Isolde Beidler (born Isolde von Bülow: 10 April 1865 – 7 February 1919) was the third of the five stepchildren and children of the composer Richard Wagner and his wife, who is generally known as Cosima Wagner (though the two of them married only in 1870).
Isolde herself married the Swiss-born conductor Franz Beidler (1872-1930) and was the mother of author Franz Wilhelm Beidler (1901-1981), celebrated at his birth as "Richard Wagner's first grandchild".In view of the enduring interest in Richard Wagner's antisemitic opinions, it becomes intriguing that in 1923 Isolde Beidler posthumously acquired a Jewish daughter-in-law.