2 Dec. 1793–7 Aug. 1840
John Gustavus Adolphus Williamson, diplomat and legislator, was the son of James Williamson, a large landowner and enslaver in Person County. His mother, whose first name is unknown, was the daughter of Dempsey Moore, the first settler of Roxboro. She died not long after John's birth. His father's second marriage was to Susan Paine, also of Person County. Nothing is known about John Williamson's early education, but in 1813 he enrolled in The University of North Carolina. He did not graduate, and although he studied for the bar, he never practiced law.
Williamson spent several years in the mercantile business in New York before returning to Person County, where he was elected to the General Assembly in 1823. He served three terms in the legislature (1823–25) and became known as an Andrew Jackson–John C. Calhoun man by his support of the Fisher Resolutions.
Governor Hutchins G. Burton and Bartlett Yancey recommended Williamson for a diplomatic post, and in March 1826 he was appointed U.S. counsel to La Guayra in the new nation of Gran Colombia. The North Carolina native returned to the United States in 1832, and on 8 May of that year he married Frances (Fanny) Travis of Philadelphia.
After running unsuccessfully for Congress in 1833, Williamson resumed his diplomatic career on 3 Mar. 1835, when he was appointed chargé d'affairs to Venezuela. He was the first U.S. diplomatic representative to that South American republic. There he became well acquainted with José Antonio Páez, who governed the country as president or as master of presidents from 1830 to 1846. One of Williamson's major accomplishments was the negotiation of a Treaty of Friendship, Amity, and Commerce between the United States and Venezuela in 1836.
Frances Williamson was unhappy in Venezuela, and she returned to Philadelphia in February 1840. After her departure Williamson's health deteriorated steadily; he died six months later and was buried in the English cemetery in Caracas. In his will he left two large paintings to the Dialectic Society in Chapel Hill. One of these was probably a portrait of Venezuelan president Páez painted by the English artist L. B. Adams. What happened to these paintings or whether the Dialectic Society ever received them is unknown. A manuscript copy of Williamson's diary is in the William T. Morrey Collection at Louisiana State University.