Anita Pallenberg, left, with Rolling Stones guitarist Keith Richards at the premiere of the 1970 film “Performance,” in which she starred. (Keystone/Getty Images)

Anita Pallenberg, a model and actress who was sometimes called the muse of the Rolling Stones and had affairs with three of the band’s key members, including a decade-long, drug-fueled relationship with Keith Richards, died June 13 at a hospital in Chichester, England. She was 75.

Richards confirmed her death to the Associated Press through a spokesman. The cause was not known, although she reportedly had hepatitis and other ailments.

The alluring Ms. Pallenberg, who met the Stones by sneaking backstage at a concert in 1965 and offering the band hashish, may have been the ultimate ’60s rock-and-roll “it girl.” She quickly became the lover of one of the band’s guitarists, Brian Jones, then left him for Richards, with whom she had three children and a shared appetite for heroin.

While making the cult classic film “Performance” with Mick Jagger in 1968, she reportedly had an affair with the Stones’ lead singer. The strikingly beautiful Ms. Pallenberg had such a magnetic presence — an “evil glamour,” in the words of Jagger’s onetime paramour, Marianne Faithfull — that she was credited with helping mold the group’s lasting image.

“She almost single-handedly engineered a cultural revolution in London,” Faithfull wrote, “by bringing together the Stones and the jeunesse dorée” — the young, fashionable and rich. “The Stones came away with a patina of aristocratic decadence that . . . transformed the Stones from pop stars into cultural icons.”

Anita Pallenberg and Keith Richards with their newborn son, Marlon, in 1969. (John Minihan/Getty Images)

Throughout the 1960s, Ms. Pallenberg seemed to be everywhere. She grew up in Rome and was an international model who spoke several languages; she was part of Andy Warhol’s eclectic group of artists at the Factory in New York, where she became friendly with Beat Generation writers Allen Ginsberg and William Burroughs; she acted in films alongside Jane Fonda and Marlon Brando.

Faithfull described her as “dazzling, beautiful, hypnotic and unsettling. . . . Other women evaporated next to her.”

When Ms. Pallenberg entered the orbit of the Rolling Stones, they were seen as the raw, street-savvy counterparts to the Beatles. She was originally linked with Jones, and they soon adopted identical haircuts.

But their relationship took a violent turn, and during a trip to Spain and Morocco in 1967, Richards saw that Jones was beating Ms. Pallenberg. Richards took her back to England, leaving Jones stranded in North Africa.

“It’s said that I stole her,” Richards wrote in “Life,” his 2010 autobiography. “But my take on it is that I rescued her.”

By the time Jones drowned in his swimming pool at age 27 in 1969, Ms. Pallenberg was pregnant with her first child with Richards. They named their son Marlon after Brando, with whom Ms. Pallenberg appeared in a campy 1968 sex farce, “Candy.”

She had a role in the 1968 science fiction spoof Barbarbella, opposite Fonda, then co-wrote and acted in the surreal “Performance,” which was set in the London underworld and starred ­Jagger in an androgynous role. The sex scenes between Ms. Pallenberg and Jagger were so steamy that they won an award at a Dutch film festival — a porn film festival.

Anita Pallenberg in 1968. (Larry Ellis/Express/Getty Images)

Richards later wrote that on the day he realized Jagger and Ms. Pallenberg were having an affair, he composed the opening lyrics to one of the Stones’ greatest songs, “Gimme Shelter,” accompanied by a snarling guitar riff:

Oh, a storm is threat’ning

My very life today

If I don’t get some shelter

Oh yeah, I’m gonna fade away

Ms. Pallenberg was a constant presence with the Stones in the late 1960s and 1970s, when they recorded several of their most acclaimed albums, including “Let It Bleed,” “Sticky Fingers,” “Exile on Main St.” and “Goats Head Soup.”

For a while, Ms. Pallenberg matched the highflying, dope-taking, deal-with-the-devil way of life of Richards. Her fashion sense influenced the Stones’ flamboyant style, and Richards, who was the same size as the 5-foot-9 Ms. Pallenberg, sometimes wore her gender-bending outfits onstage.

The couple had a daughter, Dandelion, in 1971. Another son was born five years later, but he died at the age of 10 weeks of sudden infant death syndrome.

Richards and Ms. Pallenberg never married, but their 12-year relationship was marked by heroin addiction, drug arrests, tempestuousness and tears. Richards’s mother decided Ms. Pallenberg was an unfit parent and raised their daughter, who dropped the name Dandelion in favor of Angela.

Both Richards and Ms. Pallenberg were known to stray, and in 1979 a 17-year-old boy killed himself in Ms. Pallenberg’s company, possibly while playing Russian roulette. She was cleared of any culpability in his death.

Richards broke up with her soon afterward, and Ms. Pallenberg fell into a deeper spiral of drug and alcohol addiction. She entered rehabilitation in 1987. Except for an unshakable cigarette habit, she said she was largely drug-free in her later years.

“I like a high-spirited woman,” Richards wrote in his autobiography. “And with Anita, you knew you were taking on a Valkyrie — she who decides who dies in battle.”

Anita Pallenberg was born April 6, 1942, in Rome. (Her year of birth is listed in most records as 1944, but Richards’s spokesman confirmed the earlier date.) Her father was a travel agent.

She was expelled from a German boarding school when she was 16 and became a model in Italy and New York.

In 1994, Ms. Pallenberg received a degree in fashion from Central Saint Martins, a London art school, and became an influence on model Kate Moss and fashion designers Bella Freud and Stella McCartney.

After having two hip replacements, she resumed acting in her 60s, appearing in Abel Ferrara’s “Go Go Tales” (2007), and Harmony Korine’s “Mister Lonely” (2007).

She was often asked about writing her memoirs, but never did. “I had several publishers and they were all the same,” she told the Guardian in 2008. “They all wanted salacious.”

Survivors include her children and five grandchildren.

Richards has been married to onetime model Patti Hansen since 1983. Ms. Pallenberg never married.

“She knew everything and she could say it in five languages,” Richards once said about her. “She scared the pants off me.”

In a 2008 interview with the Guardian, she said, “I still do.”