Marella Agnelli, née Caracciolo di Castagneto, was born in Florence, a daughter of Don Filippo Caracciolo, 8th Prince of Castagneto, a member of an aristocratic Italian family, and his American wife Margaret Clarke. Her brother Carlo Caracciolo founded the newspaper La Repubblica. She studied art in Paris, and served as an assistant to photographer Erwin Blumenfeld in New York City. She worked as an occasional editor and photographic for Vogue magazine. In 1953, she married Giovanni Agnelli, the heir to the Fiat dynasty, with whom she had two children. She was a member of Truman Capote's circle of wealthy and stylish women he called the "Swans," and came to epitomize the "Beautiful People" of the 1960s. She was an art collector and patron of the arts, and opened an art gallery to showcase the family's collection of works by Picasso, Matisse, Renoir, and many others. She also waso an avid gardener, and wrote several books on the subject, some illustrated with her own photos, including Gardens of the Italian Villas (1987) and The Agnelli Gardens at Villar Perosa (1998).