Maria de Lourdes Villiers "Mia" Farrow ( mə-REE-ə dee LOORDZ VIL-yərz FARR-oh; born February 9, 1945) is an American actress. She first gained notice for her role as Allison MacKenzie in the television soap opera Peyton Place and gained further recognition for her subsequent short-lived marriage to Frank Sinatra. An early film role, as Rosemary in Roman Polanski's Rosemary's Baby (1968), saw her nominated for a BAFTA Award and a Golden Globe Award for Best Actress. She went on to appear in several films throughout the 1970s, such as Follow Me! (1972), The Great Gatsby (1974), and Death on the Nile (1978). Her younger sister is Prudence Farrow.

Farrow was in a relationship with actor-director Woody Allen from 1980 to 1992 and appeared in thirteen of his fourteen films over that period, beginning with A Midsummer Night's Sex Comedy (1982). She received numerous critical accolades for her performances in several Allen films, including Golden Globe Award nominations for Broadway Danny Rose (1984), The Purple Rose of Cairo (1985), and Alice (1990), and a BAFTA nomination for Hannah and Her Sisters (1986). After separating from Allen in 1992, she made public allegations that he had sexually assaulted their seven-year-old adopted daughter, Dylan. Allen was never charged with a crime and has vigorously denied the allegation. These claims received significant renewed public attention in 2013 after Dylan recounted the alleged assault in an interview that year.

Since the 2000s, Farrow has made occasional appearances on television, including a recurring role on Third Watch (2001–2003). She has also had supporting parts in such films as The Omen (2006), Be Kind Rewind (2008), and Dark Horse (2011). Farrow is also known for her extensive work as a UNICEF Goodwill Ambassador. She is involved in humanitarian activities in Darfur, Chad, and the Central African Republic. In 2008, Time magazine named her one of the most influential people in the world.