Arthur Tatum Jr. (/ˈteɪtəm/, October 13, 1909 – November 5, 1956) was an American jazz pianist who is widely regarded as one of the greatest ever. From early in his career, fellow musicians acclaimed Tatum's technical ability as extraordinary. Tatum also extended jazz piano's vocabulary and boundaries far beyond his initial stride influences, and established new ground through innovative use of reharmonization, voicing, and bitonality.