Nancy Sue Wilson (February 20, 1937 – December 13, 2018) was an American singer whose career spanned over five decades, from the mid-1950s until her retirement in the early 2010s. She was especially notable for her single "(You Don't Know) How Glad I Am" and her version of the standard "Guess Who I Saw Today". Wilson recorded more than 70 albums and won three Grammy Awards for her work. During her performing career, Wilson was labeled a singer of blues, jazz, R&B, pop, and soul; a "consummate actress"; and "the complete entertainer". The title she preferred, however, was "song stylist". She received many nicknames including "Sweet Nancy", "The Baby", "Fancy Miss Nancy" and "The Girl With the Honey-Coated Voice".

Nancy Wilson was born on February 20, 1937, in Chillicothe, Ohio, to Olden Wilson, an iron foundry worker, and Lillian Ryan.

Wilson attended Burnside Heights Elementary School and developed her singing skills by participating in church choirs. She attended West High School in Columbus, Ohio where she won a talent contest and was rewarded with a role as a host for a local television show. She then went on to attend Ohio's Central State University where she pursued her B.A. degree in education.

When Wilson met Julian "Cannonball" Adderley, he suggested she move to New York City for career opportunities. In 1959, she moved to New York to try to hire Adderley's manager and get a contract with Capitol Records. Within four weeks of her arrival in New York she got her first big break, a call to fill in for Irene Reid at "The Blue Morocco". The club booked Wilson on a permanent basis; she was singing four nights a week and working as a secretary for the New York Institute of Technology during the day. John Levy sent demos of "Guess Who I Saw Today", "Sometimes I'm Happy", and two other songs to Capitol. Capitol Records signed her in 1960.

Wilson's debut single, "Guess Who I Saw Today", was so successful that between April 1960 and July 1962 Capitol Records released five Nancy Wilson albums. Her first album, Like in Love, displayed her talent in rhythm and blues. Adderley suggested that she should steer away from her original pop style and gear her music toward jazz and ballads. In 1962, they collaborated, producing the album Nancy Wilson and Cannonball Adderley, which propelled her to national prominence with the hit R&B song, "Save Your Love For Me"; Wilson would later appear on Adderley's live album In Person (1968). Between March 1964 and June 1965, four of Wilson's albums hit the Top 10 on Billboard's Top LPs chart. In 1963, "Tell Me The Truth" became her first truly major hit, leading up to her performance at the Coconut Grove in 1964 – the turning point of her career, garnering critical acclaim from coast to coast. TIME said of her, "She is, all at once, both cool and sweet, both singer and storyteller." In 1964 Wilson released what became her most successful hit on the Billboard Hot 100 with "(You Don't Know) How Glad I Am", which peaked at No. 11. From 1963 to 1971 Wilson logged 11 songs on the Hot 100, including two Christmas singles. However, "Face It Girl, It's Over" was the only remaining non-Christmas song to crack the Top 40 for Wilson (No. 29, in 1968).

After making numerous television guest appearances, Wilson eventually got her own series on NBC, The Nancy Wilson Show (1967–1968), which won an Emmy. Over the years she appeared on many popular television shows from I Spy (more or less playing herself as a Las Vegas singer in the 1966 episode "Lori", and a similar character in the 1973 episode "The Confession" of The F.B.I.), Room 222, Hawaii Five-O, Police Story, The Jack Paar Program, The Sammy Davis Jr. Show (1966), The Danny Kaye Show, The Smothers Brothers Comedy Hour, Kraft Music Hall, The Sinbad Show, The Cosby Show, The Andy Williams Show, The Carol Burnett Show, Soul Food, New York Undercover, Moesha and The Parkers. She was a guest on numerous popular variety and talk shows including The Ed Sullivan Show, The Merv Griffin Show, The Tonight Show, The Arsenio Hall Show and The Flip Wilson Show. She was in the 1993 Robert Townsend's The Meteor Man and in the film, The Big Score. She also appeared on The Lou Rawls Parade of Stars and the March of Dimes Telethon.

She was signed by Capitol Records in the late 1970s and in an attempt to broaden her appeal she cut the album Life, Love and Harmony, an album of soulful, funky dance cuts that included the track "Sunshine", which was to become one of her most sought-after recordings (albeit among supporters of the rare soul scene with whom she would not usually register). In 1977 she recorded the theme song for The Last Dinosaur, a made-for-TV movie which opened in theaters in Japan.

In the 1980s, she recorded five albums for Japanese labels because she preferred recording live, and American labels frequently did not give her that option. She gained such wide popularity that she was selected as the winner of the annual Tokyo Song Festivals.