John Field (26 July 1782 – 23 January 1837) was an Irish pianist, composer and teacher widely credited as the inventor of the nocturne. While many of his contemporaries wrote in a similar style, Field was the first to use the term to apply to a character piece featuring a cantabile melody over an arpeggiated accompaniment.

Born into a musical family in Dublin, he received his early education in the city, particularly with Tommaso Giordani. The family moved to London in 1793 where, under the tutelage of Muzio Clementi, Field soon became a famous and sought-after concert pianist. Together, they visited Paris, Vienna, and Saint Petersburg. Ambiguity surrounds Field's decision to remain in the latter, but it is likely that Field acted as a sales representative for Clementi & Co..

Field was very highly regarded by his contemporaries and his playing and compositions influenced many major composers, including Felix Mendelssohn, Frédéric Chopin, Johannes Brahms, Robert Schumann, and Franz Liszt. Although little is known of Field's time in Russia, he undoubtedly contributed substantially to concerts and teaching, and to the development of the Russian piano school.

Amongst his students were Charles Mayer, Alexandre Dubuque, and Antoine de Kontski.