Max Koecher (* 20 January 1924 in Weimar; † 7 February 1990 in Lengerich) was a German mathematician.
Koecher studied mathematics and physics at the Georg-August-Universität in Göttingen. In 1951 he received his doctorate under Max Deuring with his work (Koecher 1953) on Dirichlet series with functional equation where he introduced Koecher–Maass series. He qualified in 1954 at the Westfälische Wilhelms University in Münster. From 1962 to 1970 Koecher was department chair at the University of Munich. He retired in 1989.
His main research area was the theory of Jordan algebras, where he introduced the Kantor–Koecher–Tits construction. He discovered the Koecher boundedness principle in the theory of Siegel modular forms.