Jane Birkin, who helped define chic female sexuality of the 1970s as an actress in arty and erotic European movies and in her relationship — equal parts romantic and artistic — with the singer Serge Gainsbourg, died on Sunday in Paris. Ms. Birkin, who later became known for inspiring one of the best known lines of luxury handbags, was 76.
Her death was confirmed by President Emmanuel Macron of France, who called her “a French icon” in a message on Twitter. The French news media reported that Ms. Birkin had been found dead at her home but that the cause was not immediately known.
The child of a famously beautiful actress and a socially connected British naval officer, Ms. Birkin led a life guided by many happy accidents.
While she was on a flight in 1984, a plastic bag in which she was keeping her possessions broke, leading her to complain aloud that Hermès did not make a bag that could fit all her things. The man sitting next to her happened to be Jean-Louis Dumas, then the head designer of Hermès (and later its chief executive). The company released the Birkin bag line the same year — in just the large size she had requested.
Standard Birkin bags now sell for $10,000, and the difficulties of obtaining one — given a complex manufacturing process and a deliberately rationed supply to boutiques — have given the bag the cachet of exclusivity.
Her relationship with Mr. Gainsbourg began just as fortuitously, in 1968. She was in her early 20s, her first marriage having fallen apart, when, without particular renown as an actress and without speaking a word of French, she managed to be cast in a French movie, “Slogan,” starring Mr. Gainsbourg.
The two fell in love, but Ms. Birkin did not see a way to remain long in France. Then, dining out one night, she had a chance encounter with the French director Jacques Deray, got hired to act in a movie of his, stayed in the country and solidified her relationship with Mr. Gainsbourg.
She lived in France for the rest of her life, and her engagement with Mr. Gainsbourg and his music proved equally enduring.
The most notable product of their collaboration and romance was their 1969 hit recording of Mr. Gainsbourg’s song “Je t’aime… moi non plus” (“I Love You… Me Neither”).
In the song, a duet, Mr. Gainsbourg speaks of sex in a low, conversational voice as Ms. Birkin confesses her love in suggestive murmurs and moans and the high-pitched singing of an ingénue.
The song was condemned by the Vatican and banned in several countries and by the B.B.C. television network. But it sold millions of copies.
Nearly 50 years later, in 2018, Ms. Birkin was still singing music by Mr. Gainsbourg, by then on a world tour of orchestral versions of his songs.
“If I am singing in Argentina in two weeks’ time,” she told The Guardian, “it is because of ‘Je t’aime.’”
Jane Mallory Birkin was born in London on Dec. 14, 1946, to Judy Campbell, an actress who gained renown for performing for British troops with Noël Coward during World War II, and Cmdr. David Birkin of the Royal Navy.
In 2021, her father’s exploits during World War II were recounted in “A Dangerous Enterprise,” a book by Tim Spicer, a former British military officer. Commander Birkin’s duties included navigating boats on moonless nights across the English Channel to bring to safety Allied spies, stranded airmen and escaped prisoners of war who had found themselves in France.
Ms. Birkin, at 18, married the British composer John Barry, known for arranging the trademark theme to James Bond movies, and they had a daughter, Kate. At 20, Ms. Birkin appeared in Michelangelo Antonioni’s hit 1966 movie, “Blow Up,” an erotic tale of a London fashion photographer. She played a fashion model — the credits listed her as only The Blonde — and gained some attention for a risqué nude scene.
“Had it all worked out with John Barry, I would never have been curious to know what was going on anywhere else,” Ms. Birkin told The Guardian in 2017. “I would have just gone on being his wife. I would have been delighted. But because he went off with someone else, and I was left with Kate, I had to find a job quite fast.”
That led to her audition for “Slogan.”
The movie that kept her in France was “La Piscine” (“The Swimming Pool”), starring Alain Delon and Romy Schneider. (It found unexpected renewed popularity in the United States in 2021.) A sun-soaked film of sex and jealousy with many shots of scantily clad actors, the movie proved to be an effective showcase for Ms. Birkin’s long-limbed beauty.
Her romance with Mr. Gainsbourg captivated the French public. She was the young doe-eyed expat, he the aging but still virile artistic genius. The relationship lasted for more than a decade, ending when she left him in the early 1980s for the French film director Jacques Doillon. Mr. Gainsbourg died in 1991 at 62.
Though Ms. Birkin would later speak self-deprecatingly about her role as Mr. Gainsbourg’s muse, she embraced becoming “the keeper of the Gainsbourg flame,” as The New York Times labeled her in 2018.
She described to The Times connections between the music he wrote for her and work by classical composers like Chopin and Brahms.
“I would have thought that he was probably France’s most modern writer,” she said. “He invented a new language, he cut words in two like Cole Porter.”
Ms. Birkin released “Oh! Pardon tu dormais…,” her first album of her own songs written in English, in 2021. “The results are an emotional tour de force from an artist who has never gotten her musical due outside of France,” the music writer Ben Cardew wrote in a review for Pitchfork.
Ms. Birkin also continued to act, including in films by Agnès Varda and plays by Patrice Chéreau. She was also popular in France as an activist for women’s and L.G.B.T.Q. rights as well as for her British accent when speaking French, which the French found endearing.
“The most Parisian of the English has left us,” the mayor of Paris, Anne Hidalgo, wrote in a message on Twitter on Sunday. “We will never forget her songs, her laughs and her incomparable accent.”
Ms. Birkin had a mild stroke in 2021 and had recently canceled a series of concerts because of health issues.
She is survived by two daughters, one with Mr. Gainsbourg and the other with Mr. Doillon: the singer-actresses Charlotte Gainsbourg and Lou Doillon, each of whom has, like their mother, inspired designers and followers of fashion. Her other daughter, Kate Barry, a photographer, died at 46 in 2013 in a fall from a window of her fourth-floor Paris apartment.
Ms. Birkin discovered that her romantic separation from Mr. Gainsbourg did not dim their collaboration. He kept writing new songs intended for her until he died.
After their breakup, “you could talk back to him for once,” she told The Guardian. “You were not just his creation any more.”
Guy Trebay contributed reporting from New York.