Mathilde Favier was far more than a familiar face at Dior fashion shows. Her career was rooted in a remarkable Parisian family whose connections to couture, jewelry and high society stretched across generations.
Favier, Dior’s longtime director of public relations, died at 57 on August 17, 2026, in a car accident in western France. Her longtime partner, French film producer Nicolas Altmayer, also died in the crash. Dior and leading figures across the fashion industry subsequently paid tribute to her warmth, professionalism and extraordinary contribution to the house.
Behind that celebrated career was a family deeply intertwined with French fashion. From her mother’s social circle to her uncle’s work with Karl Lagerfeld and her half-sister’s leadership at Dior, Favier was surrounded by influential figures from an early age.
Her Children
Favier was the mother of two children, Héloïse and Carlo Agostinelli, from her first marriage to financier Robert Agostinelli.
Héloïse Agostinelli, born around 1999, developed a public profile spanning fashion, modeling and television. She has been associated with both Paris and London and appeared on the British reality series Made in Chelsea. Her upbringing placed her naturally within the fashion and society circles where her mother was a prominent presence.
Carlo Agostinelli, born around 2001, followed a very different professional route. He played Division I soccer at Stanford University after attending Harrow School in England. He also established The Eleven Foundation, which uses football as a vehicle for charitable work.
The siblings therefore inherited their mother’s connection to elite circles while developing careers of their own.
Her Mother
Mathilde’s mother, Françoise Favier, played an important role in shaping the environment in which her daughters grew up.
Favier was raised in Paris and became immersed in a sophisticated cultural world populated by influential artists, designers and society figures. Accounts of her upbringing have highlighted the importance of Parisian savoir-vivre and the people who surrounded the family.
That background helps explain why Mathilde later appeared so naturally at the center of luxury fashion. Her understanding of fashion was not simply professional training; it was part of the world she had known since childhood.
Gilles Dufour
One of the strongest links between Favier’s family and haute couture was her maternal uncle, Gilles Dufour.
Dufour was a major figure in Karl Lagerfeld’s fashion circle and worked closely with him at Chanel. His career gave Mathilde and her sister Victoire an early doorway into the fashion business.
According to the South China Morning Post, Mathilde and Victoire began their careers at Chanel alongside their uncle.
That early experience was significant. Rather than entering fashion as outsiders, the sisters learned the workings of a major Parisian fashion house from close range.
Victoire de Castellane
Mathilde’s half-sister, Victoire de Castellane, went on to become one of the most recognizable names in luxury jewelry.
De Castellane has served as Dior’s creative director of fine jewelry since 1998, developing a distinctive visual language that has become closely associated with the house.
Her career represents another remarkable branch of the family’s fashion legacy. While Mathilde became known for communications and public relations, Victoire established herself through design.
Their professional paths began together at Chanel but eventually led to influential positions within Dior.
A Dior Connection
Mathilde joined Dior in 2011 after previously working at Prada. Over the following years, she became one of the key people responsible for maintaining relationships between Dior and its international celebrities, clients and ambassadors.
Her role required considerably more than arranging appearances. She became an important bridge between the fashion house and the personalities who helped define its public image.
Her 2024 book, Living Beautifully in Paris, offered another window into the world she inhabited. The book explored Parisian life and included contributions from people within her extensive social and cultural network.
Her Partner
At the time of her death, Favier was in a long-term relationship with Nicolas Altmayer, a prominent French film producer.
Altmayer, 61, died in the same August 17 crash. French authorities said the couple’s vehicle collided with a truck while overtaking another vehicle.
Their deaths united two influential cultural worlds in an unexpected tragedy: French cinema and international luxury fashion.
Final Tributes
The response from Dior underscored the importance Favier had acquired during her years at the house.
Delphine Arnault, CEO of Christian Dior Couture, remembered her as an exceptional professional and loyal friend. LVMH chairman Bernard Arnault also expressed his sadness, while Dior creative director Jonathan Anderson described Favier as a warm, positive presence and a person closely connected with the spirit of couture.
Those tributes also brought attention back to her family.
Mathilde Favier’s story cannot be separated from the fashion world she helped shape. Her mother introduced her to an influential Parisian social environment, her uncle provided an early connection to couture, and her sister became a major creative force at Dior.
Yet Favier ultimately created her own place within that world.
For more than a decade, she helped Dior communicate with some of the most recognizable names in global culture. Her children have since pursued their own directions, while Victoire de Castellane continues the family’s creative connection to Dior.
