Alexander Keith McClung (14 June 1811 – 25 March 1855) briefly served as US chargé d'affaires to Bolivia in President Zachary Taylor's administration. An "inveterate Southern duelist" nicknamed "The Black Knight of the South", he was also a poet. James H. Street used him as the model for the character Keith Alexander in his novel Tap Roots (1942).McClung was born in Fauquier County, Virginia, and was the nephew of John Marshall. He served as lieutenant colonel of the 1st Mississippi Regiment during the Mexican–American War. He committed suicide in the Eagle Hotel in Jackson, Mississippi.