Here's a rundown on all of the main characters that you can expect to see on 'Gunsmoke,' one of the longest-running shows of all time.

Mary Evans/AF Archive/Everett Collection Roger Ewing played young deputy Thad Greenwood. CBS Photo Archive/Getty Buck Taylor played Newly O'Brien on 'Gunsmoke.' ...

Roger Ewing’s time on Gunsmoke was brief, but he was credited as part of the main cast. He played Thad Greenwood and was originally intended to replace Arness if contract negotiations went south.

Roger Ewing with James Arness on “Gunsmoke.” Ewing played deputy marshal and handyman Clayton Thaddeus “Thad” Greenwood in 36 episodes from 1965 to 1967.

Roger Ewing as Thad Greenwood Mary Evans/AF Archive/Everett Collection Roger Ewing played young deputy Thad Greenwood. Roger Ewing portrayed the young deputy Thad Greenwood from 1965 to 1967. Born in ...

Reynolds also departed that season, replaced by Roger Ewing’s corn-fed giant Thad Greenwood, who only lasted two years himself. Next Gunsmoke transitioned to color after 11 seasons in black-and ...

‘Gunsmoke’ aired from 1955 to 1974 and set a new standard for TV drama. See what happened to cast members James Arness, Milburn Stone, Amanda Blake, Burt Reynolds and more.

Roger Ewing as Thad Greenwood Mary Evans/AF Archive/Everett Collection Roger Ewing played young deputy Thad Greenwood. Roger Ewing portrayed the young deputy Thad Greenwood from 1965 to 1967. Born in ...