Ivar Giæver (Norwegian: [ˈìːvɑr ˈjèːvər]; anglicized as Giaever; born April 5, 1929) is a Norwegian-American physicist who shared the 1973 Nobel Prize in Physics with Leo Esaki and Brian Josephson. One half of the prize was awarded jointly to Giaever and Esaki "for their experimental discoveries regarding tunneling phenomena in semiconductors and superconductors, respectively".
In 1975, he was elected as a member into the National Academy of Engineering for contributions in the discovery and elaboration of electron tunneling into superconductors.
Giaever is a professor emeritus at the Rensselaer Polytechnic Institute and the president of the company Applied Biophysics.