Marxist n.

1886, "a devotee of the teachings of German political theorist Karl Marx" (1818-1883), from French marxiste. The adjective, "of or pertaining to the socialist doctrines and theories of Karl Marx," is attested from 1884. The alternative adjectival form Marxian (1887 in reference to Karl Marx) sometimes is used (1940, by Groucho, among others) to distinguish the U.S. vaudeville family from the German political theorist.