Kaikhosru Shapurji Sorabji (born Leon Dudley Sorabji; 14 August 1892 – 15 October 1988) was an English composer, music critic, pianist and writer whose music, written over a period of seventy years, ranges from sets of miniatures to works lasting several hours. One of the most prolific 20th-century composers, he is best known for his piano pieces, notably nocturnes such as Gulistān and Villa Tasca, and large-scale, technically intricate compositions, which include seven symphonies for piano solo, four toccatas, Sequentia cyclica and 100 Transcendental Studies. He felt alienated from English society by reason of his homosexuality and mixed ancestry, and had a lifelong tendency to seclusion.

Sorabji was educated privately. His mother was English and his father a Parsi businessman and industrialist from India, who set up a trust fund that freed his family from the need to work. Although Sorabji was a reluctant performer and not a virtuoso, he played some of his music publicly between 1920 and 1936. In the late 1930s, his attitude shifted and he imposed restrictions on performance of his works, which he lifted in 1976. His compositions received little exposure in those years and he remained in public view mainly through his writings, which include the books Around Music and Mi contra fa: The Immoralisings of a Machiavellian Musician. During this time, he also left London and eventually settled in the village of Corfe Castle, Dorset. Information on Sorabji's life, especially his later years, is scarce, with most of it coming from the letters he exchanged with his friends.

As a composer, Sorabji was largely self-taught. Although he was attracted to modernist aesthetics at first, he later dismissed much of the established and contemporary repertoire. He drew on such diverse influences as Ferruccio Busoni, Claude Debussy and Karol Szymanowski and developed a style blending baroque forms with frequent polyrhythms, interplay of tonal and atonal elements and lavish ornamentation. Though he composed mostly for the piano and has been likened to the composer-pianists he admired, including Franz Liszt and Charles-Valentin Alkan, he also wrote orchestral, chamber and organ pieces. His harmonic language and complex rhythms anticipated works from the mid-20th century onwards, and while his music remained largely unpublished until the early 2000s, interest in it has grown since then.