Alfred Gabriel Nathorst (born November 7, 1850 in Väderbrunn outside Nyköping – died January 20, 1921 in ) was a Swedish Arctic explorer, geologist and palaeobotanist.
Nathorst’s interest in geology was awoken by Charles Lyell’s ‘’Principles of Geology‘’ and, at the age of 21, Nathorst visited Lyell in England in 1872.
Nathorst was employed at the Geological Survey of Sweden in 1873-84. He was then appointed professor, by royal decree on the 5 December 1884, and was simultaneously made curator of the new “Department of Archegoniates and Fossil Plants" at the Swedish Museum of Natural History. He remained on the post until his retirement in 1917.
Nathorst visited Spitsbergen in 1870 and participated in 1882-83 in the 2nd Dickson Expedition ("Den andra Dicksonska Expeditionen till Grönland") led by Adolf Erik Nordenskiöld. He led an expedition on the ship Antarctic to Bear Island and Svalbard including the isolated Kong Karls Land in 1898. The following year (1899), Nathorst led an expedition to Greenland. This second expedition had as the dual purpose of geographical mapping and of searching for survivors of S. A. Andrée's Arctic balloon expedition of 1897. The Andreé expedition was not found, however. The two expeditions are described in two volumes "Två somrar i Norra Ishavet" (in Swedish).