Nicole Kidman and her husband, Keith Urban, were among the first celebrities to arrive inside the Great Hall at the Metropolitan Museum of Art on Monday for the Costume Institute benefit, honoring the designer Karl Lagerfeld. The couple was accompanied by Baz Luhrmann and his wife, Catherine Martin.

For the cameras, Ms. Kidman, with her long, strawberry blond locks, in a swath of peachy fabric, seemed to float toward Mr. Luhrmann’s side, in front of a towering centerpiece featuring hundreds of one-liter plastic bottles sourced from a recycling plant.

The light of many flash bulbs reflected off the bottles, lighting Mr. Luhrmann’s face as he fluffed Ms. Kidman’s train, gesturing with his hands, softly, toward her face. Ms. Kidman, who starred in Mr. Luhrmann’s films “Moulin Rouge!” and “Australia,” poked her chin up, meeting the director’s hand in midair.

The role of muse is one Ms. Kidman knows well: She was also one of Mr. Lagerfeld’s muses, though she humbly deflected about the title when asked if she considered herself as such, preferring to talk about how much he taught her.

“I stood there, you know, in my lingerie while he designed my dress,” Ms. Kidman said about Mr. Lagerfeld, who died in 2019 at 85, as she exited the exhibition and headed to the cocktail party in the American Wing of the museum. She clutched the train of her dress, designed by Mr. Lagerfeld for a Chanel No. 5 commercial Mr. Luhrmann directed. “Karl knew me and he was able to design for me, but he was also really playful and fun. It was just lovely in the same way as being around someone like Stanley Kubrick.”

Supermodels like Kate Moss cherished the intimacy they shared with Mr. Lagerfeld. Ms. Moss recalled working with the designer, as well as his infamous largess.

“To sit at the desk with Karl Lagerfeld as he sketched was the most incredible thing,” Ms. Moss said, as she entered the exhibit with her daughter, Lila Moss, wearing a Fendi dress. “He was so generous with his passion.”

Naomi Campbell, who walked in Mr. Lagerfeld’s runway shows and shot ad campaigns with him, also relished the bond she shared with Mr. Lagerfeld. As she walked through the exhibition, “Karl Lagerfeld: A Line of Beauty,” her knee-length dark hair contrasted with the stark white walls.

“If I could describe our relationship, it was fun, witty, intelligent, never a dull moment, so creative, risk-taking and caring.” she said, wearing a satin pink and silver Chanel dress from the 2010 couture collection.” One thing she loved about Mr. Lagerfeld? “He was very honest: He did not suffer fools.”

Ms. Campbell is proud of having been Mr. Lagerfeld’s muse because it allowed her to watch him conceive an idea and bring it to life, she said.

“It is an honor to be a muse,” Ms. Campbell said while a man holding a satin pink purse that matched her dress on a pillow stood several feet away. “It’s an honor to be a part of, to watch something transpire and watch what it turns into.”

Unlike Ms. Campbell, Gisele Bündchen, who wore archival Chanel from the 2007 bridal collection, has never considered herself a muse. She felt too tomboyish to see herself in that context, but she has muses of her own, she said.

“My muse is my mom and my grandma because they are incredible women who show me the values that carry me throughout my life,” Ms. Bündchen said as she walked through the exhibit in a feathery white Chanel cape with a train that dragged a foot behind her and laid over a sequined white Chanel dress.

The Oscar-nominated actor Bryan Tyree Henry said that he also considered his mother his muse. “My mother was my muse for most of my life, still is,” said Mr. Henry, who wore a collaborative piece from the Karl Lagerfeld bridal collection. “She was one of the most fashionable people I ever saw. From her jewelry to her rings or shoes, I was enamored with everything that she picked and how she walked in this world.”

The designer Tom Ford believes muses are important, even more so for male designers of women’s clothes. “Oh my God, I have so many muses,” Mr. Ford said as he walked past a row of waiters in white tuxedos and away from the bar, fizzy drink in hand. “I would say I have two main muses, Carine Roitfeld and Lisa Eisner. They represent very different sides of my own personal taste, and both were quite different.”

While Mr. Ford can narrow it down to two women, the Nigerian singer Tems, who wore a feathered Robert Wun gown, said she finds creative inspiration in everyone.

“We gain inspiration from everybody — it’s a universal thing.” Tems said, while chatting with Gabrielle Union, who wore a red Prada get-up. “We are all connected. You can see somebody right now, and then you gain inspiration from that. We are all muses in our own right, whether we know it or not.”