Patrick Demarchelier, a photographer whose work helped define fashion and celebrity in the late 20th and early 21st centuries, died on Thursday. He was 78.
His death was announced on his Instagram page. The announcement did not say where he died or specify the cause.
The personal portraitist of Diana, Princess of Wales, and the first non-Briton to become an official royal photographer, Mr. Demarchelier was most famous for his work with Vogue and Harper’s Bazaar, and he was the subject of a major bidding war between the glossies. Indeed, he became so synonymous with Vogue that his name made a cameo in the 2006 film “The Devil Wears Prada,” from which “Get me Patrick” was a much-quoted line.
“Patrick takes simple photographs perfectly, which is of course immensely difficult,” Anna Wintour, the editor of Vogue, wrote in a 2015 essay for a Christie’s auction of his work. “He makes attractive women look beautiful and beautiful women seem real.”
An ability to combine ease and elegance set his work apart. His photographs of Diana often had an unstudied aspect that crystallized the princess’s informal personality, such as a snap of her taken in 1990 sitting on the floor in a strapless white gown and diamond tiara, hugging her knees. A photograph of Madonna for the cover of Vogue in 1989 captured her in a white bathing suit laughing and looking over her shoulder in a pool, as though she had just popped up from a swim.
“I like to do the pictures before people get too self-conscious,” Mr. Demarchelier told the actor Keira Knightley for Interview magazine. “I like to be spontaneous and get a shot before the subject thinks too much about it.”
Born in 1943 (most sources give the date as Aug. 21), Patrick Demarchelier grew up in Le Havre, France. With no formal training in photography, he started taking pictures of his friends and moved to Paris at age 20, though he made his career in the United States. His work as an assistant to Hans Feurer, a Swiss photographer who worked with Vogue, brought him to the attention of the magazine, and he began his relationship with Vogue even before he joined a girlfriend in New York in 1975.
He had a long creative partnership with the fashion editor Grace Coddington at both British and American Vogue. But it was his cover shot of Linda Evangelista for the September 1992 issue of Harper’s Bazaar, one eye hidden by an arm holding up the third “A” of “Bazaar,” that declared the arrival of a new editor, Liz Tilberis, and a new aesthetic: clean, glamorous and unforced.
Mr. Demarchelier’s rise in magazines coincided with the emergence of supermodels and celebrity covers, and he was an integral part of creating both. He recommended Kate Moss to Calvin Klein, caught Cindy Crawford being carried on a surfboard by a dozen adoring dudes and, in 1992, helmed the 100th-anniversary cover of Vogue, featuring 10 of the biggest modeling names — Naomi Campbell, Claudia Schiffer and Christy Turlington among them — in white shirts knotted at their waists and jeans, hanging out on a ladder like a gorgeous house-painting team on a lunch break.
Like Princess Diana, Madonna was attracted by Mr. Demarchelier’s relaxed approach, and he became one of her favorite photographers. He shot her in a black leather baseball cap and vest, arms crossed and tucked under her armpits, cigarette dangling from her lips, for her 1990 single “Justify My Love.”
He got Janet Jackson to pose topless for the cover of Rolling Stone, an unnamed man’s hands clasping her breasts from behind, in an image that signaled her emergence as an independent musical power.
With a sweep of graying hair, worm eyebrows and a squinting grin, Mr. Demarchelier was not above using his own Gallic charm — and a patented form of Franglais — to get a subject to do his bidding.
“No one understands anything he says,” Ms. Coddington told The New York Times in 2016. “But he calls the models ‘bebe’ and says ‘fabulous’ and ‘diveeeeene,’ and he makes them feel beautiful.”
Beyond magazines, Mr. Demarchelier worked with such brands as Christian Dior, for which he also did a book, “Dior: Couture,” in 2011, as well as Ralph Lauren, Chanel and Giorgio Armani. He photographed the Pirelli calendar three times: in 2005 (in Brazil), 2008 (China) and 2014 (for the calendar’s 50th anniversary, in conjunction with the photographer Peter Lindbergh and featuring — again — bevies of supermodels).
In 2007, the French Ministry of Culture named him an Officer of the Order of Arts and Letters, and the Council of Fashion Designers of America gave him its Founder’s Award. In 2008 he appeared in the first “Sex and the City” movie as himself, photographing Sarah Jessica Parker’s Carrie Bradshaw in wedding gowns for, natch, Vogue. The next year the Petit Palais in Paris showed a retrospective of his work entitled “The Cult of Personality.”
He is survived by his wife, Mia; three sons, Gustaf, Arthur and Victor; and three grandchildren.
“I like to photograph the positive way of life,” Mr. Demarchelier told The Times in 2016. “I like the beauty, the beauty inside.”