As her obituary in The New York Times summed it up, Diener's "lush beauty, showstopping stage presence and operatic voice made her a favorite in musicals, especially in the original 1965 Man of La Mancha.

[2][3] She made her Broadway debut in the 1948 revue Small Wonder, directed by Burt Shevelove and choreographed by Gower Champion and co-starring Tom Ewell, Alice Pearce and Jack Cassidy.

[6] Times theater critic Brooks Atkinson wrote, "As an abandoned hussy, brazenly made up and loosely clad, Joan Diener looks like a fine case of grand arson and warms up the whole show.

Mitch Leigh's Man of La Mancha also was directed by Marre, who cast his wife as Aldonza, the lusty serving wench envisioned by the deranged Don Quixote as virtuous Dulcinea.

At age 62, she took over the same role she had created decades earlier in the 1992 Broadway revival starring Raúl Juliá when Sheena Easton collapsed during one performance and Diener filled in for the second half of the show.