for his characterization of part-time deputy marshal Clayton Thaddeus "Thad" Greenwood in thirty-six episodes (October 2, 1965 - September 25, 1967) of the long-running CBS western television series Gunsmoke with James Arness . Among Ewing's last Gunsmoke appearances were on episodes entitled "The Prodigal", "Nitro" (Parts 1 and 2), "Ladies from