John Field (July 26, 1782 - January 23, 1837) was an Irish composer and pianist. He is best known for being the first composer to write nocturnes.
Born in Dublin, Field first studied the piano under his father, who was a violinist, and later under Tommaso Giordani. He later went went to London where he studied under Muzio Clementi. He toured Europe both to demonstrate the pianos that Clementi made and as a concert pianist before settling in St Petersburg in Russia where he was a popular performer and teacher. He died in Moscow.
Field is best remembered as the first composer to write nocturnes, single movement pieces for piano which were not in a fixed form (as the minuet or fugue are) and which maintained a single mood throughout. These pieces greatly influenced Frederic Chopin, who went on to write 21 nocturnes himself. Inasmuch as Field's nocturnes were the first single-movement piano character pieces, they can be seen as important forerunners of many other Romantic composers' works, among them Felix Mendelssohn, Robert Schumann, Franz Liszt and Edvard Grieg.
Field also wrote seven piano concertos of which the best known is probably the second (1811).