Penelope Tree (born 1950) is a former Anglo-American model.

She was the only child of Marietta Peabody Tree, a socialite and Democratic political activist, and Ronald Tree, a bisexual journalist, investor and MP. Tree is a great-granddaughter of American retailer Marshall Field and of American educator Rev. Endicott Peabody.

Tree's family objected to her career as a model, and when she was first photographed at the age of 13 by Diane Arbus, her father vowed he would sue if the pictures were published.
Cecil Beaton also photographed Tree's elfin face, one that made "The Tree" a match for "The Twig" in the 1960s. By the time Diana Vreeland sent her to Richard Avedon, she was seventeen and her father had relented. David Bailey described Penelope as 'an Egyptian Jimminy Cricket". In 1967, she moved into Bailey's flat in London's Primose Hill neighbourhood. It became a hang-out for spaced-out hippies during the "Swinging Sixties" who, Bailey recalled, would be "smoking joints I had paid for and calling me a capitalist pig!" In another famous quote, John Lennon, asked to encapsulate Tree in three words, called her, "Hot, Hot, Hot, Smart, Smart, Smart!" She has been extensively compared to The Beatles for inspiring the swinging 60's movement and for galvanizing a generation of young American females. Scars from late-onset acne ended her career in the early 1970s: "I went from being sought-after to being shunned because nobody could bear to talk about the way I looked."

In 1974, Bailey and Tree split up and she moved to Sydney, Australia. She appeared in the British comedy film The Rutles in 1978. She is the half-sister of US author Frances FitzGerald and a niece of former Massachusetts governor Endicott Peabody.

She has been married twice, once to the South African rock musician Ricky Fataar (who was a member of The Flames, The Rutles, and the Beach Boys). She has two children, Paloma Tree Fataar (a graduate of Bard College and a student of Tibetan Buddhism and music), and Michael, by her second marriage.

She currently works for Lotus Outreach, a charity which works in Cambodia in partnership with local grassroots women's organisations to give girls from the very poorest families the wherewithal to go to school.