Girolamo Alessandro Frescobaldi (Italian: [dʒiˈrɔːlamo freskoˈbaldi]; also Gerolamo, Girolimo, and Geronimo Alissandro; September 1583 – 1 March 1643) was an Italian composer and virtuoso keyboard player. Born in the Duchy of Ferrara, he was one of the most important composers of keyboard music in the late Renaissance and early Baroque periods. A child prodigy, Frescobaldi studied under Luzzasco Luzzaschi in Ferrara, but was influenced by many composers, including Ascanio Mayone, Giovanni Maria Trabaci, and Claudio Merulo. Girolamo Frescobaldi was appointed organist of St. Peter's Basilica, a focal point of power for the Cappella Giulia (a musical organisation), from 21 July 1608 until 1628 and again from 1634 until his death.

Frescobaldi's printed collections contain some of the most influential music of the 17th century. His work influenced Johann Jakob Froberger, Johann Sebastian Bach, Henry Purcell, and other major composers. Pieces from his celebrated collection of liturgical organ music, Fiori musicali (1635), were used as models of strict counterpoint as late as the 19th century.