Hubert de Givenchy, a French designer whose fashions influenced haute couture in the 1950s and ’60s and transformed his close friend, actress Audrey Hepburn, into a style legend, died Saturday at 91.

For more than four decades, he bridged the U.S. and Parisian fashion worlds, designing effortlessly chic clothes that adorned European royalty and Hollywood stars. He clothed Greta Garbo, Marlene Dietrich, Grace Kelly, Lauren Bacall, Elizabeth Taylor and some of the world’s most fashionable women, including First Lady Jacqueline Kennedy and socialites Rachel “Bunny” Mellon and Catherine “Deeda” Blair.

“Givenchy has long been a classicist, one of the last of the old school of haute couture, where gorgeous clothes were made for a woman to live in, not to decorate her,” fashion journalist Dana Thomas wrote in the Washington Post in 1995.

The precociously talented, darkly handsome 6-foot-6 designer was only 25 when he opened his own atelier in Paris in 1952. His debut collection was one of the earliest ready-to-wear, high-end fashion lines.

“Paris had been occupied by the Nazis, and French fashion had been pretty much beaten into the ground,” said Valerie Steele, director of New York’s Fashion Institute of Technology Museum. “He was one of the leading French courtiers in a period in which couture made a triumphant resurgence.”

Givenchy thought mix-and-match separates, including interchangeable dresses, light skirts and chic tops, offered women more versatility with their look and choices in creating their own style. Operating on a shoestring budget, he created a handful of styles out of inexpensive men’s shirting material for his first collection and asked customers to select their preferred fabric.

The crisp, embroidered full-ruffled “Bettina” blouse (named in honor of the late model Bettina Graziani) was an instant hit. By the end of the first day, the store reportedly rang up 7 million francs (about $14,000 in today’s dollars).

Givenchy’s fashioning of and relationship with Hepburn was often regarded as his broader cultural breakthrough. The couturier first met Hepburn in 1953 after she had been cast in the romantic comedy “Sabrina.” She played a Long Island chauffeur’s tomboy daughter who studies in Paris and returns as a chic, sophisticated woman. Hepburn thought it would be fitting for her character to wear authentic Parisian couture.

When told he had the opportunity to costume Hepburn, Givenchy was under the impression that it was a different famous Hepburn — Katharine Hepburn. Despite having received acclaim in the U.S. for her starring role in “Roman Holiday,” which would eventually earn Audrey Hepburn an Oscar, the film had not yet been released overseas. At the time, the waifish actress was still a relatively unknown star in Europe.

Givenchy was shocked when the doe-eyed beauty walked into his studio. Scrambling to complete his next collection, he told Hepburn he was too busy to design original pieces for her but that she could select items from his previous season’s collection, including the belted ivory dress she wore to the 1954 Academy Awards.

“She gave a life to the clothes — she had a way of installing herself in them that I have seen in no one else since, except maybe the model Dalma,” Givenchy told Vanity Fair in 1995.

“Sabrina” went on to receive the Oscar for costume design, although head designer Edith Head failed to acknowledge Givenchy’s contributions during her acceptance speech. According to Head’s biographer, David Chierichetti, Head banked on the fact that Givenchy was “such a gentleman he would not make a fuss.” He didn’t.

Hepburn was furious. From that point on, she insisted Givenchy costume her in subsequent films including “Funny Face,” “Breakfast at Tiffany’s” (including the famous black dress) and ­“Charade.” She became his greatest fashion ambassador on screen and off.

Count Hubert James Marcel Taffin de Givenchy was born in Beauvais, France, on Feb. 21, 1927, to a prosperous family.

Once, when asked if his talent was God-given or self-made, Givenchy replied: “Maybe He give[s] you the energy and belief, but you must yourself have these things, too.”

God, added the designer, “doesn’t make the collections for you four times a year.”