Barbara Cook

Are you kidding? Am I really the first to describe this legend? Here, from:
Wikipedia,
Barbara Cook (b. October 25, 1927 in Atlanta, Georgia) is an American singer and actress, famed for creating roles in the musicals Candide and The Music Man, among many others.
Cook made her Broadway debut in 1951 as Sandy in the short-lived musical Flahooley. She next took roles in revivals of two Rodgers and Hammerstein hits: Ado Annie in Oklahoma! and Carrie Pipperidge in Carousel. In 1955, she began to attract major critical praise when she played the supporting role of Hilda Miller in Plain and Fancy, a modest hit.
Cook's good reviews and clear soprano voice enabled her to win the role of Cunegonde in Leonard Bernstein's new musical, Candide in 1956. In this show, she sang "Glitter and Be Gay".
Although Candide was not a success, Cook's portrayal of Cunegonde established her as one of Broadway's leading ingenues. Her two most famous roles after this were Marian the Librarian in Meredith Willson's 1957 hit The Music Man and as Amalia Balash in Jerry Bock and Sheldon Harnick's 1962 show She Loves Me. The song "Ice Cream", from the latter musical, later became one of Cook's signature songs.
During the 1960s, Cook also created roles in some less successful musicals: Liesl Brandel in 1961's The Gay Life and Carol Deems in 1964's Something More! She also tried her hand at non-musical roles, replacing Sandy Dennis in the play Any Wednesday and originating the role of Patsy Newquist in Jules Feiffer's Little Murders.
Cook's last original musical role on Broadway came in 1971 when she played Dolly Talbo in The Grass Harp. But she did not abandon the stage. She has since become a successful concert performer, creating critically-acclaimed solo shows such as Mostly Sondheim and Barbara Cook's Broadway. She originated the role of Margaret White in the notorious musical version of Stephen King's Carrie when it premiered in England.
On March 9, 1952, she married David LeGrant, an acting teacher; they had one son.