Gunnar Landtman (6 May 1878, Helsinki – 30 October 1940, Helsinki) was a Finnish philosopher as well as a sociology and philosophy professor. A pupil of Edvard Westermarck, he graduated from the University of Helsinki in 1905. He later became an associate professor there from 1910 to 1927 and then a temporary professor until his death in 1940. Landtman was the first modern sociological anthropologist. His most important journey was a two-year trip to Papua New Guinea where he lived with the Kiwai Papuans from 1910 to 1912. He was from 1922 to 1924 a member of the Parliament of Finland, where he represented the Swedish People's Party of Finland (SFP).