Alias Smith and Jones began with a made-for-TV movie of the previous year called The Young Country, about con artists in the old West. It was produced, written and directed by Roy Huggins, who served as executive producer of Alias Smith & Jones and, under the pseudonym of John Thomas James, at least shared the writing credit on most episodes.
- Kyle Murtry (Dennis Fimple) and Wheat Carlson (Earl Holliman), members of the Devil's Hole Gang, formerly led by Heyes and Curry;
- Harry Briscoe (J.D. Cannon), a Bannerman detective who occasionally finds himself on the wrong side of the law;
- Patrick "Big Mac" McCreedy (Burl Ives) and Señor Armendariz (Cesar Romero), two ranchers on opposite sides of the US-Mexico border/Rio Grande waging a feud over a valuable bust which represents land that had been owned by Armendariz until the river temporarily switched course, moving the border with it, allowing MacCreedy to sell the land. Heyes and Curry get stuck in the middle;
- Clementine "Clem" Hale (Sally Field), an old friend who has no problem with blackmailing the reformed outlaws when necessary. Field had appeared in only one episode before Duel's death, and she declined to return to the program. Several scripts intended for her were rewritten to feature Georgette "George" Sinclair, who was played by Michelle Lee. In the third season, Field did appear as Clem one last time;
ABC said, "No way!" They said, "You have a contract to deliver this show to us, and you will continue to deliver the show as best you can on schedule or we will sue you." Hearing those words, Universal didn't hesitate for a second to instruct us to stay in production. We were already a little bit behind the eight ball on airdates. So we contacted everybody, including Ben [Murphy], and told them to come back in. The entire company was reassembled and back in production by one o'clock that day shooting scenes that did not involve Peter - only twelve hours after his death.