Alexander Keith McClung (14 June 1811 – 23 March 1855) was an attorney from Vicksburg, Mississippi, who 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 killed as many as fourteen men in duels during his life. He was also a poet. James H. Street used him as the model for the character Keith Alexander in his novel Tap Roots (1942).