| John T. McDonough | |
| Office2: | 8th Associate Justice of the Supreme Court of the Philippines |
| Appointer2: | William Howard Taft |
| Term Start2: | February 18, 1903 |
| Term End2: | May 1, 1904 |
| Predecessor2: | James Francis Smith |
| Successor2: | James F. Tracy |
| Office: | Secretary of State of New York |
| Term Start: | January 1, 1899 |
| Term End: | December 31, 1902 |
| Governor: | Theodore Roosevelt Benjamin B. Odell |
| Predecessor: | John Palmer |
| Successor: | John F. O'Brien |
| Birth Date: | 12 July 1843 |
| Death Place: | Washington, D.C., U.S. |
| Alma Mater: | St. John's College Columbia Law School |
John Thomas McDonough (b. July 12, 1843 Birdhill, County Tipperary, Ireland - d. March 21, 1917 Washington D.C.) was an American lawyer and politician.
He came with his parents to the United States in 1850, and they settled in Dunkirk, New York. He graduated from St. John's College, and studied law at Columbia Law School, finishing as Bachelor of Laws in 1861. He was admitted to the bar in 1869.
He served two terms as Police Magistrate at Dunkirk, N.Y., and in 1876 was elected Special Surrogate of Chautauqua County, New York, serving until 1878. Afterwards he resumed his law practice, at times in New York City, in Buffalo, New York, and from 1881 on in Albany, New York. In 1884 he ran for Recorder of the City of Albany, but was defeated. In 1891, he ran in the Third Judicial District for Justice of the New York Supreme Court, but was defeated by Democrat D. Cady Herrick. He was a delegate to the New York State Constitutional Convention of 1894. In 1896, he was appointed by Governor Levi P. Morton New York State Commissioner of Statistics of Labor.
He was Secretary of State of New York from 1899 to 1902, elected in 1898 and 1900. In 1899, his old college conferred the degree of Doctor of Laws on him. From June 17, 1903, to May 1, 1904, appointed by President Theodore Roosevelt, he was an Associate Justice of the Supreme Court of the Philippines. He was a delegate to the 1904 Republican National Convention from the Philippines.
In 1907, he ran on the Independence League ticket for the New York Court of Appeals but was defeated.
He was President of the Dulangan Mining Interests Co., Inc., Director of El Oriente Fabrica de Tabacos, Inc., Managing Director of the Golden Gate Mining Association, and a member of the Board of Directors of the Philippine Realty Corporation.