Enzio Rafael Reuter (30 March 1867, in Turku – 11 February 1951, in Helsinki) was a Finnish entomologist who specialised in Lepidoptera. He wrote Über die Palpen der Rhopalocera: Ein Beitrag zur Erkenntnis der verwandtschaftlichen Beziehungen unter den Tagfaltern, an important work on the classification of lepidoptera in which some higher level taxa are erected. Reuter was a cytologist and student of phylogenetics. His collection is conserved in the Natural History Museum of Helsinki. Reuter was a correspondent with and admirer of the German Darwinist Ernst Haeckel: