Have Gun Will Travel
Starring John Dehner as Paladin, Have Gun, Will Travel brought its brand of Western adventure to CBS airwaves from 1957 until 1963. What makes it a rarity, however, is that it was television show for the entire span, but the radio version did not debut until 1958 and left the air in 1960.
The supporting cast included Ben Wright as Hey Boy. Virginia Gregg played Missy Wong (Heyboy's girlfriend) and other main roles.
Here is a sample of the online episodes currently available at The Old Time Radio Fan: