Gré Brouwenstijn (born Gerda Demphina: 26 August 1915 in Den Helder – 14 December 1999 in Amsterdam) was a Dutch soprano singer whose stage career spanned from the early 1940s to the mid-1970s.
She studied voice at the Amsterdam Muzieklyceum, with Jaap Stroomenbergh, Boris Pelsky and Ruth Horna. She made her operatic début in 1940 as the First Lady in The Magic Flute. Brouwenstijn then became a member of the Hilversum Radio Choir, later performing as a soloist in operatic broadcasts. In 1946, she joined the Netherlands Opera, where she made her debut as Giulietta in Les contes d'Hoffmann.
In 1949, Brouwenstijn made her debut at the Holland Festival as Leonora in Il Trovatore, the beginning of a long association. In subsequent years, she sang Reiza (Oberon), Jenůfa, Amelia, Donna Anna, Desdemona, the Countess, Tatyana, Leonora (La forza del destino), Senta, Iphigénie (Iphigénie en Tauride), and Leonore (Fidelio) at the Festival.
Brouwenstijn was above all associated with the role of Leonore in Beethoven's Fidelio. Considered one of the finest Leonores of her time, she performed the role to great acclaim at the Vienna State Opera, the Paris Opera, Stuttgart, Berlin, Amsterdam, Buenos Aires, London, and Glyndebourne.
In 1951, Brouwenstijn made her debut at the Royal Opera House, Covent Garden as Aida (in English), conducted by Sir John Barbirolli. Her Berlin debut in 1954 caused "something of a sensation"; the critic praised her "phrasing in Italian opera". In 1955, under Rafael Kubelík, she sang Desdemona. In 1958, she sang Elisabetta in a famous production of Don Carlos designed by Luchino Visconti and conducted by Carlo Maria Giulini. In 1958 she sang Leonore at the Teatro Colón in a production of Fidelio conducted by Thomas Beecham.