Nancy Sandra Sinatra (born June 8, 1940) is an American singer. She is the elder daughter of Frank Sinatra and Nancy Sinatra (née Barbato) and is known for her 1965 signature hit "These Boots Are Made for Walkin'".

Nancy Sinatra began her career as a singer in November 1957 with an appearance on her father's ABC-TV variety series but initially achieved success only in Europe and Japan. In early 1966 she had a transatlantic number-one hit with "These Boots Are Made for Walkin'". A TV promo clip from the era features Sinatra in high boots, accompanied by colorfully dressed go-go dancers, in what is now considered an iconic Swinging Sixties look. The song was written by Lee Hazlewood, who wrote and produced most of her hits and sang with her on several duets. As with all of Sinatra's 1960s hits, "Boots" featured Billy Strange as arranger and conductor.

Between early 1966 and early 1968, Sinatra charted on Billboard's Hot 100 with 14 titles, ten of which reached the Top 40. In addition to "These Boots Are Made for Walkin'", defining recordings during this period include "Sugar Town", "Love Eyes", the transatlantic 1967 number one "Somethin' Stupid" (a duet with her father), two versions of the title song from the James Bond film You Only Live Twice (1967), several collaborations with Lee Hazlewood – including "Summer Wine", "Jackson", "Lady Bird" and "Some Velvet Morning" – and a non-single 1966 cover of the Cher hit "Bang Bang (My Baby Shot Me Down)", which features in the opening credits of Quentin Tarantino's 2003 film Kill Bill Volume 1. In 1971 Sinatra and Hazlewood achieved their first collaborative success in the UK singles chart with the no. 2 hit "Did You Ever?", and the 2005 UK no. 3 hit by Audio Bullys, "Shot You Down", sampled Sinatra's version of "Bang Bang".

Between 1964 and 1968 Sinatra appeared in several feature films, co-starring with Peter Fonda in Roger Corman's biker-gang movie The Wild Angels (1966) and alongside Elvis Presley in the musical drama Speedway (1968). Frank and Nancy Sinatra played a fictional father and daughter in the 1965 comedy Marriage on the Rocks.