Karl Reinhold "Kai" Donner (1 April 188812 February 1935) was a Finland Swede linguist, ethnographer and political activist. He carried out expeditions to the Samoyedic and Ket peoples in Siberia between 1911 and 1914, and was docent of Uralic languages at the University of Helsinki from 1924. A central figure in Finland's independence movement, he was active in the Jäger movement and later became a prominent leader of the Lapua movement. He is also known for writing the first authoritative biography of Mannerheim.
left|thumb|Kai Donner in his malitsa on the tundra, 1913.
Studying the Finno-Ugric-speaking peoples of Siberia had become an important part of the "national sciences" that arose in answer to the interest in national "roots" following the "National Awakening" of the mid-19th century. Donner decided early on to follow in the footsteps of pioneer philologist and explorer M. A. Castrén (1813–1852). On his first trip he travelled along the upper reaches of the Ob and most of the Yenisey between 1911 and 1913. His second trip took him to the Ob, Irtysh, and upper Yenisei. Living with the Nenets and Khanty people, Donner studied not only the language but also the way of life and beliefs of his hosts. Conditions on the expeditions were extreme: winter temperatures sometimes fell below −50 °C, and Donner was at times forced to eat carrion to avoid starvation. In the summer of 1912 he fell seriously ill with a fever; a well-stocked medical kit saved his life. The prolonged hardships of the expeditions took a severe toll on his health and were likely the primary cause of his early death at the age of 46.
Works
- Bland samojeder i Sibirien åren 1911–1913, 1914 (1915)
- Itsenäisyytemme. Aktivistisia puheita ja kirjoituksia (1919)
- Sibiriska noveller (1919)
- Über die anlautenden labialen spiranten und verschlusslaute im samojedischen und uralischen (1920), his academic dissertation.
- Ethnological notes about the Yenisey-Ostyjak (in the Turukhansk region) (1933)
- Sibirien. Folk och forntid (1933) — considered his most significant scientific work of lasting value.