Anna von Mildenburg (November 29, 1872 – January 27, 1947) was an eminent Wagnerian soprano of Austrian nationality. Known as Anna Bahr-Mildenburg after her 1909 marriage, she had been a protégé of the composer/conductor Gustav Mahler during his musical directorship at the Hamburg State Opera. In 1898, Mahler took her to the Vienna Opera, where she established herself as one of the great stars during his celebrated tenure there as music director.
Anna Bellschan von Mildenburg, to give her full maiden name, was born in Vienna, the Austrian capital. She studied voice with Rosa Papier and Johannes Ress at the Conservatory of Gesellschaft der Musikfreunde in Vienna, and then privately with Cosima Wagner and Mahler. She had an affair with the latter which lasted until 1897.
Von Mildenburg made her operatic debut in 1895 at Hamburg, singing the role of Brünnhilde in The Ring Cycle under Mahler's baton. Then, in 1897, she performed the role of Kundry in Parsifal at the Bayreuth Festival, and also took on the mezzo-soprano part of Ortrud in Tannhäuser. Cosima Wagner, the composer's widow, became her mentor at Bayreuth, and she proceeded to perform all the main Wagnerian soprano parts at the festival prior to the outbreak of World War I in 1914.
She first sang at the Vienna Hofoper on 8 December 1897, when she took the role of Brünnhilde in Die Walküre under Hans Richter. Mahler put her on a contract and she soon experienced enormous success. In her first season alone she earned 14,000 gulden (about €112,000 in 2008). Her stature at the opera house equaled that of Mahler, who was then the establishment's director of music. She would perform at the Vienna State Opera until 1917, and then again in 1919-1920. Among her most celebrated performances during this period was an assumption of Isolde's role in a famous production of Tristan und Isolde mounted under Mahler's leadership.