Fernando Sor (baptized 14 February 1778 – 10 July 1839) was a prominent Spanish classical guitarist and composer of the late Classical and early Romantic eras. Born in Barcelona, Sor initially intended to follow a military career, a tradition in his family, but was captivated by music after being introduced to Italian opera and the guitar by his father. He received his initial musical education as a chorister at the monastery of Montserrat, where he developed skills in church music, composition, and orchestral playing.

Sor was renowned for his contributions to guitar music, composing not only for the guitar but also for voice, piano, and orchestra. His works include an opera composed at the age of 19, three symphonies, guitar duos, piano music, songs, a Mass, and successful ballets such as "Cinderella" and "Hercule et Omphale." His guitar compositions, particularly his didactic music such as the Twelve Studies Op. 6 and the Progressive Lessons Op. 31, have been celebrated for their pedagogical value and remain widely played.

Sor's career took him beyond Spain; after a brief stay in Paris in 1813, he settled in London, where he published many of his works, including the famous "Variations on a Theme of Mozart." He later traveled to Moscow before spending the remainder of his life in Paris, where he became a respected guitar teacher and continued to compose.

Despite his fame as a guitarist, Sor's use of the instrument was distinct from modern practices; he preferred the smaller "Romantic" guitars and rarely used the ring finger of his plucking hand. His name appeared in various forms across different countries, reflecting the international reach of his work. Sor passed away in Paris at the age of 61, leaving a lasting legacy as one of the foremost figures in the history of classical guitar music.