Ivar Fredrik Lassy (18 November 1889 – 4 June 1938) was a Finnish writer and anthropologist who was active in the Socialist and Communist parties.

In his research, Lassy studied the Turkic people of Caucasus and later the history of sexual ethics, although he was expelled from the academic circles for joining the Reds in the 1918 Civil War of Finland.

In 1909, Lassy entered the University of Helsinki where he studied aesthetics, philosophy, literature and economics earning his 1916 doctorate in Azerbaijanis folk tradition.

[3][4] As the Civil War broke out in January 1918, Lassy offered his services for the Peoples Delegation and was hired as a translator by Yrjö Sirola.

According to Lassy, he joined the Reds because he saw the worker's revolution as a subject on anthropological research, but was soon sucked into the aspect as he learned to understand their demands.

He worked as a translator at the Komintern publishing company and the director of the Scandinavian section of the Communist University of the National Minorities of the West.

[3][4] Lassy's literal works include the 1931 Finnish book Marxismin perusteet (Foundations of Marxism) which was later declared as contrarevolutionary.