Francesca Gaetana Cosima Wagner (; 24 December 1837 – 1April 1930) was a German businesswoman who was the daughter of the Hungarian composer and pianist Franz Liszt and Franco-German romantic author Marie d'Agoult. She became the second wife of the German composer Richard Wagner, and with him founded the Bayreuth Festival as a showcase for his stage works. After his death she devoted the rest of her life to the promotion of the festival and his music and philosophy. Commentators have recognised Cosima as the principal inspiration for Wagner's later works, particularly Parsifal.
In 1857, after a childhood largely spent under the care of her grandmother and with governesses, Cosima married the conductor Hans von Bülow. Although the marriage produced two children, it was largely a loveless union, and in 1863 Cosima began a relationship with Wagner, who was 24 years her senior. They married in 1870; after Wagner's death in 1883 she directed the Bayreuth Festival for more than 20 years, increasing its repertoire to form the Bayreuth canon of ten operas and establishing the festival as a major event in the world of musical theatre.
During her directorship, Cosima opposed theatrical innovations and adhered closely to Wagner's original productions of his works, an approach continued by her successors long after her retirement in 1907. Under her influence, Bayreuth became increasingly identified with antisemitism. This was a defining aspect of Bayreuth for decades, into the Nazi era which closely followed her death there in 1930. Thus, although she is widely perceived as the saviour of the festival, her legacy remains controversial.
Family background and early childhood
thumb|upright|Franz Liszt, depicted at the time of his affair with Marie d'Agoult
In January 1833 the 21-year-old Hungarian composer and pianist Franz Liszt met Marie d'Agoult, a Parisian socialite six years his senior. Marie had been married since 1827 to Charles, Comte d'Agoult, and had borne him two daughters, but the union had become sterile. Drawn together by their mutual intellectual interests, Marie and Liszt embarked on a passionate relationship. In March 1835 the couple fled Paris for Switzerland; ignoring the scandal they left in their wake, they settled in Geneva where, on 18 December, Marie gave birth to a daughter, Blandine-Rachel. At the end, critical reactions ranged between that of the Norwegian composer Edvard Grieg, who thought the entire work "divinely composed", and that of the French newspaper Le Figaro who called the music "the dream of a lunatic". Wagner himself was far from satisfied; in a letter to Ludwig he denounced the singers Albert Niemann and Franz Betz as "theatrical parasites" and complained that Richter had not got a single tempo correct. Months later, Cosima records, his attitude towards the productions was "Never again, never again!".
Parsifal
After the conclusion of the festival and the departure of the guests, Wagner and Cosima left with the children for Venice, where they remained until December. The festival had accumulated a large financial deficit; this, and Wagner's deep artistic dissatisfaction, precluded the possibility of any repeat in the near future. Wagner's mood was such that he seriously contemplated giving up the entire Bayreuth project; he was distracted from such thoughts by an invitation to conduct a series of concerts in London. Leaving the children behind, he and Cosima enjoyed a two-month break in England where, among others, Cosima met the novelist George Eliot, the poet Robert Browning, and the painter Edward Burne-Jones (who made a number of sketches of Cosima from which no finished painting emerged). On 17 May both Wagners were received by Queen Victoria at Windsor Castle.