Nancy Sandra Sinatra Jr (born June 8, 1940, in Jersey City, New Jersey) is an American singer and actress. She is the daughter of the legendary singer Frank Sinatra and his first wife Nancy Barbato.

Her career peaked in the late 1960s with a string of pop music hits. Her best-known hit, These Boots Are Made for Walkin' - which popularized and made her synonymous with Go-Go boots - was written by Lee Hazlewood. These Boots... has been covered by many artists such as Geri Halliwell, Dave Mustaine's Megadeth, Jessica Simpson, Lil' Kim, Little Birdy, Billy Ray Cyrus, Crispin Hellion Glover and KMFDM.

Nancy also co-starred in a number of films, including Roger Corman's The Wild Angels with Peter Fonda and Bruce Dern, and Speedway with Elvis Presley, made guest appearances on The Ed Sullivan Show, and starred in a number of television specials, most notable among them the 1967 Emmy Award-winning special "Movin' with Nancy", in which she appeared with her father and his Rat Pack pals Dean Martin and Sammy Davis, Jr.. In the 1970s, she slowed down her musical activity and ceased acting in order to concentrate on being a wife and mother. She returned to the studio in 1981 to record a country album with Mel Tillis called, Mel & Nancy.

At the age of 54, she posed for Playboy in their May 1995 issue, released a new CD, One More Time, and made guest appearances on TV shows to promote the new material.

Most Recently, the song Bang Bang (My Baby Shot Me Down) was used on the soundtrack of Quentin Tarantino's hit Kill Bill.