Johann Christoph Demantius (15 December 1567 – 20 April 1643) was a German composer, music theorist, writer and poet.
He was an exact contemporary of Monteverdi, and represented a transitional phase in German Lutheran music from the polyphonic Renaissance style to the early Baroque.
In 1594 he moved to Leipzig, and in 1597 he acquired the post of Kantor at Zittau, where he probably taught the young Melchior Franck.
They are conservative in that they avoid some of the Italian Baroque innovations such as the concertato style and the basso continuo, both of which were becoming widely used in Germany by 1610; but he also created a highly individual musical language using traditional forms and means, quite distinct from the Palestrinian polyphony adopted by the other composers of the time commonly regarded as "conservative."
He also wrote secular music, both vocal and instrumental, including threnodies, dances, epithalamia, and numerous other occasional works.