Why do some actors (actresses) get a credit without appearing in an episode? If it matters, I am specifically referring to sit-coms of the 1970s and 1980s. I recognize the actors’ strike did a lot to get them credit for the slightest thing…but not appearing? How can I get in on this! 
For example…?
I assume it’s a contractual requirement, that even if the actor doesn’t appear in the episode, he’s still listed in the credits. I think this is when the actor is a regular cast member.
It still happens - for example, Seth Green and Mila Kunis are credited as being in every episode of Family Guy (well, Kunis is once she took over her role), but there have been quite a few episodes over the years where Chris and/or Meg had no lines. In fact, there was one episode (Brian and Stewie get locked in a bank vault) where Seth MacFarlane had all of the speaking parts, yet all of the show’s stars still got credited.
For TV, if your part of the main cast you are credited even if you don’t appear in the episode. This has been the situation singe the beginning of TV. James Arness, for instance, didn’t appear in episodes of Gunsmoke from time to time to give him a break. Bonanza would sometimes concentrate on one of the characters and leave out another. Their contracts guarantee they are part of the credits for all episodes of the show.
For movies, it’s often because the actor’s role was cut out in editing. In My Favorite Year, Philip Bruns gets a credit but only appears in a crowd scene at the end. I’ve seen The Last Fighter several times and still haven’t spotted Wil Wheaton (possibly I just don’t recognize him because he was so young), but he got credit.
The opposite was Victor Killian in Unknown World, who was one of the leads but got absolutely no credit. This was an artifact of the Blacklist – Killian had been named a communist sympathizer so the producers hid the fact he was in the movie.
Jinx, You do understand that credits are produced once and rarely changed, right? Some shows ran their credits unaltered for years on end. That’s because credits are often produced by specialty outside firms who charge enormous amounts for their services. Are you really suggesting that the credits be edited every single week to reflect who happens not to be in an episode? Who would go to all of that expense? Making the series theme song fit to a shorter cast alone would be a ridiculous chore. And for what purpose?
To repeat what Chuck said. The credited actors’ contracts require that they be billed in every episode. That has been the practice for every kind of show since the dawn of television, not just 70s and 80s sitcoms. It’s happening today if you turn on your television and look.
In Indiana Jones and the Last Crusade Alex Hyde-White received credit for appearing as a “young” Professor Henry Jones (the Sean Connery Role in the rest of the movie), even though his scenes all got cut. I think there’s a still photo of him as Young Prof. Jones, but that’s it. (imdB implies that it’s his hands we see in the opening sequence but I’m not convinced.)
Why does it count as an “appearance” if the star of the show is in one scene that week, where he tells the costar, “I’m off to my conference. Don’t forget to water the plants,” and disappears for the rest of the episode?
There is a difference between Series Regular and Reoccuring Guest. In general the regular is under contract and gets paid the same regardless of their workload. The reoccuring guest gets paid according to what they work and can be cut out any time. Or they can be in every episode.
A series regular is going to be in the credits regardless of how much they are in the episode. Or not at all.
Some examples:
Cirroc Lofton was a series regular on Star Trek: Deep Space Nine even though he appeared in only about half the episodes. He was paid a set salary for each season and got a regular check whether he had to work that week or not. He was in the opening credits of every episode.
Diana Muldaur appeared in every episode of the second season of Star Trek: The Next Generation but was not a series regular. She was a guest star every week. Her name did not appear in the opening credits, but she got guest star billing after the credits. If she had not appeared in an episode, she wouldn’t have been paid that week, but as it turned out, they used for every one.
Because his contract says so.
Additionally, the Screen Actors Guild rules probably dictate that the contract be of that form and that a credit be defined that way.
Martin Landau was a “Special Guest Star” during the entire first season (and possibly more seasons) of * Mission: Impossible*, even though he was in every episode. Landau was a guest star in the pilot, and the producers decided they wanted to keep him as a regular. But the contracts were signed, so he couldn’t be credited as a regular.
Ironically, in the episode “Zubrovnik’s Ghost,” Barbara Bain and Peter Lupis did not appear, so Landau, who was in every episode, appeared in more episodes than two of the regular cast.
“Also starring Barry Morse, as Lt. Phillip Gerard.” Maybe a third of the time.
Glee had a large cast that included several performers who changed contract status during the run of the show, and as a result the opening credits often didn’t very accurately reflect who you’d actually be seeing that week or even who the most important characters were that season.
For instance, Terri (Jessalyn Gilsig), the wife of choir teacher Will Schuester, was a major character in the first season but only occasionally appeared in later seasons. However, Gilsig continued to be credited as a series regular in every episode of the second season even though Terri wasn’t even mentioned in most of them. Meanwhile, the character Blaine (Darren Criss) was introduced early in the second season and appeared in more than twice as many episodes as Terri that season and in a far more prominent role. But during that season Blaine was considered a recurring character so Criss was only credited when he actually appeared. (He was promoted to the main cast the following season.)
Barbara Barrie was listed in the credits for the first two seasons of Barney Miller as Miller’s wife. She appeared in less than half the episodes during that run. They originally planned to show more of Miller’s home life, but quickly decided to keep everything in the station.
The Americans from 1961 was the story of two brothers who fought on opposite sides of the Civil War. Both Darryl Hickman and Richard Davalos were credited each show, but, of course, only appeared in the same episode a couple of times.
The Roaring 20s had three male leads. All were credited, but usually they only showed one of them in an episode.
“…and Rex Hamilton as Abraham Lincoln.”
I suppose Green and Kunis sing at least one line during the show’s opening theme (“…on which we used to rely…”) so they are indeed in every episode.
Example: Katherine Heigl in season 6 of Grey’s Anatomy.
She took a maternity leave (adopting, FWIW). But announced she didn’t want to come back. Wanted to do movies.* Missed 5 out of 7 episodes. Credited in those 5 since she was just “on leave”. After her last appearance continued to be credited for 6 more episodes while the behind-the-scenes contract stuff was petering out and new credits made. Not credited for the last 6 episodes of the season.
People can also be continued in the credits after they die in part as an in memorium. E.g., from Hill Street Blues:
The great Michael Conrad was listed for 6 more episodes after his last appearance, which itself was aired after his death.
Yeah, well. Normally the singers of a theme song are never listed in the main actor credits, or else John Sebastian would have been credited on every episode of Welcome Back, Kotter.