Kirsten Flagstad (July 12, 1895 – December 7, 1962) was a Norwegian opera singer born at Hamar.

She was an eminent Wagnerian soprano noted for her performances in Tristan and Isolde, especially under the conductor Wilhelm Furtwängler. She came to international repute when she performed at the Metropolitan Opera, New York in 1935 as Sieglinde in Wagner's Die Walküre.

She later became the first director of the National Opera in Norway.