Jens Peter Jacobsen (7 April 1847 - 30 April 1885) was a Danish novelist , poet , and scientist. He began the naturalist movement in Danish literature.

Jacobsen was born in Thisted in Jutland. He was the eldest of the five children of a prosperous merchant. Jacobsen went to school in Copenhagen and later became a student at the university of Copenhagen in 1868. As a boy, he showed a remarkable talent for science, particularly for botany. In 1870, although he was secretly writing verses already, Jacobsen adopted botany as a profession. He was sent by a scientific body in Copenhagen to report on the flora of the islands of Anholt and Land. About this time the discoveries of Charles Darwin began to exercise a fascination over him, and finding them little understood in Denmark, he translated into Danish The Origin of Species and The Descent of Man.