Lee Radziwill, the free-spirited former princess who shared the qualities of wealth, social status and ambition with her older sister, Jacqueline Kennedy Onassis, but who struggled as an actor, decorator and writer to share her sister’s aura of success, died on Friday at her home in Manhattan. She was 85.

Her daughter, Anna Christina Radziwill, confirmed the death, citing natural causes.

It cannot have been easy living in the shadow of one of the world’s most famous women, the wife of President John F. Kennedy, and Mrs. Radziwill was hardly immune to competitive instincts. Jackie Kennedy had helped create the mystique of the thousand days of Camelot — a woman who had made her new home a place of elegance and culture, who had brought babies into the White House for the first time in the 20th century.

Mrs. Radziwill, the wife of a Polish émigré nobleman, Prince Stanislas Radziwill, was an international socialite and fashion icon who for years was on lists of the world’s best-dressed women. Like Jackie, she had cultivated passions for painting, music, dance and poetry. She made several attempts for professional recognition, but achieved only pale reflections of the spotlight on her sister.