Manfred Trojahn (born 22 October 1949) is a German composer, flutist, conductor, writer and academic teacher.
After graduating in 1970 he concluded his studies as a flutist at the Hochschule für Musik und Theater Hamburg with Karlheinz Zöller.
Since 1991 he is professor for musical composition at the Robert Schumann Hochschule in Düsseldorf.
From 2004 until 2006 he was President of the Deutscher Komponistenverband [de]; from 2008 to 2012 he was vice-director of the music section of the Academy of Arts, Berlin.
Among Trojahn's students in composition are Oscar van Dillen, Matthias Pintscher and Daniel Hensel.