In most ongoing series, there are several job positions that need to be filled. Often, these roles will be filled by the characters of a Five-Man Band. But in some series, there is one specific job that tends to have a high turn-over rate. This allows the author to keep bringing in new characters who have skills useful to that particular story or who can betray the operation from the inside.
When played straight, these positions become an obvious Chekhov's Gun; whoever the "new guy" is, everyone knows that they will become significant later on. However, this character can still turn out to be no more or less relevant than anyone else.
The nature of this job lets the writers kill this character off, if they want to, usually in some emotionally significant way. Retirony may come into play. Characters in Dead End Jobs do tend to hang around long enough for viewers to get attached, Chekhov's Gunman or not.
When done poorly, the audience may start wondering why the HR department doesn't get rid of the job altogether and delegate that work to established and trustworthy characters.
Please note that this trope does not apply to Red Shirt characters of the type you tend to find on Star Trek. Characters who hold jobs of this type tend to last for a full plot arc, be significant to that plot arc, and then get conveniently shuffled off-screen at the end to make room for the next plot-significant character.
A sub-trope of High Turnover Rate.
- This Is Spın̈al Tap has a running gag where the band's drummers keep dying in improbable ways, to the point that when their keyboard player dies, they find out that he used to be a drummer.
- The job of Defense Against the Dark Arts professor in the Harry Potter series. In seven books, they go through seven professors, and every one of them is significant to the plot. Dumbledore even lampshades this at one point. As it turns out, Voldemort had jinxed the job so that no one who got it could hold it for more than a year, and this persisted until his death.
- The position of Postmaster General in Going Postal. Vetinari gives the job to Moist Von Lipwig as an alternative to being hanged, on the off-chance that he might actually succeed in reviving the Post Office, but generally expecting him to be killed, as the job had already claimed the lives of some of Vetinari's clerks.
- The Bastard Operator from Hell series has the post of Systems Supervisor as this, with said supervisor being killed off by the BOFH or the PFY once they become too dangerous. Whether or not this can also be said for the Director of IT post is debatable.
- In one of Isaac Asimov's Azazel stories, the first head of the Committee on Diminishing Returns lasts thirty-two years, the next one sixteen, the next one eight... After the sixth, they decide the Committee's name must be unlucky, and a change is in order. It works.
- Night Court had a problem hanging on to female bailiffs. The first two, Selma and Florence, were elderly women who both passed away when their actresses passed in real life. The third bailiff, Roz, made it to the end of the series, though did have a diabetes scare.
- The President of the United States is this in 24. During the series there are 7 acting presidents shown on screen and two more off screen (Palmer's VP is acting president in The Game and whoever was President during season 1) across 8 seasons and in the series finale the current President resigns!
- The position of explosives expert in Tagon's Toughs in Schlock Mercenary has a relatively high turnover rate: So far it's killed at least two Mauve Shirts who have held it (Kevyn, their unofficial expert, has also died repeatedly). Many of the grunts believe the position to be cursed, although its current holder doesn't seem too fussed.
- South Park's constant killing of Kenny is a parody of this trope, although being as Kenny continues to be a cast member, ultimately is an aversion.