| James Clemens Jr. | |
| Birth Date: | 29 October 1791 |
| Birth Place: | Danville, Kentucky |
| Death Place: | St. Louis, Missouri |
| Occupation: | Businessman, banker |
James Clemens Jr. (October 29, 1791 in Danville, Kentucky – January 12, 1878 in St. Louis, Missouri) was an American businessman and banker.
Clemens Jr. was the second son of four children of Jeremiah Clemens (Loudoun County, Virginia, September 16, 1763 – Danville, Boyle County, Kentucky, June 8, 1826), and wife (m. ca 1788) Jane Cochran (1764 – April 7, 1821). They went to Kentucky (then the District of Kentucky, Virginia) in 1787, where he operated "The Big Black Horse" tavern in Danville. His older brother Thomas Clemens (February 27, 1790 – July 30, 1826) died unmarried and without issue. His younger sisters were Elizabeth Clemens (1802 – living 1878) married with Charles Caldwell, and Isabella Clemens, married in 1833 with Thomas Reed.
He started his career engaged in mercantile business with his uncle James Clemens Sr. in Huntsville, Madison County, Alabama (then in Mississippi Territory). He then moved to Missouri, then part of Missouri Territory, in 1816, where he became a successful storekeeper. Later he became active in banking. He did much to help the family of Mark Twain, of whom he was a relative.[1]