The opening credits for each episode of Babylon 5 Season 2 (which you can see in this video) include the actors for the following characters:
- Captain John Sheridan
- Lt. Commander Susan Ivanova
- Security Chief Michael Garibaldi
- Dr Stephen Franklin
- Talia Winters
- Warren Keffer
These are almost all main characters: the four humans on the command staff, the station's telepath, the three Ambassadors (not counting Kosh, who hardly ever shows up and you never see his face anyway) and their assistants, and ... Warren Keffer. When I saw him in the credits, I assumed he was going to be a new main character for Season 2, but we only see him in a few episodes and he only plays a major part in one or two. For that matter, the same could be said for Na'Toth: we see a lot of Vir and Lennier, but she just fades out of the picture after a few episodes near the start.
Why are such minor characters as Keffer and Na'Toth included in the credits?
Was it a contract thing? Were their actors some famous people who demanded a lot in exchange for appearing on the show? Or was it JMS's decision, for some reason as yet unclear?
If the answer involves spoilers from seasons 3-5, please mark them as such.