Otto Holzapfel (born February 5, 1941, in Beeskow) is a German folklorist and researcher of traditional German folk song (folk music, Lied).
He studied in Frankfurt am Main; among his subjects were Scandinavian languages and literature with Klaus von See.
Special topics of Holzapfel are the traditional German folk ballad and the tradition of the German folk song, European mythology and German-Danish genealogy.
He has edited several volumes of the standard edition of the traditional German folk ballads Deutsche Volkslieder mit ihren Melodien: Balladen (10 volumes, 1935–1996), and he created a system for analyzing German quatrains (Schnaderhüpfel, four line lyric stanzas, Gstanzl).
Since 2006 he supervises the German song index (Liedverzeichnis')', now online.