Nicolai Alexandrovich Vasiliev (Russian: Николай Александрович Васильев), also Vasil'ev, Vassilieff, Wassilieff (11 July [O.S. 29 June] 1880 – December 31, 1940), was a Russian logician, philosopher, psychologist, poet. He was a forerunner of paraconsistent and multi-valued logics.