John Kelly, 1822–86, American politician, boss of Tammany Hall, b. New York City. He entered politics at an early age. At first he opposed Tammany Hall, but later (1853) joined the organization and became city alderman. He served (1855–58) in Congress and was (1859–61, 1865–67) sheriff of New York County. After the exposure of William M. Tweed, Kelly, by then popularly known as
reorganized the Tammany machine. By 1874 he held control of the organization and carried on continuous warfare with the faction of Samuel J. Tilden, who originally had cooperated with him in reorganizing Tammany. Kelly's refusal to back Tilden's candidate for governor, Lucius Robinson, and his decision to run for governor himself as an independent helped bring about the election (1879) of Alonzo Cornell. While he was head of Tammany, Kelly was able to determine the course of New York City elections, and he himself was city comptroller from 1876 to 1880. Upon retirement (1884) he yielded his political control to one of his lieutenants, Richard Croker.
See M. R. Werner, Tammany Hall (1932, repr. 1968).