Mario Paglino and Gianni Grossi, designers who turned Barbie dolls into one-of-a-kind works of art that sold for thousands of dollars, including one that fetched more than $15,000 at a charity auction, died on July 27 in Italy. Mr. Paglino was 52; Mr. Grossi was 54.

The Italian news service ANSA reported their deaths, in a car collision with another vehicle that was going the wrong way on the A4 Turin-Milan highway.

The two men, who married in New York City in 2022, lived and worked together in Novara, west of Milan. They were celebrities in the global Barbie doll-collecting community, which is vast and has numerous Facebook groups, some with more than 100,000 members.

Depending on their interests, fans “buy Barbies that have been created by Mattel, or they buy limited-edition and one-of-a-kind Barbies that doll artists make,” Kim Culmone, the head of design for dolls at Mattel, said in an interview.

“There are different levels of people who do this sort of work,” she added. “And Gianni and Mario really were just a cut above.”

Mr. Paglino, a fashion designer, and Mr. Grossi, a graphic art director, were hailed by collectors for their meticulous handiwork — the ruffles and extravagant bows, the embroidery, appliqué, crystals, rhinestones, paillettes and beading on silk, satin and tulle — as well as their unswerving attention to detail and their deep knowledge of fashion and art history. Most of the Barbies from their atelier sold for $2,000 to $3,000.

One well-cloaked Barbie of their devising looked to be straight out of a Velazquez painting. Mr. Grossi and Mr. Paglino also created a line of Barbies wearing finery inspired by the works of well-known artists, including Vincent van Gogh (“Sunflowers” and “Irises”), Piet Mondrian (“Composition With Red, Blue and Yellow”), Gustav Klimt (“Portrait of Adele Bloch-Bauer I”), Andy Warhol (“Marilyn Diptych”) and Frida Kahlo (“The Two Fridas”). In a tribute to Jackson Pollock’s “Convergence,” they created a Barbie gown that echoed the artist’s drip-painting technique.

Here and there, dresses also made subtle references Coco Chanel and Elsa Schiaparelli.

Some of Mr. Paglino and Mr. Grossi’s creations were inspired as much by pop culture as by art. The men designed look-alike Barbies to pay tribute to show-business personalities like Sarah Jessica Parker, Victoria Beckham, Lady Gaga and Sophia Loren. They conjured several different Barbies for their favorite star, Madonna, and proudly watched from the audience of “The Graham Norton Show” in Britain as one of the dolls was presented to her in 2012.

After they died, Madonna dedicated the 40th anniversary reissue of her hit “Dress You Up” to the designers’ memory, thanking them “for dressing up so many of your creations in Madonna iconic looks over the years,” Rolling Stone magazine reported.

Gianni Grossi was born on Nov. 27, 1970, and grew up in Biella, Italy, a city northeast of Turin, where his mother, Marissa Grossi, worked in the textiles industry. She survives him, as does a half sister, Luisa.

Mario Paglino was born on June 30, 1973, in Turin, the oldest of three sons of Maria Concetta (Albano) Paglino and Guiseppe Paglino, who ran a laundry service. They survive him, along with his brothers, Max and Matteo Paglino.

For Mr. Grossi, the fascination with Barbie began early; as a child, he often played with a little girl who had several Barbie dolls, according to his family.

Matteo Paglino recalled in an email that his brother Mario’s interest in Barbie dolls began as a 9-year-old. After helping with household chores and much pleading, Mario was given the coveted Barbie Dream Date doll. But when children at school taunted him, his father took the doll away.

Years later, Mr. Grossi presented Mr. Paglino with the same doll, reviving his enthusiasm for Barbies.

The two men met in 1997 and soon became a couple. They established their company, Magia2000, in 1999. Magia means magic in Italian; it also contains the first few letters of each founder’s first name.

Mr. Paglino and Mr. Grossi generally worked with Barbies that were made from silkstone, a composite material with a smooth, porcelain-like appearance. A blend of resin, quartz and sand, it produces a heavier, more substantial doll than those typically found in the aisles of chain stores. (Mattel generally uses silkstone for its Barbie Fashion Model Collection, a higher-priced line aimed at adult doll collectors.)

Magia2000’s Barbies got a full makeover. Their factory face paint was removed, and they were given a whole new look with the aid of acrylic paint and watercolor pencils. Their hair was restyled or removed entirely and replaced with a different shade of nylon tendrils, a process called re-rooting.

Mr. Paglino designed and made the clothing; he also did the hairstyling. Mr. Grossi sewed the beading, embroidery and appliqués by hand. (Swarovski crystals figured prominently.) He also handled the dolls’ accessories and worked on photography and marketing for the company.

The men typically produced four collections a year, each with close to 60 dolls. Among them: the Pink Collection (the name says it all); Bye, Bye, Summer 2018, an assemblage of dolls dressed in outfits from places that Mr. Paglino and Mr. Grossi had visited on vacation; and the Fairy Tale Collection, replete with heroines and villainesses.

“Mario and Gianni had a very couture approach — very detailed — with impeccable gown construction, an eye for color and print and pattern, and a sense of the dramatic and theatrical,” Ms. Culmone, of Mattel, said. “But they were also able to do very realistic interpretations of an existing person with a modern, everyday look.”

The men partnered with Mattel on a handful of projects. For the toymaker’s Inspiring Women project, honoring historical role models, they designed one-of-a-kind dolls to celebrate the achievements of more than a dozen American, European, South American and Asian athletes, educators, entrepreneurs and artists.

They also made dolls for special events and exhibits, and accepted commissions.

When Cheryl Burnett, a retired bank employee in suburban Houston, was celebrating her 40th wedding anniversary, she asked the couple to replicate her wedding dress and hairdo on a Barbie doll, and the tuxedo worn by her husband, Charlie, on a Ken doll.

“I’m a superfan,” Ms. Burnett said. She acquired her first Magia2000 Barbie in 2012, when she made the winning bid of $4,000 at a charity auction during the annual National Barbie Doll Collectors Convention, which took place that year in Garden Grove, Calif. The next year, when the convention was held in New Orleans, she prevailed again at the auction, paying $10,000 for Magic Carnival of Venice, a Barbie that “looked like a Marie Antoinette type of doll,” Ms. Burnett said.

By her count, she now owns 244 Barbies made by Mr. Paglino and Mr. Grossi.

At the convention’s charity auction in 2015, in Arlington, Va., Ms. Burnett bid $15,000 for Magic Wanda, a Barbie cloaked in a blue gown with gold sequins, only to have a rival from Australia outbid her, for $15,250. “At that point, my husband looked at me and said, ‘Really?’ And I said, ‘OK, we’ll let her have it,’” Ms. Burnett recalled.

“It’s hard to describe the detail and beauty that went into those dolls,” she added. “You know how some people collect paintings or sculpture? These Barbies are works of art.”

Barbie may have been their 11½ -inch-tall muse, but Mr. Paglino and Mr. Grossi also designed clothing and accessories and did the hair and makeup for other fashion dolls.

In 2023, for example, they dressed 12-inch-tall figures in high-fashion outfits inspired by their home countries in collaboration with Integrity Toys, a company that specializes in collectible dolls.

“When I make dolls for Barbie,” Ms. Culmone said, “I have a group of artists who specialize in pattern-making, embroidery and beading. Someone else specializes in face painting. Someone else specializes in hair design. Think about the rarity of finding a pair of individuals who could take all those parts of doll — coming up with the vision, the fashion design, the pattern-making, the sample-making, the embroidery, the hair design, the hair embellishments, the shoe creation.”

“These are two people who played a big role in our community,” she added. “Because of them, our community is better. My design team is better. Barbie is better.”