Heinrich Lemacher (26 June 1891 – 16 March 1966) was a German composer and music educator.
Born in Solingen, Lemacher studied from 1911 to 1916 at the Cologne Conservatory and at Bonn University, where he received his doctorate in musicology in 1916.
From 1925 to 1965 he taught composition, theory and music history at the Hochschule für Musik Köln, where he had been professor since 1928.
Important students of Heinrich Lemacher were Heinrich Weber, Bernd Alois Zimmermann, and his long-time colleague at the Cologne Academy of Music Hermann Schroeder, who was also co-author of his most important teaching works.
He was widowed by Maria Augusta Horst, whom he had married in Cologne in 1927.