John Jay (23 June 1817 – 5 May 1894) was an American lawyer and diplomat, son of William Jay and a grandson of Chief Justice John Jay.
He was born in New York City, graduated at Columbia College in 1836, and was admitted to the bar three years later. He early became intensely interested in the antislavery movement, and while still in college (1834) was president of the New York Young Men's Antislavery Society. He was active in the Free Soil Party movement, presided at several of its conventions, and was once its candidate for Attorney General of New York. In 1854 he organized the series of popular meetings in the Broadway Tabernacle and the next year was prominently identified with the founding of the Republican Party. From 1869 to 1875 he was the United States Minister to Austria-Hungary. In 1877 Secretary Sherman appointed him chairman of the special commission to investigate Chester A. Arthur's administration of the New York Custom House. In 1883 Gov. Grover Cleveland appointed him the Republican member of the New York Civil Service Commission, of which he later became president. He published many books and pamphlets on slavery and other issues and, in 1889, was president of the American Historical Association.
He wrote an article for Appletons' Cyclopædia of American Biography about his grandfather and himself.