Producers considered actors like Raymond Burr and William Conrad but they both ended up losing the role. The reasoning behind not casting them? Producers believed them both to be too big-boned to play the part of the marshal.
They also reportedly asked John Wayne to take on the role, but he had little interest in performing on television. But guess who John Wayne recommended for the role, instead? You guessed it: his buddy, James Arness.
Thad
Roger Ewing is probably most well-remembered for playing deputy marshal Clayton Thaddeus Greenwood, AKA, “Thad,” on the show. He stuck around for two seasons before the show was temporarily canceled in 1967. When it came back on the air – Thad was nowhere to be found.
Ewing decided to try and stay off-screen as much as possible after his days on "Gunsmoke". Being an introverted person, he wasn’t thrilled about living life as a celebrity.
Casting Matt Dillon
Before James Arness landed the leading role of Marshal Matt Dillon dozens of other actors were up for the part. Among the others who almost played the show’s protagonist were actors you know and love from other projects.
Raymond Burr ended up playing the title characters in both "Perry Mason" and "Ironside" was considered for the role. William Conrad was considered first since it was he who voiced Dillon’s role on the original "Gunsmoke" radio program.
Funny Guy
After producers told Dennis Weaver to “bring the funny” into his role as Chester, he decided to kick things up a notch. He threw in a heavy country accent – and limp. But he didn’t exactly realize that by doing these things, he’d have to keep them up for 20 years.
As far as his character was concerned, Chester had gotten the limp after an injury he received fighting in the Civil War. Although some say that they believed he created the limp due to his height (six-foot-two,) after he was told executives wanted him to appear much shorter than the leading man, who stood six-foot-seven.
Polly Bond
Polly Bond was offered the role of Kitty before it was filled but she turned it down. Have you ever heard of anyone turning down a job because they were offered too much money? Yeah, neither have we, but that’s exactly what happened in this scenario.
At the time she was offered the role, Polly was married to fellow actor Tommy Bond, who played Butch on 'The Little Rascals'. Had she accepted the role of Kitty, she would have been the breadwinner in the marriage, which she apparently had no desire to do.