Gunnar Hansen Horn (25 June 1894 – 15 July 1946) was a Norwegian petroleum geologist and Arctic explorer. He is most renowned as the leader of the Bratvaag Expedition that found the long-lost remains of S. A. Andrée's Arctic balloon expedition of 1897 at Kvitøya in 1930. The headland Hornodden of Kvitøya is named after him.
Gunnar Hansen Horn was born in Kristiania (now Oslo), Norway. He was the son of architect Fin Horn (1861-1929) his wife and Kathinka Marie Hansen (1865-1942). Horn studied mining at the Norwegian Institute of Technology in Trondheim, graduating in 1916. He then studied petroleum geology at Royal School of Mines in London, and took a Ph.D. in coal petrography at the Berlin Technical University in Charlottenburg. 
He was a leading Norwegian authority on coal and petroleum geology in the interwar years. In 1917, Horn was employed as a mining engineer for Store Norske Spitsbergen Kulkompani on Spitsbergen. He worked from 1920 to 1923 as a petroleum geologist in Trinidad and Venezuela. In 1924 he became employed at the Norwegian Polar Institute. In addition to his purely scientific work, Horn also had administrative duties in the Arctic islands.
During 1930, he headed the scientific expedition on the sealing vessel M/S Bratvaag which sailed under captain Peder Eliassen. The expedition located the camp of Swedish Arctic scientist Salomon August Andrée on Kvitøya. Other expeditions went to East Greenland and Franz Josef Land.
- "Hornodden (Svalbard)". Norwegian Polar Institute. Retrieved 2 July 2013.
- "Salomon August Andrée". Store norske leksikon. Retrieved June 1, 2017.
- Henriksen, Petter, ed. (2007). "Gunnar Hansen Horn". Store norske leksikon (in Norwegian). Oslo: Kunnskapsforlaget. Retrieved 6 August 2009.
- "Gunnar Hansen Horn". lokalhistoriewiki.no. Retrieved June 1, 2017.
- "Fin Horn". lokalhistoriewiki.no. Retrieved June 1, 2017.
- Rolf Bryhn. "Store Norske Spitsbergen Kulkompani AS". Store norske leksikon. Retrieved June 1, 2017.
- "Peder Eliassen". Norsk Polar History. Retrieved June 1, 2017.
- "The End of The Voyage - The Bratvaag Find". National Science Foundation University of Kansas. Retrieved June 1, 2017.
- Susan Barr. "Kapp Linné". Store norske leksikon. Retrieved June 1, 2017.
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