A Sub-Trope of Geographic Flexibility, when writing a small town setting for long enough, you start introducing new characters everyone apparently knows, but has never mentioned before. In Police Procedural and medical shows, new neighbours are handy for Ripped from the Headlines and Subculture of the Week plots.
Compare/contrast One-Neighbor Neighborhood, where the main characters only seem to have one set of next-door neighbours.
- Sam & Max: Averted in the videogames though; Bosco, Stinky and Sal are neighbours of Sam and Max who are mentioned long before their on-screen introductions.
- In the early 1980s, The Dukes of Hazzard had several coloring book adaptations. One of the books contained a story about the Duke family's new neighbors, who were never seen in the original series. note
- This happens in the Mary Minor, Mrs. Murphy and Tee Tucker mystery series written by Rita Mae Brown. The series is set in a small town in Virginia and there are always at least a few new characters introduced with each novel.
- R. L. Stine's Ghosts of Fear Street series. It must be one long street...
- Some characters don't live on Fear Street, but if they don't, they do something that involves Fear Street or the also-cursed forest and lake beside it.
- In Anne of Avonlea (sequel to Anne of Green Gables), Anne has a new next-door neighbor, Mr. Harrison. She also makes the acquaintance of the reclusive Miss Lavender. Anne begins teaching in the one-room schoolhouse where she was until recently a pupil, and the small student body includes 10 children who have just moved to town.
- Early seasons of Smallville had a new meteor rock freak every week.
- Everwood, including the flavor of the week patients.
- British police show Heartbeat takes place in a small town of Ashfordly, which seems to have a ready supply of people committing various crimes, and in later seasons suffering from alcoholism and needing An Aesop.
- Murder, She Wrote, complete with one of the new characters dying in the episode they are introduced. Seems like Cabot Cove is the murder capital of the east coast.
- They poked at the edges of the trope; there were a number of recurring Cabet Covers beyond Jess, Doc Hazlett and the sheriff, and even two episodes where one of these recurrers was the murderer, which the Genre Savvy know isn't supposed to happen.
- Cardale in Peak Practice, another medical show example. Possibly lampshaded in one episode:
"Who'd have thought we had a world class jazz musician in our town?"
- The character of Kate and her mother Rebecca in Robin Hood have apparently lived in Locksley all their lives, even though it's a reasonably small village and they've never been seen or referenced before Series 3. Making it all even stranger, Robin is on first-name terms with Rebecca, yet doesn't recognize or know who Kate is during their first on-screen interaction.
- The "small town" of Eureka keeps adding new characters to the point where Carter, who's been there approximately five years by now, still doesn't know everyone (or even, apparently, most people).
- Midsomer Murders takes an entire county of small towns as its setting, but it's been running so long that this is a problem anyway. Justified, as nearly every episode has 3 or more deaths and without new neighbours, there would be hardly anyone left.
- Buffy the Vampire Slayer and related media. Handwaved in that the Hellmouth the town is on attracts the monsters and scaries.
- Star Trek: The Next Generation did this a few times, most notably in the episode "Lower Decks" which introduced a set of brand-new Starfleet officer characters ... only for them to never be seen nor referenced again. One of these one-off characters is shown to be Ten-Forward's secondary bartender (in lieu of Guinan) who is well-known enough to be a confidante, but had never been referenced before or since.
- Voyager did this too, with the twist that the "new" characters were in fact the three bottom-performing crewmen on the ship.
- Little House on the Prairie did this a lot, most noticeable during the first season with students. An episode would center around a student who couldn't read or was disabled or whatever lesson of the week required. Every other child would know who they were and what their problem was, as if that student had always been there. Yet, we'd never seen them before and never saw them since. Averted in some early episodes when a few of the school children played by regular extras were slowly given the odd line, a name and once or twice worked into the plot directly for an episode.
- Father Ted based in a tiny village on a tiny island off the coast of rural Ireland suddenly mentioned the village had a Chinatown section. Naturally this happens the very moment Ted has put a conical lampshade on his head and squinted his eyes before spotting a Chinese family at the window.
- On Charmed, the position of the Halliwell Manor's next-door neighbors could be filled by a new character, Muggle or magical, at any time.
- Enemy at the Door is set on the island of Guernsey during World War II. New islander characters are often introduced as acquaintances of the main characters, and sometimes implied to be close friends they're regularly in social contact with (as for instance the Prideux family in "The Polish Affaire"), but will nevertheless, with very few exceptions, appear for only one episode and never appear or be mentioned before or since.
- In the first few days of playing Animal Crossing, a new neighbor moves in every day.
- WarioWare series. Not explicitly stated how big Diamond City is as a place, but each game adds new characters apparently just living a few houses away from each other that have never been seen before in the entire series.
- Arguably The Sims, in particularly The Sims 2 and 3 if you're following the stories of the Maxis/EA premade families. Can also happen quite literally with Story Progression, which sometimes will randomly generate families to movie into houses.
- The Reality-On-The-Norm Shared Universe is set in a city which seems to gain more and more citizens with each installment.
- Over the course of its decade-plus run, The Inexplicable Adventures of Bob! has fleshed out Generictown this way. Usually when a townsperson pops up who we've never seen before, Bob already knows them. Justified, since it's a small town Bob has lived in all his life. They generally continue to appear once introduced. Surprisingly, he didn't know Jean when she first appeared, despite the fact that she lives nearby. Granted that she didn't grow up there, but she's implied to have lived there for several years.
- The Simpsons:
- Springfield started out this way, until all the side characters were cemented as a part of the cast.
- While the Flanders family have been the next-door neighbors of the Simpsons for the entire series (save for a few brief moves), the house on their other side has changed tenants frequently. The Winfields, an elderly couple, were their original neighbors until they sold the house in season four, then Ruth and Laura Powers lived there for a few seasons. Since then, neighbors appear at random, then disappear, never to be mentioned again. Sideshow Bob wearing someone else's face also lives in the house for an episode.
- More distant neighbors are seldom specified, although Mrs. Glick seems to live on the same street somewhere and the house across the road was once owned by George Bush and then Gerald Ford.
- That huge house opposite the Simpsons certainly seems to pop out of nowhere.
- Or is an empty lot big enough to drive an SUV through, as it is in the Canyonero episode.
- Several major buildings change locations and neighbours depending on what a joke or plot demands. Taken to its logical extreme in the Movie, in which Moe's Tavern is temporarily moved to be a standalone block for a joke about the churchgoers and barflies switching activity because of the dome's appearance. Later in the movie, we can see Moe's Tavern has returned to its usual location by watching the background.
- Fillmore! reuses the faces of previous episodes' characters, but they never speak or do anything of importance. Outside the safety patrol itself, no character features in more than one episode, even those who have a history with the regulars.
- Kaeloo parodied this in episode 54, which introduced new characters Pretty and Eugly. Stumpy looks at them in shock for a moment before turning to Kaeloo and asking who they are, and she tells him they're their neighbors, and is somewhat surprised he doesn't know.