Frank Duffy (6 May 1861 – 11 July 1955) was an American labor leader and secretary-general of the United Brotherhood of Carpenters and Joiners of America from 1901 to 1950.
When the New York City local formed a district council, Duffy was elected its first president.
After the United Order merged with the United Brotherhood of Carpenters and Joiners of America in 1888, Duffy was elected to a number of posts in the new Local 478 in New York City.
He played a key role in ousting long-time Carpenters president Peter J. McGuire in 1901.
In 1919, Duffy served as one of several American labor representatives to the Paris Peace Conference in 1919.