- Lorne Greene as Ben Cartwright
- Dan Blocker as Eric "Hoss" Cartwright
- Michael Landon as Joseph "Little Joe" Cartwright
- Pernell Roberts as Adam Cartwright (Seasons 1-6)
Recurring Actors:
- Victor Sen Yung as Hop Sing, the family's Chinese cook
- Ray Teal as Sheriff Roy Coffee
- Bing Russell as Deputy Clem Foster
- Guy Williams as Will Cartwright (Season 13)
- Mitch Vogel as Jamie Hunter-Cartwright (Seasons 12-14)
- Tim Matheson as Griff King (Seasons 13-14)