Franz Tunder (1614 – 1667) was a German composer and organist of the early to middle Baroque era.
He was an important link between the early German Baroque style which was based on Venetian models, and the later Baroque style which culminated in the music of J.S. Bach; in addition he was formative in the development of the chorale cantata.
Between 1632 and 1641, Tunder worked in Gottorf as "Hoforganist".
In 1641 he was appointed as the main organist at Lübeck's main church, the Marienkirche, succeeding Peter Hasse.
In 1647 he became administrator and treasurer there also. He held that post for the rest of his life.
His successor was Dieterich Buxtehude. Buxtehude married Tunder's daughter, Anna Margarethe, in 1668.
He began the tradition of "Abendmusiken", a long series of free concerts in the Marienkirche, the most elaborate of which were before Christmas time. The earliest of these concerts occurred in 1646. The concerts seem to have originated as organ performances specifically for the businessmen who congregated at the weekly opening of the town's stock exchange.
These concerts were to continue through the 17th and 18th centuries; they were distinguished from other concerts by having free admission (for they took place in a church), and by being financed by the business community.
Along with Heinrich Scheidemann and Matthias Weckmann, Tunder was one of the most important members of the North German organ school; however, few of his works are preserved.