"Starring" vs "Guest starring" billing on series

Does anyone what, if anything, an actor’s status as “Starring” or regularly “Guest Starring” in a TV series implies about his or her contractual relationship with the studio or production company? Naively, I would think that “Starring” cast members are under contract that they must keep themselves available for shooting/recording, while “Guest Starring” ones aren’t, but does anyone know for sure if that’s always the case in both categories?

Also, is it always the case that an actor would prefer to be “promoted” to a “Starring” credit, or would there be drawbacks? Are there different SAG rules applying in the two cases, maybe?

The main reason I’m curious, btw, is because I’ve been rewatching the original run of Futurama, and I’m struck by the fact that Lauren Tom is a “Guest Star” throughout the entire thing, despite her character, Amy, showing up in 90%+ of the episodes. I’m guessing it’s possible that she was being screwed by Fox the entire time, but maybe things aren’t so simple?

In general, “starring” are those under contract to the show. A “guest star” is someone who is not a regular, but is there for a single episode (though there are exceptions; for contractual reasons, Martin Landau was a guest star for most of his time on Mission: Impossible).

Among regular cast, “starring” are those that are better paid and have more clout – in other words, the bigger names. But there can be plenty of actors listed under that.

Nowadays, an actor can start out with a smaller role as a regular and eventually be promoted to a star (for example Robert David Hall on CSI). In general, those names in the opening credits are the stars; those regulars on the credits after the opening are not currently.

Something like Lauren Tom may be a similar situation to Martin Landau in Mission: Impossible: She was hired for a single appearance, and the producers like the role and wanted to keep her. However, the listing of the stars had already been set by contract, and the contract may have limited the number of actors who could be billed as stars. So they continued to bill her as a guest star.

As for how people are listed, the general rule is first billing is best, and last billing with an “and” or “with” is second best.

Right, but economically speaking, why might someone put (or agree to) a set limit on the number who could be billed as stars? I understand that there’s some value in distinguishing genuine starring regulars from one-off guests, but can’t that just be done via reasonable common-sense rather than setting hard limits? And, of course, regulars are generally paid more than guest stars, but correlation doesn’t imply causation: bumping Lauren up from guest starring status to regular status doesn’t, in and of itself, cost money, or take money from anyone else, unless there’s some kind of external contractual trigger that comes into play (that’s why I mentioned SAG rules?).

Anyway, it just seems semantically absurd to have her continue to be billed as a “Guest” for so long while having entire several episode plotlines revolving around her as the main character. I guess you could imagine there being an internal pissing contest among the voice-actors over who is “more important” and therefore deserving to be billed as “Starring”, but I really hope that’s not the case since it seems like a pretty petty mentality.

On the other hand, if it’s not the other voice-actors that kept her billed as a “Guest”, then I would think there had to have been some concrete economic reason for it, either on the part of the studio, or on her part.

Anyone have any idea what the real story might be, or is this just something that no one but the actors themselves and the studios would really know?

Sharif Atkins has been in nearly every episode of White Collar, in a reasonably prominent role, yet he’s still only billed as a guest star, even though he does appear in the opening title graphics.

Meanwhile Hilarie Burton was added to the cast this year, and she’s a regular “starring” cast member, but she’s been in less episodes this year than Atkins, in fact, since the show returned from the half season hiatus she hasn’t been on the show at all, though Atkins has been in them all. Apparently she does finally return in the next episode.

I’m sure there’s a good reason they’ve never bumped Atkins up to regular, but it’s still a bit silly.

There are other similar things over the history of TV (Dr. Smith on Lost in Space) but this one just particularly was on my mind since I’ve been watching new White Collar episodes lately and was just thinking about how odd it was the other night that Atkins is still a guest.