Not quite. Roddenberry wrote a good number of episodes, going back to the first season. But Sam Rolfe (and I think, Herb Meadow...?) actually created the “Have Gun Will Travel” series.
I actually met Sam Rolfe once. He initially wrote the fine Jimmy Stewart western “The Naked Spur.” Had a nice little discussion with him about it.
Yes, Herb Meadows. I remember from the radio voice-overs at the end of the radio version. Herb was also involved in “Frontier Gentleman”, another series starring John Dehner.
CC