Edward Joseph Gainor (August 1, 1870 – November 10, 1947) was an American labor unionist.

Born in Greencastle, Indiana, Gainor moved to Muncie, Indiana, working as a puddler and heater in a rolling mill. He joined the Amalgamated Association of Iron and Steel Workers, and served as secretary of his local from 1890 to 1892.

In 1897, Gainor left the mill, and became a letter carrier. He soon joined the National Association of Letter Carriers, and was elected to its executive in 1901. He became vice-president of the union in 1905, and then in 1914 was elected as president of the union.

In 1916, Gainor moved to Washington, D.C. In 1924, he represented the American Federation of Labor (AFL) at the British Trades Union Congress. He served as a vice-president of the AFL from 1935. Due to poor health, he retired from the Letter Carriers in 1941, and from the AFL in 1943.

Trade union offices
Preceded byWilliam E. KellyPresident of the National Association of Letter Carriers 1914–1941Succeeded byWilliam C. Doherty
Preceded byPeter S. Shaughnessy Anthony ChlopekAmerican Federation of Labor delegate to the Trades Union Congress 1924 With: P. J. BradySucceeded byAlbert Adamski Edward J. Evans
Preceded byHarry C. BatesFourteenth Vice-President of the American Federation of Labor 1935–1936Succeeded byGeorge E. Browne
Preceded byJohn L. LewisEleventh Vice-President of the American Federation of Labor 1936–1941Succeeded byFelix H. Knight
Preceded byDaniel J. TobinNinth Vice-President of the American Federation of Labor 1941–1942Succeeded byWilliam D. Mahon
Preceded byHarry C. BatesEighth Vice-President of the American Federation of Labor 1942–1943Succeeded byWilliam D. Mahon