Jonas King (born in Hawley, Massachusetts, 29 July 1792; died in Athens, Greece, 22 May 1869) was a Congregational clergyman from the United States who worked as a missionary, mainly in Greece. His activities in Greece were interrupted by a spell of religious persecution which was finally resolved through diplomatic negotiations between the United States' and Greek governments.
He graduated from Williams College in 1816, and from Andover Theological Seminary in 1819, and was ordained to the ministry of the Congregational Church in Charleston, South Carolina, on 17 December 1819. He then pursued missionary work in South Carolina for six months and returned to Andover for a year of graduate work. When Amherst College was founded in 1821, he was appointed professor of the oriental languages and literature, and held the chair until 1828, though he spent the years 1823-1825 working for the Palestine mission of the American Board of Commissioners for Foreign Missions in Syria distributing Bibles and preaching. To prepare himself for his missionary duties outside the United States, he had gone to Paris and studied Arabic under De Sacy.
After a brief stay in the United States in 1827/8, he was invited to accompany one of the vessels sent with supplies to the Greeks. He married a Greek woman in 1829, resumed his connection with the American Board in December of that year, and in 1831 moved to Athens, where he spent the rest of his life as a missionary. In 1832 he had established five schools, and in 1835 began to instruct a class in theology. In 1839 a schoolhouse was finished.