J. J. Smith may refer to:J. J. Smith, Carlow Gaelic footballer J. J. Smith (author), American author, nutritionist and weight management expert J. J. Smith or J. J. Sm., Johannes Jacobus Smith (1867–1947), Dutch botanist James J. Smith, FBI Supervisory Special agent James John Smith, American applied mathematician J. J. Smith (linguist) (1883–1949), South African linguistics