior.
Though critics saw Playboy as a byword for sleaze, its founder - who was born into a strict Methodist family - never shared that view.
"I've never thought of Playboy quite frankly as a sex magazine," Hefner told CNN in 2002. "I always thought of it as a lifestyle magazine in which sex was one important ingredient."
Hefner faced obscenity charges in 1963 for publishing and distributing Playboy, but the jury was unable to reach a verdict.
The magazine's most significant interviewees included civil rights leader Martin Luther King Jr, Beatle John Lennon, and Cuban revolutionary Fidel Castro.
Its huge sales were certainly driven by glossy colour pictures of nude "playmates", but it also developed a reputation for fine writing, with Norman Mailer, Kingsley Amis, Kurt Vonnegut, James Baldwin, Vladimir Nabokov, Margaret Atwood and Ray Bradbury among its contributors.
Their contributions allowed men to say they did not buy the magazine only for the pictures.
US President Donald Trump appeared on the cover in March 1990, with the tag-line: "Nice magazine, want to sell it?"
The notorious Playboy mansion in Beverly Hills
Hefner and his playmates travelled on Playboy's "Big Bunny" jet during the magazine's 1970s heyday
In the 1980s, competition from publications carrying more explicit photos saw Playboy's circulation decline, and Hefner himself suffered a stroke in 1985.
His daughter Christie took over Playboy Enterprises four years later, and Hefner retreated to his mansion, living with a bevy of women. Cooper Hefner took on a major role in the company in 2014 after Christie stepped down in 2009.
The magazine decided to scrap nudity in March 2016, but reversed its decision earlier this year.
A neighbour of Hefner's in August last year bought the Playboy mansion for $100m, but agreed Hefner could continue to live there until he died.
This file photo taken on August 21, 1970 shows US Playboy Magazine publisher Hugh Hefner giving a press conference at Le Bourget airport in France. Image copyright - AFP/GETTY IMAGES
-- Courtesy of BBC News