Big Elk (Om-pah-ton-ga), ca. 1772-1846 (Omaha) was principal chief of the Omaha Nation and a noted orator.  Visiting Washihgton, D.C. in 1821-1822, he was a member of the first Native American delegation to be painted by King.  Ompahtonga may also be the third subject in one of King's greatest works, "Young Omahaw, War Eagle, Little Missouri, and Pawnees," a group portrait of the 1821 delegation which is in the Smithsonian American Art Museum.  The work can be seen at http://www.nmaa.si.edu/.  George Catlin (1796-1872) also painted a portrait of Big Elk at Fort Leavenworth in 1832.