Jan Pieterszoon Sweelinck (Swelinck, Zwelinck, Sweeling, Sweelingh, Sweling, Swelingh) was a Dutch composer, organist, and pedagogue whose work straddled the end of the Renaissance and beginning of the Baroque eras.

Many of Jan Pieterszoon Sweelinck's family were musicians - principally organists. He was the elder son of Peter Swybbertszdon and Elske Sweeling, he adopted his mother's family name. The assertion that he studied in Venice with Zarlino, the famous composer and theorist, is not supported by surviving evidence. His only known teachers besides his father were Jacob Buyck, pastor at the Oude Kerk, Amsterdam, and Jan Willemszoon Lossy, a counter-tenor and shawm player at Haarlem, who taught him not organ but composition. By 1580, and possibly as early as 1577, he was organist at the Oude Kerk; his duties there were probably to provide an hour of music twice daily in the church. He became famous for his brilliant improvisations at the organ and harpsichord. From this time onward he left Amsterdam only to inspect new organs and advise on repairs and restorations.

As a teacher Jan Pieterszoon Sweelinck was influential and sought after, and his pupils were among the most highly regarded musicians of the time; they included Andreas Duben, Peter Hasse, Samuel Scheidt and Gottfried Scheidt, Paul Siefert, Ulrich Cernitz, Jacob Praetorius, and Johann Heinrich Scheidemann, founders of the so-called north German organ school of the 17th entury. He was known in Germany as the "maker of organists".