Fannia Mary Cohn (April 5, 1885 – December 24, 1962) was a leading figure in the International Ladies' Garment Workers' Union (ILGWU) during the first half of the 20th century.

Fannia Mary Cohn was born on April 5, 1885, to an ethnic Jewish family in Kletsk, Belarus, then part of the Russian Empire.

[1] Cohn decided against further formal education in 1905, instead taking a job as a garment worker in order to participate directly in the Yiddish-language labor movement of New York City.

[3] During the years 1912 and 1913 Cohn played a prominent role as a leader of the strike movement of New York City's organized garment workers.

[2] In 1915, she was asked by the International Ladies' Garment Workers' Union to organize Chicago dressmakers and in doing so founded ILGWU Local No.

[7] In connection with this activity, Cohn was a key leader of a major strike of Chicago garment workers which began late in 1915 and continued into the following year, serving as a general organizer for the ILGWU.

After being elected as the first female vice president of ILGWU, Fannia Cohn continued to pioneer and promote an image of the labor movement that integrated education as well as personal growth.

[2] As a result, Fannia Cohn would be blamed for this rebellion as well as her failure to condemn it and would thus be castigated and ostracized from all fronts – including the militants she inspired.

[10] Despite the failure of that organization to survive beyond 1925, Cohn remained active in left wing politics at least through the 1940s as a member of the League for Industrial Democracy.