Born in Bayreuth, Germany, in 1942, Wagner was the daughter of Wieland Wagner, who with his brother Wolfgang led the Bayreuth Festival, devoted to Wagner's works, after World War Two.
A painter, photographer, filmmaker and translator, Wagner sat on the board of trustees of the Richard Wagner Foundation, which was formed in 1973 to oversee the estate of the composer.
She mostly stayed in the background of the family squabbles that the Wagner clan is famous for, but in recent years she criticized the foundation for its decision-making process.
She opposed plans to expand the Richard Wagner Museum, threatening to take legal action against it, which sits in the Wahnfried House, and media reports at the time said she blocked plans for a cafe and gift shop near the composer's grave.
Iris Wagner is survived by her three siblings Wolf Siegfried, Daphne and Nike Wagner, who is assuming leadership of the Beethovenfest Bonn beginning in the 2014 season.