Walter Gerhard Martin Sommer (8 February 1915 – 7 June 1988) was an SS Hauptscharführer (master sergeant) who served as a guard at the concentration camps of Dachau and Buchenwald. Sommer, known as the "Hangman of Buchenwald" was considered a depraved sadist who reportedly ordered two Austrian priests, Otto Neururer[1] and Mathias Spannlang[2], to be crucified upside-down.[3][4]