Eufrosina Dvoichenko-Markov (1901–1980) was a Russian-American history and literary scholar identified by National Security Agency as agent Masha who worked for the New York NKGB Rezidentura from 1943 to 1945.
Demetrius Dvoichenko-Markov of the United States Army, is also identified by the Venona papers as a Soviet agent, but spent the rest of his life as an academician in the United States.
Masha provided Soviet intelligence with information on Romanians, Carpatho-Russians, and other exile groups in the United States.
Masha also provided information on United States Department of State personnel with whom she had contact.
She died in Moscow in 1980.