Fernando Sor (baptized 14 February 1778 – 10 July 1839) was a Spanish classical guitarist and composer. Although he is best known for his guitar compositions, he also composed music for a wide range of genres, including opera, orchestra, string quartet, piano, voice, and ballet. His ballet score Cendrillon (Cinderella) received over one hundred performances. Sor's works for guitar range from pieces for beginning players to advanced players such as Variations on a Theme of Mozart. Sor's contemporaries considered him to be the best guitarist in the world, and his works for guitar have been widely played and reprinted since his death. Unlike modern classical guitar players, Sor rarely used the ring finger of his plucking hand, and eschewed the use of nails on the plucking hand.

As Sor's works were published in various countries, his name was translated, leading to variations in the spelling. Variations have included Fernando Sor, Joseph Fernando Macario Sors, Ferdinand Sor, and Ferdinando Sor and, in the last years, Ferran Sor, even though there is no record of him using that name.

Likewise, the surname of the guitarist and composer appears in different forms in contemporary documents. In the file and marriage certificate of his grandfather, which also includes the great-grandfathers of Fernando, the surname always appears as Sor, as well as that of his great-grandfather, the oldest document found to date.