Johannes Hans Daniel Jensen (25 June 1907 – 11 February 1973) was a German nuclear physicist. During World War II, he worked on the German nuclear energy project, known as the Uranium Club, in which he made contributions to the separation of uranium isotopes. After the war Jensen was a professor at the University of Heidelberg. He was a visiting professor at the University of Wisconsin–Madison, the Institute for Advanced Study, Indiana University, and the California Institute of Technology.