Hans-Günter Klein (24 November 1939 in Berlin – 7 April 2016 idem) was a German musicologist, librarian, art historian, LGBT activist and researcher on the Mendelssohn family.
After that he grew up in Hamburg, where he studied musicology, philosophy and history of art.
He immediately moved to Berlin to the music department of the Staatsbibliothek zu Berlin, whose Mendelssohn Archive he joined after Rudolf Elvers left the library (1988) and headed it for fifteen years (until 2003).
Klein was heavily involved in research on musicians who were persecuted or ostracized during the National Socialist era, including Viktor Ullmann and Gideon Klein.
Klein died in Berlin at the age of 76 and found his final resting place at Friedhof I der Dreifaltigkeitsgemeinde, Mehringdamm 21 in Berlin-Kreuzberg.