Boris Evgenievich Kochno or Kokhno (Russian: Бори́с Евге́ньевич Кохно́; 3 January 1904, in Moscow – 8 December 1990, in Paris) was a Russian poet, dancer and librettist.
Kochno was close with Karol Szymanowski, who gave him as a gift a Russian translation of the chapter The Symposium from Efebos, the composer's unpublished novel. Szymanowski also dedicated four poems to him. In 1920 he became Sergei Diaghilev's secretary, librettist, and eventually main collaborator. They were also briefly lovers. Kochno wrote the libretto of Stravinsky's Mavra (1921), the Fâcheux (1924), La Chatte (1927) and of the ballet The Prodigal Son (1929). He also had an affair with Cole Porter in 1925, with whom he carried on a lengthy correspondence.
At the end of World War II, Kochno entered into collaboration with Roland Petit, with whom he founded the Ballets des Champs-Élysées. There are a number of published works by him. One, Diaghilev and the Ballets Russes, is a record of the Diaghilev era. The other, Christian Bérard, is a scrapbook of reminiscences about, and art of, his former lover and collaborator.
He was buried in the Père Lachaise cemetery in Paris, next to Wladimir Augenblick.