Karl Wilhelm Diefenbach (1851-1913) was a German painter and social reformer.
Diefenbach is a champion of reform of life , as the pioneer of naturism and the peace movement. His commune "Himmelhof" in Ober St. Veit (1897-1899) was one of the models for the students of his Gusto Graser reform founded settlements Monte Verita in Ascona.
As a painter he is an independent representative of Art Nouveau and Symbolism.
Diefenbach was a son of the painter and art teacher at the high school Hadamar Leonhard Diefenbach.