<Tr> <Th> Height </Th> <Td> 6'4" </Td> </Tr> <P> Roger Ewing (born January 12, 1942) is a former actor originally from Los Angeles, California . </P> <P> Ewing is best remembered 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 . </P> <P> In his first episode "Clayton Thaddeus Greenwood", Ewing's character arrives in Dodge City, Kansas, the location of the series, from Oklahoma with a warrant he is unable to execute . Among Ewing's last Gunsmoke appearances were on episodes entitled "The Prodigal", "Nitro" (Parts 1 and 2), "Ladies from St. Louis" and "Mistaken Identity". Before he was cast as Thad, Ewing appeared on Gunsmoke once in the role of Ben Lukens in the episode "Song for Dying", which aired on February 13, 1965 . </P>

Who played the role of thad on gunsmoke