| State1: | Nebraska |
| District1: | 3rd |
| Term Start1: | March 4, 1903 |
| Term End1: | March 3, 1907 |
| Preceded1: | John Seaton Robinson |
| Succeeded1: | John Frank Boyd |
| Party: | Republican |
| Birth Place: | Stoughton, Wisconsin |
| Birth Date: | 19 July 1857 |
| Occupation: | lawyer |
John Jay McCarthy (July 19, 1857 – March 30, 1943) was a Nebraska Republican politician.
Born in Stoughton, Wisconsin, on July 19, 1857, he attended Albion Academy.[1] He moved to David City, Nebraska, in 1879 and to Dixon County, Nebraska, in 1882.[1] He married Ellen "Nellie" McGowen (1862–1920) in 1883.[1] He was admitted to the bar in 1884 and set up practice in Emerson, Nebraska.
He was elected prosecuting attorney of Dixon County in 1890, 1892, and 1894. In 1898 and 1900, he was elected as a member of the Nebraska House of Representatives. In 1902, he was elected as a Republican to the Fifty-eighth and Fifty-ninth Congresses and served Nebraska's 3rd district from 1904 to 1908.[1] [2] He ran in the 1906 primary and lost to John Frank Boyd. He continued with his law practice in Ponca, Nebraska,[3] not serving in any other elected office, though he was a delegate to the 1912 Republican National Convention. He died in Ponca on March 30, 1943,[3] and is buried in Ponca Cemetery.