casting - What rules govern how TV show opening credits are structured?

The rules for how the order of credits is produced is very long and convoluted. They also vary from show to show, so for any one "rule of thumb" it's almost guaranteed you can find an exception on the air right now on some channel.

The basic guidelines that most shows follow most of the time are drawn from the rules for the various industry guilds. In the case of actors, that would be SAG (the WGA and DGA would determine how/when a writer or director get credited.) The Wikipedia articles linked in a few comments/answers gives a basic rundown of all the guild rules that have to be followed in the "typical" credits sequence. Note that movies opening and closing credit sequences differ a lot from television ones (in particular, you rarely see the name of the production company in a TV show's opening credits.)

However, there's a lot of variation on the basic theme, because the placement and styling in the credits sequence is often part of an actor's individual contract with the studio. Studios will rearrange the credits or give certain actors special consideration in the credits as part of the negotiations.

The basic flow of credits is as you mentioned: core actors first, followed by guest actors, followed by a handful of top-level production staff. In TV, it's rare to have a full set of closing credits the way you have in movies, where the entire cast would appear with their character names, for simple time reasons: they would take a really long time that could instead be used for commercials. (In fact, many networks now show split-screen closing credits side by side with a promo for the upcoming program.) So those credits are usually limited to production-level people and companies, copyright/legal notices, and other minutia.

Why a particular actor gets a particular spot in the credits is mostly a matter of PR, and explains some of the variations you mention in your question:

• Being billed before the title is "more prestigious" than after the title; usually only the one or two top-tier stars will get this billing, if at all. In ensemble shows it's rare to see this type of split billing.


• Actors are generally billed in rough "order of importance" to the show.


• Being billed last, however, is also considered a key position, as long as it is somehow differentiated from the rest of the cast. For example, in the Buffy TV show, Anthony Stewart Head (arguably the most "famous" cast member prior to the show) was billed as "and Anthony Stewart Head as Giles" - the only cast member whose character was named.


• Since the opening credits are pre-recorded, typically only season regulars make it into the "core" credits sequence (think "theme music") for shows that have them. Recurring guest stars are usually billed overtop of the opening scene, introduced with "Also Starring".


• Single-episode guest stars go last; depending on how famous/important they are, they may also get the "as charactername" treatment.

In general, having a unique style of credit (e.g. being specifically associated with a character) is a bonus given out to special guest stars and particularly important actors that lets them stand out from the rest of the cast. This is something a well-known or highly-priced actor would negotiate as a condition of their appearance. They even negotiate down to the exact wording, which can include "guest" vs. "special guest", are they "starring" or "appearing", etc (I have seen shows that had multiple guest stars, each billed slightly differently).

Another key distinction to make is between series regulars and recurring guest stars. A series regular will still appear in the opening credits, and be given credit for the episode, even if they don't actually appear in the episode.

The general idea here is that a series regular, even if they aren't in a particular episode, is contractually required to be available to appear in that episode. A recurring guest actor, on the other hand, is typically contracted to appear in only a specific number of episodes, and can usually skip a particular episode if they have prior commitments. A recurring guest star, with lower billing, may actually get more screen time than a series regular that gets top billing. This happened in House in seasons 4-6, where Olivia Wilde, Kal Penn and Peter Jacobson were given lower "Also Starring" billing, while rarely-appearing Jennifer Morrison and Jesse Spencer continued to be billed as series regulars. As always, this was entirely down to the contracts the latter two had with the show.