Emil Frey-Gessner (19 March 1826, in Aarau – 24 July 1917, in Genf) was a Swiss entomologist. At first Emil Frey-Gessner studied mechanical engineering and was until 1865 technical director in the Frey-Gessner family cotton mill. Later he studied natural sciences at the Eidgenössische Technische Hochschule Zürich and became a District Teacher in Brugg then in the Canton of Aarau. From 1872 he was conservator of the entomological collections at the new museum of Geneva University. He was Dr. hc of the University of Geneva.[1][2]