I think it is safe to say no one will exceed the late James Arness’ continuity as an actor in the same show, playing the same character.
Certainly Lucille Ball’s TV career was longer, but there were breaks.
Kelsey Grammer matched Arness in playing the same character for twenty years, but his portrayal of Doctor Frasier Crane was split between two series. However, he may already own a record as the longest-lived recurring character as Sideshow Bob in the Simpsons.
My favorite Arness role was far removed from the Hollywood Western genre – the creature in The Thing. My choice should come as no surprise to anyone who knows me: I am hooked on sci-fi classics.
One of the most memorable scenes involving Arness’ character in the 1951 feature was performed by a stunt double. Here it is:
Rent it. The movie has held up very well over the years.