Mark Gayn (né Mark Julius Ginsbourg; 21 April 1909–17 December 1981) was an American and Canadian journalist, who worked for The Toronto Star for 30 years.
Mark Julius Ginsbourg was born in 1909 in Barim, Manchuria, in the Qing Empire (today Balin [巴林鎮], Yakeshi in Inner Mongolia, China) to Russian-Jewish parents who had migrated from the Russian Empire. He went to school in Vladivostok in the Soviet Union and then in Shanghai, China. He was accepted to Pomona College in Claremont, California, in the United States where he majored in political science. Following his graduation from Pomona, he entered the School of Journalism at Columbia University, graduating in 1934.
Ginsbourg got into his career in the 1930s as a stringer (journalism) for Washington Post in the Shanghai. He returned to the U.S. shortly after World War II broke out in Europe, changing his name to Gayn to prevent Japanese reprisals against his brother Sam, who remained in Japanese-occupied Shanghai. Gayn also went on to write for Collier's and was arrested in the FBI raid on the offices of the Institute for Pacific Relations' Amerasia office in June 1945.