Oiva Johannes Tuulio (17 January 1878, Pyhäjärvi – 21 June 1941, Helsinki) was a Finnish linguist specializing in the Romance languages.
[1] Tuulio was son to provost Ivar Markus Tallgren and Jenny Maria Montin.
[2] He earned his PhD in 1907, was awarded the title of docent in 1910 and served as extraordinary professor of the Southern Romance languages at the University of Helsinki from 1928 to 1941.
[4] Tuulio pioneered the field of Spanish research in Finland; his PhD thesis, Estudios sobre la Gaya de Segovia (1907), was the first study about Spanish written in that language at the University of Helsinki.
Together with his brother, archaeologist Aarne Michaël Tallgren, he published Idrisi, la Finlande et les autres pays baltiques orientaux (1930), in which he attempted to show similarities between place names on the maps by Muhammad al-Idrisi and place names in Finland and the Baltics.