Josef Seger (born Josef Ferdinand Norbert Segert, last name also Seeger or Seegr) (1716–1782) was a Czech organist, composer, and educator. After graduating in philosophy from the Charles University in Prague and studying music under Bohuslav Matěj Černohorský, Jan Zach, and others, Seger became organist at two churches in Prague and remained there until his death.
In 1781, Emperor Joseph II was sufficiently impressed with Seger's playing and offered the composer a court appointment, but Seger died in Prague in 1782 before the confirming document arrived.
An extremely prolific composer, Seger became one of the most important representatives of the Czech organ school of the 18th century. None of Seger's compositions was published during his lifetime, but he was an important teacher and educator. His pupils included Karel Blažej Kopřiva, Jan Antonín Koželuh, Jan Křtitel Kuchař, Josef Mysliveček, and many other distinguished Bohemian composers and musicians. Seger was the most prolific Czech organ composer of the 18th century. Hundreds of preludes, fugues, toccatas and other organ pieces survive in manuscript copies, although the attribution to Seger of some of these works is problematic. His preludes and fugues are short works (their length probably dictated by the limitations imposed by the Catholic liturgy), but they exhibit a fertile harmonic imagination and a perfect grasp of late Baroque counterpoint practice. He also composed masses, motets and psalm settings; all also dominated by archaic counterpoint.