Reports: Lee Radziwill, sister of Jackie Kennedy Onassis, dies at age 85

Lee Radziwill, the fashionable socialite and sister of Jackie Kennedy Onassis, has died at age 85. 

Close family friend Mathilde Favier, the public relations director for Christian Dior, confirmed Radziwill's death on Instagram: "Sad Saturday morning news: Lee Radziwill just passed away."

"A page is gone," Favier wrote. "She, being great friend with my uncle Gilles, introduced me to the father of my kids, she witnessed our wedding, we gave her first name to our daughter Heloise-Lee."

Her cause of death is unknown. 

Radziwill was born Caroline Lee Bouvier in 1933 to stockbroker John Vernou Bouvier III and socialite Janet Norton Lee. She was the younger sister of former first lady Jackie and sister-in-law of President John F. Kennedy. Her daughter-in-law, Carole Radziwill, appeared on several seasons of "The Real Housewives of New York."

Related: New book looks at fabulous lives, rivalry of the Bouvier sisters, Jackie and Lee

Radziwill briefly worked as an actress, starring in the film "Laura," before becoming an interior designer and a public relations executive for Italian fashion house, Giorgio Armani.

But, the fashion icon, who was named to the International Best Dressed List Hall of Fame in 1996 and gallivanted with the likes of Truman Capote and Andy Warhol, will forever be remembered for her style and relation to her older sister. Lee and Jackie were bona fide "it girls" in the 1960s.

Favier told WWD that Radziwill's death marked "the end of an era."

"She was the height of elegance, a true icon — an incredibly attractive woman who always adapted to whatever the circumstance. She was never overdressed or underdressed," Favier said. "She was incredibly elegant and inspiring, and always ahead of her time because she was a fashion visionary. It’s very sad. It’s the end of an era."

Radziwill married and divorced three times. She was previously wed to publishing executive Michael Temple Canfield, Polish aristocrat Prince Stanislaw Albrecht Radziwill, whom she shares two children – Prince Anthony and Princess Anna Christina – and film director Herbert Ross.

Her son Anthony died of cancer at age 40 in 1999, while her sister died of cancer in 1994 at age 64.

Designer Tory Burch, who styled her fall/winter 2018 collection after the icon, paid tribute on Twitter: "We are heartbroken and I will miss our dear friend. Rest In Peace, Lee Radziwill."

Related: Tory Burch's Fashion Week show was inspired by Jackie O's sister Lee—and fit for Duchess Kate