Peggy Guggenheim (1898-1979) was an American art collector .

Born Marguerite Guggenheim on August 26, 1898 to a wealthy New York City family, she was the daughter of Benjamin Guggenheim, who went down with the Titanic in 1912 and the niece of Solomon Guggenheim, who would establish the Solomon R. Guggenheim Foundation.

At the age of 21 Peggy Guggenheim inherited a small fortune, but as the poorer branch of the family, it was an amount far less than the vast wealth of her father's siblings.

She was a clerk in an avant-garde bookstore when she first became enamored of the members of the bohemian artistic community. In 1920 she went to live in Paris, France. Once there, she became friendly with avant-garde writers and artists, many of whom were living in poverty in the Montparnasse Quarter of the city. Man Ray photographed her, and he along with Constantin Brancusi, Marcel Duchamp all were friends whose art she promoted.

Ms. Guggenheim got married for the first time to Laurence Vail, a Dada sculptor and writer. In 1938 she opened a gallery for modern art in London featuring Jean Cocteau and began to collect works of art. After the outbreak of World War II, she purchased as much abstract and Surrealist art as possible. When finished, she had acquired 10 Picassos, 40 Ernsts, 8 Mirós, 4 Magrittes, 3 Man Rays, 3 Dalís, 1 Klee, and 1 Chagall.

After acquiring one of the most important collections of Modern art in private hands she returned to New York where, in 1942, she opened another gallery, called Art of This Century. As a result of her interest in new artists she was instrumental in advancing the careers of many important modern artists, including the American painter Jackson Pollock, and the German-French painter Max Ernst, whom she married in 1942.

After the War, and her 1946 divorce from Max Ernst, she returned to Europe and eventually established her collection in the large Palazzo Venier dei Leoni in Venice, Italy where it became one of the few European collections of modern art to promote a significant amount of works by Americans. By the early 1960s, Peggy Guggenheim had stopped collecting art and began to concentrate on presenting what she already owned. She loaned out her collection to museums throughout Europe and America, including the New York museum named after her uncle, Solomon R. Guggenheim. Eventually, she decided to donate her large home and her collection to the Solomon R. Guggenheim Foundation on her death.

The Peggy Guggenheim Collection is the most important museum in Italy for European and American art of the first half of the 20th century. Pieces in her collection embrace Cubism, Surrealism and Abstract Expressionism.

A play by Lanie Robertson based on Peggy Guggenheim's life, Woman Before a Glass, opened at the Promenade Theatre on Broadway, New York on March 10th, 2005. Mercedes Ruehl plays Peggy Guggenheim.

Known as The Mistress of Modern Art, Peggy Guggenheim lived in Venice until her death in Padua, Italy on December 23, 1979. She is interred in the Nasher Sculpture Garden on her estate, buried next to her beloved dogs.