Also tends to happen to the Doom Patrol. Often lampshaded at the end of their newest guest appearance in some other hero team's series.
The thirdFlash, Wally West, was hit with this pretty hard. He started out as the original Kid Flash, before replacing Barry Allen as the Flash (And becoming the Trope Codifier for Sidekick Graduations Stick) following Crisis on Infinite Earths; even being used as the Flash over Barry in Justice League. After that, Wally remained the main character in the Flash series until Infinite Crisis, when Bart Allen briefly took over the role for a year before Wally returned, at which point Wally took the series over again. Until Final Crisis brought Barry Allen Back from the Dead & he took the book back from Wally; and although they both remained active as the Flash, Wally only made two appearances in the Flash series after that point & was effectively reduced to appearing in crowd shots, until DC launched their line wide reboot & Wally was "taken off the table" with his tenure as the Flash & Kid Flash seemingly completely retconned away. Given that Wally is one of DC's most popular characters, fans were deeply unhappy with this. Wally has been reintroduced as Iris West's troubled delinquent nephew and Barry is starting to take on a mentor role with him, so he does have a part in the reboot.
It also happens a lot to the Legion of Super-Heroes, given the sheer number of characters, frequent RetCons and all-out continuity reboots, generally convoluted continuity, and the fact that the team has been in existence since the 1950s, giving fans plenty of opportunity to start Running the Asylum. The most notable victim is probably Dyrk Magz aka Magno, who spent all of ten issues as a member of the Legion before getting summarily depowered, was given just enough development to be interesting, and then mostly got relegated to the background before the Legion Worlds miniseries finally managed to abandon the character in a way that gave him no resolution but also left him in a position from which it would be hard to bring him back into play. And then the Legion's continuity was rebooted entirely a few years later anyhow. Also notable were Wildfire and Dawnstar, who were amongst the most popular characters of the original Legion.
The Legion was also the cause of this for another hero: Superboy. They originally appeared as supporting characters in a 1958 Superboy story, then starting in 1962 they appeared as the backup feature in Adventure Comics where Superboy had been the star since 1946. Within a year they had taken over the comic, reducing Superboy to the back up in what had been his title, and not long after solo Superboy stories stopped appearing altogether (though he continued to appear as a member of the Legion.) A decade later they repeated the feat when they started appearing in Superboy as a backup feautre, which was renamed Superboy and the Legion of Super-Heroes and eventually just Legion of Super-Heroes as they again took over the comic and Superboy got Put on a Bus.
In the later years of the feature, Toni Turner, best friend to Millie the Model, seldom appeared, her role largely supplanted by "Millie's Redheaded Rival," the nastier and more colorful Chili Storm.
In Paperinik New Adventures all the important supporting cast of Donald Duck(Uncle Scrooge,his nephews a Daisy)were reduced to third-grade characters or cameoes to make place to new characters.
Harry the Head was originally a major character in Oink!, with his strip occupying a full page each issue, and having a number of multi-part adventures. In later editions, his strip had been reduced to an occasional three-frame gag.
This happens in Sin City, mostly because different stories have different protagonists. For instance, Marv was the main character in the first story and a supporting character in the second. Aside from two one-shots, he was never the main character for any stories after that. Later stories have him showing up as an extra in the background (often if the scene takes place at Kadie's Bar) with one or two lines. Word of God states that he will be the focal point in future tales.
Rotor Walrus in Sonic the Hedgehog, both SatAM and Archie Comics versions, have been hit hard with this; in both versions, he started out as a strong fixture in the Freedom Fighters, then got kicked into this position after a certain point (Season 2 in SatAM, issue #125 in the Archie Comics); in fact, in the comics, his jacked-up importance and Word of Gay relationship in the "Mobius: 25 Years Later" storyline was meant by previous head writer Ken Penders as a way of moving him out of extra status and giving him a much-needed jolt of Character Development. Sadly, when current head writer Ian Flynn took over, he was beaten back down to this spot violently, in both the main comic and the "M:25YL" storyline for quite some time. He eventually regained some prominence when he joined the Royal Council and later made himself a high-tech suit, but not until he'd been largely unseen for several years.
A group of characters called "The Substitute Freedom Fighters" faded out of relevance soon after their introduction. Currently, they were brought back as councilors on the royal council. One of them, Hamlin, was angry enough about his treatment that he joined the council out of spite for the Freedom Fighters.
Knuckles has also been demoted heavily since his own spin off comic series ended, likely due to his life on Angel Island making it harder to focus alongside the Freedom Fighters down on Mobius.
Interestingly, Sonic himself was affected by this - after the Knuckles comic got cancelled, Sonic was limited to mostly being stuck in Knothole following the Sonic Adventure adaptation, with Knuckles and Tails getting a lot of the screen time and action in their backup stories, due to a case of Creator's Pet.
A lot of this is Lampshaded in the "Off-Panel" comic strips at the end of the Sonic Universe comics, from Knuckles flipping out over the title not exactly being his to Charmy commenting that if he was going to show up in a storyline, it would be here.
Some Spider-Man editors have been quoted saying "Spider-Man has a supporting cast?". This is because most supporting cast members are either lost in limbo or have been killed off. On the other hand, some creators and fans like to boast that Spider-Man has the best supporting cast in comics. The cast evolved, with some characters - notably Aunt May, J. Jonah Jameson, and Mary Jane Watson - emerging as very resistant to efforts to write them out. But important supporting characters being killed off or consigned to Limbo has been a hallmark of the series since Stan Lee's days. The first notable character Demoted to Extra was Betty Brant, Peter Parker's main love interest until he started college (her rival Liz Allan was Put on a Bus slightly earlier).
The Spider-Man series provides some super-villain examples.
Shriek was introduced in 1993 to form an Unholy Matrimony with Carnage. She also acted as Team Mom with three younger supervillains they recruited. She was a featured player in a couple of major storylines, and made regular appearances to 1996. Since then she has made only infrequent appearances in crowd scenes.
Doctor Octopus died in 1995, and soon got an Affirmative Action Legacy in Doctor Octopus II/Dr. Carolyn Trainer. From 1995 to 1997 this Hot Scientist was one of the most frequently used villains of the Spider books. Then the original got resurrected through a necromantic ceremony and she was Demoted to Dragon for him, then forgotten. She has since resurfaced a few times as an easily-defeated third-string villain.
Scorpia was introduced in 1995 as a Distaff Counterpart to Scorpion, with the individual quirks of having Mafia connections and a tendency to hit on Anything That Moves. She was featured prominently for a year or two, got a spotlight issue in 2002, and has since been reduced to mostly appearing in crowd scenes.
For about two years, 1996 to 1998, Delilah was an every-issue regular in Amazing Spider-Man. Being a Dark Action Girl and The Dragon to the Rose, a Non-Action Guy type of villain, she often got more screen time than any other villain. She was written out when she was drained by a vampire. She has since been used only in a couple of storylines as a henchwoman to nobodies.
The original Titans West from the '70s Teen Titans vanished when it came time for the New Teen Titans series, due to Marv Wolfman considering all of the characters (except Lilith and Beast Boy/Changeling) to be lame. Bumblebee and Mal Duncan (who were part of the original East Coast team towards the end of the '70s) were also Put on a Bus, and Duela Dent showed up once as a fat phony who revealed that she had lied about her origin of being Two-Face's daughter. After the Crisis, Wolfman seized the opportunity to retcon Bumblebee and Mal (now called "Herald") as having been part of Titans West, and attempted to erase Duela from continuity completely. Caveman G'narrk (who died in a Bus Crash Pre-Crisis) became a case of Death by Origin Story, while Bat-Girl (retconned to Flamebird) and Golden Eagle became even more shallow "joke" characters stuck in a rut of Can't Catch Up.
The earlier Titans all became demoted when it was time for Dan Jurgens' version of the Titans, partly due to Executive Meddling. Jurgens had originally planned to use Nightwing and the JSA member Wildcat as mentors for the team, but had to make do with using the de-aged Ray Palmer instead.
Characters like the second Wonder Girl suffered this in the change from Young Justice to the third volume of Teen Titans, as Geoff Johns decided to pay more attention to Robin and Superboy, effectively making the rest of the cast into wallpaper. After OYL, the focus then became Robin and Wonder Girl, which continued somewhat into Sean McKeever's run.
Happens with X-Men, even the main characters, as well as with other teams. It also happens with newer members (such as Marrow) who almost always turned out to be only temporarily popular or big-time.
The junior classes have it the worst. Out of the members who aren't Killed Off for Real, generally one out of each generation will get much of any face time if they aren't Wolverine's sidekick. New X-Men fans refer to this as 'becoming wallpaper'. Currently, Husk from Generation X and Pixie (who ironically started as wallpaper) from New X-Men are filling their respective generation's 'slot'.
This tends to be cyclical, particularly in the X-books. Jamie Madrox, for instance, started off as a background character with little personality, became an Ascended Extra in Peter David's first X-Factor run, then spent a couple years Not Quite Dead and about a decade as a bit player until David got the opportunity to have him lead the new X-Factor. The New Warriors (the ones who got blown up right before Civil War) started out as an attempt to ascend a bunch of nobodies and has-beens, with the whole team dropping Out of Focus several times.
A lot of human allies to the X-teams disappear when their creator leaves the books. Peter Corbeau got several particularly awesome scenes in Chris Claremont's early days, now, he doesn't even get an entry in the Official Handbook of the Marvel Universe.
Kitty Pryde inevitably gets reduced to a minor background character in adaptations. People often forget that, for a while, she was the closest thing that X-Men had to a central protagonist.
Comics have their own name for this trope: Comicbook Limbo. So many characters and whole teams end up there—even ones who used to have a series of their very own.
Cookie Dough, who was a core member of the team in the initial series, was removed for several stories and when reintroduced in the My Brave Pony: Star Fleet Magic III, was a minor character. The Deviant ART remake brings him back, not as a member, but as a recurring background character.
Krysta is acknowledged maybe once or twice in My Brave Pony: Star Fleet Magic III despite being the main character's best friend.
Stallionsof Harmony Verse does this to entire canon Mane6, being an AU story where Elements of Harmony are stallions from the show. To be precise, Prince Blueblood as Magic, Shining Armor as Loyalty, Big Macintosh as kindness, Soarin as Laughter, Thunderlane as Honesty and Doctor as Generosity.
Films — Animated
Finding Nemo: Gerald, the pelican who swallows Marlin and Dory, is onscreen for less than a minute, but was originally scripted with a notable role!
Master Shifu in Kung Fu Panda 2. He gets a couple of brief scenes at the start, then sends Po and the Five on their way while he remains in the Valley of Peace until the very end when he does a Big Damn Heroes bit. Justified in that his character arc was mostly done with by the end of the first movie and someone had to watch the Jade Palace. Thankfully averted with the Furious Five, who appear much more this time around, and all of them actively help Po out throughout the film.
In the Rankin/Bass animated version of The Return of the King, Legolas and Gimli are reduced to background characters who have a few non speaking cameos, while Saruman doesn't appear at all.
Faramir also crops up at the end. In a non-speaking moment with no explanation as to who he is. In order to give Éowyn a happy ending. The perils of Adaptation Distillation.
One notorious example is Ms. Brisby in The Secret of NIMH II: Timmy to the Rescue. While Brisby was the main protagonist of the first film, not only does the sequel avoid giving any mention of what she accomplished, let any role in the plot, she is on-screen for a grand total of 25 seconds, and only has two or three lines of dialogue.
Funnily enough, the Lorax in The Lorax. This is mostly due to the expansion of the present-day story about the Ascended Extra boy Ted, who is listening to the Once-ler's tale.
Zazu and the hyenas in The Lion King sequels (the latter don't even appear in the first sequel). Also arguably Nala, although she didn't have a ton to do in the first movie.
Fun fact for Frozen fans. The lead characters from The Snow Queen were named Gerda and Kai. So where are they in the movie? Why, they're servants to Anna and Elsa, of course!
The character of Pete, the largely silent and essentially background droog in A Clockwork Orange, played quite a pivotal role in the last chapter of Anthony Burgess's original novel. However, since Kubrick'sadaptation was based on a version of the book with the final chapter excised, Pete's role was rendered largely inconsequential.
A literal example. Isabelle Fuhrman had been cast in a small role in After Earth , but in the finished film, she is reduced to a split-second non-speaking appearance (when Kitai is told he is not being advanced).
Dan Murray, who played a large role in Clear and Present Danger and all Jack Ryan Sr. books after that, is killed in the Colomiban Cartel attack on the FBI Director, when in the book, he wasn't even there!
LAPD officer Sergeant Al Powell is a big part of Die Hard, but none of the other films take place in Los Angeles. The second film offers him a gratuitous cameo, and the rest leave him out all together. Possibly justified in that Al had a family and was working the beat again by the second movie, so he wouldn't have been able to join John for more adventures.
In the sixth installment of The Fast and the Furious series, Mia's role is downgraded so she can look after her and Brian's son. She only makes a few appearances early on and then isn't involved again until the climax when Owen Shawtakes her hostage.
Doctor Mindbender was more of an inversion. The character was never intended to have a name, and was only there as a plot device for The Doctor's path to darkness. After the fact, they realized he could easily be Mindbender and threw his name in for the fans.
Percy Weasley. He wasn't all that big a player in the books, usually being involved in the side-plots, but his estrangement from his family was a poignant reminder of what Dumbledore always said about Voldemort's gift for dividing loyalties. After the third movie, his only appearances consist of non-speaking cameos in Phoenix and Hallows, Part 2. Unless you watch the backgrounds, you wouldn't even notice he's there and is apparently still going through his book plotline, albeit almost entirely off-screen.
Up until Deathly Hallows, Charlie was mentioned a couple of times in the first film and Bill wasn't mentioned in the films at all. Bill and Charlie's only actual appearances in the first six films were in the photo of the Weasley family in Egypt, which was onscreen for about a second.
Tonks and Lupin only appear in one scene in Half-Blood Prince despite having a sub-plot in the book.
Mundungus Fletcher had a few minor roles in the books, but was completely ignored in the films until Deathly Hallows part 1, when he was required for the plot. Resulted in a bit of a shoehorning. Kreacher likewise had his role downplayed greatly, and since his introduction, got barely a cameo in Deathly Hallows. Both were still little more than extras for much of the series anyway, but its even more egregious in the films.
While Amy was one of the main characters in Honey, I Shrunk the Kids, in the sequel Honey, I Blew Up The Kid she only appears at the very beginning before taking off for college. The reason was the film wasn't originally supposed to be a sequel to HISTK. When the movie became a success, it was quickly reworked into one, but the original treatment didn't have roles for either Nick or Amy to fit into. Although Nick ultimately managed to still get a decent part, there really wasn't any room for her.
The Last Airbender naturally has this by virtue of trying to condense twenty episodes into two hours.
Momo shows up long enough to be introduced, then occasionally shows up in the background a couple times. You could be forgiven for not believing him to have followed Aang after the introduction.
Appa was also demoted. He doesn't get a lot of screen time and is more of a mode of transportation than an actual character.
Arguably, Katara and Sokka. Neither of them get many scenes in the spotlight, nor do anything of much importance, especially when compared to their TV show counterparts. It doesn't help that many of Katara's strong scenes are either given to Aang or cut entirely. At least Sokka gets his girlfriend.
Haru and Tyro... ahem, Earthbending Boy and his father.
Jet is the small boy Zuko calls over to regale the story of the banished prince.
There's also Avatar Roku, who was a major player in the Avatar's quest in the show. In the movie, with the exception of a brief mention, he's completely removed and his mentor role to Aang is handled by a dragon...for some reason.
Hakan and the alcoholics in Let the Right One In have significantly reduced roles in the film adaptation. They are removed entirely from the American version.
In The Lord of the Rings trilogy, perhaps the biggest casualty of this was Éomer, who was built up to be almost a Sixth Ranger to the trio of Aragorn, Legolas and Gimli in the book of The Two Towers. He was offscreen for much of The Two Towers movie as his role was merged with a minor commander who leads The Cavalry rescue at the fortress of Helm's Deep. Conversely, his sister Éowyn takes the almost-Sixth Ranger role since she also goes to Helm's Deep instead of leading civilians to another fortress. Their uncle King Théoden also takes his memorable lines and moments in The Two Towers and The Return of the King.
Also, Imrahil. In the books he's an important Gondorian commander and is the Acting Steward of Gondor while Faramir is healing. In the films he's shown a couple of times and it's not really made clear who he is.
In an in-universe example, this happens to a character in Mrs. Doubtfire. Early in the movie, Mr. Sprinkles is the star of a children's show. At the end of the movie, he's replaced by Mrs. Doubtfire and is demoted to Mr. Mailman, a minor character.
Done purposefully by the filmmakers and fandom of the Police Story/Supercop movies (combinations of Sequel First and Market-Based Title confuse the nomenclature.) Jackie Chan was the original star but one sequel (called Supercop in North America) featured Michelle Yeoh as a supporting character. She was so popular that the next movie (Supercop 2 in North America) featured her as the star, with Chan's character appearing only in a humorous cameo.
In the film of Queen of the Damned, Armand has two lines in total, and isn't even named as himself except by Word of God, though in the book he was a major player. Much of this is probably because Daniel Molloy was Adapted Out, and Armand's plot mostly revolved around Daniel.
In Scott Pilgrim vs. The World, Kim Pine, compared to her more involved role in the books (mostly because her backstory has been moved to the [adult swim]Animated Adaptation). Envy Adams gets quite a bit cut out as well, since her fight with Ramona is cut and is compacted into Ramona's fight with Roxy Richter. She is completely absent in the climax and her role is merged with Ramona's. Richter herself gets quite a bit cut out; she almost got a complete axing when Edgar Wright considered depositing Envy into her role as Ramona's 4th ex. Nega-Scott gets the axe from playing a pivotal role in the books to being reduced to a mere punchline in the movie. Lynette Guycott although having a minor but pivotal role gets barely minutes of screen time, and her punching the highlights out of Knives' hair was designated to Todd. Finally the Twins are almost cut out entirely, as they have zero lines (their actors don't speak English), zero backstory, and probably the least screen-time of any of the exes, only seemingly being in the movie because they are exes number 5 and 6 respectively.
In Serenity the characters of Book and Inara are set up as not living on the ship anymore. Shepherd Book is an odd example as he's only in two scenes in the entire movie (the second of which kills him off), less than any of the other main characters from the series. However, they're both really good scenes that play a major part in shaping Mal's own story arc as well as shedding some light on the film's villain, so despite his limited screentime he ends up being one of the more important characters.
Inspector Lestrade gets hit by this in Sherlock Holmes: Game of Shadows. He may not have been one of the most central characters in the first, but he still had a decent amount of scenes and relevance to the plot. In the second movie, he is entirely left out, only briefly appearing at the end with few lines. His sergeant gets about the same amount of screentime, though he had a number of scenes in the original film as well.
She was intended for a major role in The Undiscovered Country, but between casting difficulties and objections by Gene Roddenberry over an established character becoming a traitor, her name was simply used as a placeholder for Kim Catrall's character, Valeris.
Pretty much everyone in Star Trek: Nemesis except Picard and Data, but particularly egregious for Geordi, Dr. Crusher and Worf. All three do get additional scenes in the novelization, though.
Jar Jar Binks. Clearly set up in Phantom Menace as a Chewbacca for the prequels, he gets only a cursory nod in the sequel and a silent appearance in a group shot in the third. This was no doubt a result of fan backlash against the character.
In the original cut of A New Hope, Biggs Darklighter (this◊ X-wing pilot) had a much more prominent role. He's actually Luke's best friend from Tatooine who left to join the Imperial Navy, but the scenes where we learn this were deleted. In one scene, Luke meets him while on shore leave and he confesses that he's defecting to the Rebellion. In another, he and Luke get an emotional reunion before the attack on the Death Star, which makes his death in the battle a lot more tragic. The special edition restored his reunion scene with Luke, but left out the early scenes where we learn who he is.
Early versions of Return of the Jedi had a much larger part for the Death Star's commander, Moff Jerjerrod. In the shooting script, Jerjerrod is a high-ranking technocrat, taking orders directly from The Emperor behind Darth Vader's back. Jerjerrod butts heads with Vader over Luke Skywalker's capture and even has the guts to deny Vader passage into Emperor's Throne Room, leading Vader to strangle him near to death. Late, he reluctantly accepts orders from The Emperor to fire the Death Star on the Endor moon despite many Imperials still present there and even gives the order shortly before the station is destroyed. In the final cut, his biggest scene is greeting Vader's shuttle in the opening.
Lois Lane in Superman III shows up in the beginning, says she's going to Bermuda and disappears for most of the movie. Then she comes back before the movie's over as if nothing happened! This was largely done in retaliation after Margot Kidder criticized the producers for their decision to dismiss director Richard Donner from the franchise. It's a testament to how iconic the Superman mythos is in general, and Lois Lane in particular, that it wasn't worse.
Adrien Brody in The Thin Red Line. He was originally cast as the lead character and received second billing (though it was in alphabetical order except Sean Penn who was listed first) but only has a very breif and almost mute role in the released cut of the film. Brody learned about these changes from the original script at the premiere,after he'd already been doing press interviews about his lead role.
Captain Metropolis in Watchmen. In the book, he's a hopelessly naive superhero who forms the Crimebusters in the 1960s and tries to convince them that they can solve all of the world's problems. In the movie, Ozymandias forms the team (re-named "The Watchmen"). Metropolis becomes an unspeaking character who briefly appears in a flashback.
Rogue, as well, she had fairly large parts in the first and second movies, but her storyline in here remotes to her being jealous of Bobby and Kitty and taking an apparent cure. Part of it was also because Halle Berry didn't like Storm's comparatively smaller role and demanded a larger part. But objectively speaking they both were shafted.
Dr. Kavita Rao. Gets about thirty seconds of screen time, three lines in total, and then is Killed Off for Real. Most of her role from the comics (like holding the press conference) is taken over by Angel's dad. She was never a major character to begin with, and was a very recent creation when the movie was made, but still.
Psylocke, she usually has a fair amount of input on the plot in the comics.
Rogue only appears in a non-speaking cameo and doesn't even get a close-up. This is because all her other scenes were cut out and will be put on the DVD release.
Havok appears in the beginning to be rescued by Mystique and never shows up afterwards. Still, at least he survived unlike the rest of the First Class cast, with everyone who didn't appear in the earlier/canonically later films being unceremoniously killed off between films. But of course, he had to survive because in the film continuity he's probably Cyclops' father rather than his younger brother.
Storm does kick some serious ass, but gets little screen time overall and doesn't have many lines until midway into the movie. Justified as her part was diminished due to Halle Berry's pregnancy.
Compared to the prominence of her role in the comic version of Days of Future Past, Kitty Pryde's role is mostly being the means by which Wolverine gets into the past.
In Maleficent, the three fairies—major characters of the original and part of the driving force of the plot—are reduced to about four or five scenes, all of which involve them being incompetent. They don't even get to soften the curse—Maleficent does that herself as a cruel Hope Spot.
Prince Phillip suffers this as well. In the original, he was a Badass Prince who took up the entire second half of the movie. In this film, he gets two scenes and has none of his badassery in either of them.
Peta in the third Hunger Games book Mockingjay is in very little of the first half and doesn't really get any significant focus until the climax.
In Avalon: Web of Magic, The One Guy Zach appeared as a major character in the third book, at the end of which he seemed to be an important addition to the team. In books four to eleven, he's lucky if he gets a scene or two, or even a few lines of dialogue. However, the author says that he'll have a bigger role in the sequel trilogy, Shadow Warrior, so he may just be Out of Focus.
In James Gurney's Dinotopia, the first book centered around Arthur Denison and his teenaged son Will. When they split up towards the end, the narrative followed Will on his quest to become a skybax rider. The second book, The World Beneath, dropped the epistolary frame and went with Two Lines, No Waiting, showing what both did. The third, Journey to Chandra, has father and son meet in the beginning and briefly in the middle, but otherwise Will is a bit part. Orianna, a crucial character in the second book and hinted to be Arthur's Love Interest, has the briefest cameo in the third.
This happens to Ged in the Earthsea books. He's the main character of the first and third books (being the eponymous Wizard of Earthsea), and plays an important role in the second even though he's not its protagonist; but after he loses his power at the end of The Farthest Shore, he becomes a peripheral figure in Tehanu and The Other Wind, having given way to Tenar and Tehanu.
The Exile's Violin: In-universe example. When a battle between airships breaks out, Jacquie acknowledges that she is useless because she is neither a soldier nor a sailor. She watches the fighting as powerless to affect it as the audience.
Michael Grant has over 300 characters in Perdido Beach, and over 60 of them have names. So, while writing GONE , some characters are extras in some books, main characters in another and not even mentioned in others.
John Terrafino for example, went from being a minor character (GONE), a recurring character (HUNGER), a important/main character (LIES), a character who is eternally on mute and is only mentioned once in a cross refrence (PLAGUE) and then isn't present at all (FEAR).
The siren (or Jill) is a main character in LIES, but then is only mentioned in PLAGUE and FEAR.
Justin has a strange evolution. When first introduced in LIES, he's one of the main heroes, then, in PLAGUE he isn't present or even mentioned. Then in FEAR, he's back, but only as a recurring character. Making him, in effect, both a ascended extra and demoted to extra. In LIGHT, he gets a bridge dropped on him.
Colin Creevey had a moderate supporting role in the fourth and fifth books and then vanished entirely until Deathly Hallows, when in only one or two lines it is explained that he was killed by Death Eaters when Hogwarts was attacked. As a muggle-born (much less a sixth year), he wasn't even supposed to be there, but the author Handwaved this by saying that he broke into the school to fight.
"Mad-Eye" Moody and Dolores Umbridge both appear briefly in Half-Blood Prince but have no dialogue. Both were fairly major characters in previous books and have moderate supporting roles in Deathly Hallows.
Madam Hooch was never that important of a character in the first place, but after admiring Harry's Firebolt in Prisoner of Azkaban she is never even mentioned outside of Quidditch scenes and feasts.
For that matter, Quidditch itself drastically declines in importance after Prisoner of Azkaban, with Harry playing in a grand total of three matches in the final four books. No Cup is held during Goblet of Fire and Harry being kicked off the team in Order of the Phoenix. Even when Harry becomes Captain in the sixth book it's usually only mentioned for various character purposes, and once again Harry misses the final match.
Happened to most of the characters from the first series of Warrior Cats. Characters like Sandstorm, Mistyfoot, Cloudtail and Graystripe (who was also Put on a Bus for three books) don't make many appearances from the second series onward. Firestar still has a noteworthy presence as Clan leader, but he still isn't as important as the main characters. The second series characters were a bit better about this (except for Tawnypelt, whose purpose in the plot seems to be one of the few cats in ShadowClan who isn't a jerk, and to give birth to relatively important characters, and Stormfur, who has been Put on a Bustwice), especially with Leafpool, who is still an important character after the end of the second series.
In the first two Haruhi Suzumiya light novels, Haruhi was a walking, talking, reality-warping MacGuffin. Skipping ahead to the last few novels, and Haruhi seems to have been Put on a Bus. Koizumi says she's getting more normal, but we all know from the first few that he isn't exactly someone you'd trust too much. And everything comes from Kyon's point of view, and he's the poster child for Unreliable Narrator.
Partly due to the cast of thousands nature of the series this tends to happen to a lot of characters in the Honor Harrington novels, but a notable example is Aubrey Wanderman, who has a major plot thread running through the entire 6th book, but then vanishes bar a cameo afterwards.
Legacy of the Dragokin: Downplayed. Daniar used to be the hero but now she's one among many and has less screentime.
In the novel trilogy version of Mobile Suit Gundam, the Black Tri-Stars, the infamous Zeon ace trio who were known for their amazing teamwork on the battlefield, is only namedropped once, being mentioned as being the ones who captured General Revil. As well, Ramba Ral, who was well-known for his "This is no Zaku, boy!" line as he battled in the Gouf, doesn't even take part in the fights here, instead shown being worried for his mistress, who was working by Kycillia Zabi's side as a spy.
In the first Noob novel, Golgotha is introduced as Gaea's childhood friend and the guild's regular helper. In the following books, she's reduced to one or two token appearances and a mention that she's been helping the main characters "offscreen" during the Time Skip between installments.
In the original Pinocchio, the Blue Fairy had a much bigger role, being a mother figure and fulfilling the role of his conscience. In almost every adaptation, most of her actions are done by the cricket character. One adaptation didn't even have the Blue Fairy, the cricket almost completely taking her place.
P. G. Wodehouse was writing a standard-issue Boarding School serial about a kid named Mike when an eccentric supporting character stole the show...none other than Psmith. Unfortunately for Mike, the sequels Wodehouse ended up writing were dominated by Psmith and had very little to do with boarding school, so Mike stayed on as his sidekick and personal secretary, all but disappearing from the last two books.
The Dothraki that remain with Dany get quite a bit less page time as first her army expands and then she gets bogged down in Mereen in the third and fifth books.
Robb and Jaime only have one scene apiece in A Clash of Kings due to barely interacting with any POV characters. The TV series had to give them more to do.
By virtue of splitting A Feast for Crows and A Dance with Dragons by location instead of chronology, many characters do not appear at all in one book or another. However, Jon Snow and Samwell Tarly do appear briefly at the beginning of each others' plots in the respective books.
A moderate non-POV supporting character in the first three books, Lord Varys is absent from A Feast for Crows and only shows up in the epilogue of A Dance with Dragons. Certainly a memorable appearance though!
In the Star Wars Expanded Universe, this happened to Tahiri Veila for a while. During the latter part of the New Jedi Order, her arc was given a great deal of prominence and she was built up as a main character, but was barely an extra in the final book, and was a peripheral character during the Dark Nest Trilogy and the first half of Legacy of the Force. Then LOTF finally brought her back midway through.
King Draco features prominently in the first few chapters of White as Snow and later disappears from the book aside from being mentioned now and then.
Noob has a handful of characters whose main characteristic is to show up at quasi-random moments in the story. This works fine in the webseries and comics, but doesn't transfer well to the novel version's tendency for Extremely Short Time Span:
Golgotha: She sepends most of the first novel in company of the Noob guild, then gets single scenes in the following ones.
Dark Avenger: In webseries and comic, the guy who ends up in a complicated situation with Sparadrap due to being convinced that he's displaying Obfuscating Stupidity. Existence mentionned twice in the novels.
Tenshirock's presence is only really necessary for the third novel and he might as well not exist in the other ones.
Relic Tracker's guild is quite essential to the franchise-wide Wham Episode, but their purpose of being the Noob guild's Griefer is the only reason they are ever seen after that.
Arthéon gets a gradually diminishing role also, first by being kidnapped in Season 2 of the webseries, then due to Real Life Writes the Plot. This has resulted in his character being treated as a secondary role in the upcoming movie material.
Malin Berggren used to be the lead vocalist of Ace of Base for the first two studio albums, then got more and more into the background note This is to be understood quite literally in this case regarding the covers of the studio albums Flowers and Da Capo and the respective singles thereof. and her sister Jenny had to fill the void, and eventually quit the band (and her sister a few years later as well).
Mercury Rev flautist was credited as part of the guest orchestra from All Is Dream onwards. It was generous to credit her as a band member to begin with considering that she didn't play on every song and didn't appear with the band in interviews and photo shoots.
David Fridmann gradually phased himself out of the band, first declining to tour with them from 1995 onwards and then quitting as bass player before 2005's The Secret Migration while continuing to produce the band's albums. However, he remained credited as the band's bass player while still a studio player, making this case an aversion.
Alan Myers was the drummer for Devo up until the mid-eighties, after they recorded Shout. By that point Devo had made him somewhat obsolete on record, relying increasingly on drum machines rather than acoustic drums, so Myers left essentially out of creative boredom.
Roger Waters-I mean Pink Floyd did this to Richard Wright, as he was no longer a member of the band during The Wall but still played on that album. Their next album, The Final Cut, lacked him altogether. David Gilmour brought him back, but still as an extra on the first Waters-less album A Momentary Lapse of Reason. Then The Division Bell (the final album of the band) credited Wright as a band member again.
Before that, the band did this to Syd Barrett, due to his drug use causing increasingly erratic behavior. He only appears on a few tracks on their second album.
Keyboardist Ian Stewart was an original member of The Rolling Stones, but when they began recording in 1963 their manager, Andrew "Loog" Oldham, had him officially demoted to road manager, mainly because his straitlaced, short-haired look didn't fit the image Oldham was trying to cultivate for the band. Because the band still liked him, Stewart did continue to appear on the Stones' recordings, though, and occasionally performed with them on stage until his death and was inducted with the rest of the band into the Rock and Roll Hall of Fame in 1989. He - by any meaningful measure - was still a full member of the band, so his demotion really only was relevant in promotional material.
A lot of early Rock & Roll and classic rock hits, especially from the British Invasion, were covers of old Blues songs. The similarities are so close, Sam Phillips famously said "Rock & Roll is just the Blues sped up."
Hip-Hop DJ's; while still prominent on tours and the mix-tape circuit they have all but disappeared from mainstream media. In fact a cynic could say the same thing about all of the other "pillars of hip-hop".
This eventually happened to Cutter John in Bloom County. Though he didn't disappear like the scores of other characters who were dropped from the comic, his role was dramatically reduced by the strip's end (Word of God being that wheelchairs are difficult to draw within the confines of a comic strip panel).
After the attacks on New York and the Pentagon, Boondocks became less of a life comedy strip and commented more on world news. It takes few to commentate so the strip neglected everyone except Huey, Riley, Granddad, Tom and Caesar. Eventually a few characters were brought back though, Jazmin was mad that Huey wasn't worried about her while she was gone.
The London Evening Standard used to run a cartoon called Clive about a boy of 17-18 and his various escapades. However, the strip began focusing less on him and more on his ten-year-old sister Augusta, until he was such a minor character that the strip was renamed Augusta. It was recognisably the same strip, especially since it still had all the Running Gags of its previous incarnation.
Dilbert 's transition from slice of life absurdism to office satire meant the more fantastical characters were marginalized (Ratbert, Bob the Dinosaur, Phil the Prince of Insufficient Light) if not eliminated altogether (Zimbu the Monkey, Dawn and Rex). There's also Mordac the Preventer of Information Services, who went from a regular recurring villain to appearing infrequently.
On The Fastrack used to star Bob Shirt, but compared to the other characters, he was boring. For many years now, he has appeared almost exclusively in ensembles — the only exception being him complaining about his reduced role at Fastrack. Another Bill Holbrook comic, Safe Havens, used to star Matt Havens. He hasn't appeared at all in the last decade.
Luann was initially a comic largely about the titular character and her classmates and family. Once Brad, her brother, started becoming more and more important to the strip, gaining his own storylines, most of the teenage cast was downgraded significantly. Even Luann's best friends Bernice and Delta rarely appear, to say nothing of poor Knute and Crystal, themselves Satellite Characters of others.
They seem to have moved into a pattern: Brad and Luann alternate focus each week. Luann's storylines tend to alternate between using her parents and using her friends. Every other month we usually get a week focusing on Gunther and Knute.
This happens all the time in Newspaper Comics - the long running American strip Nancy was initially based around the title character's aunt Fritzi (the original title was Fritzi Ritz).
This happened to a number of Peanuts characters: Shermy, Patty, Violet, Freida, Pig-Pen. For example, in the 1980's and 1990's, Patty (not to be confused with the more prominent Peppermint Patty) appeared in a total of three comic strips. Word of God said Patty and Violet got the shaft because Lucy worked better as a female bully character, so it would be too redundant to have all three of them featured prominently.
In the latter half of the 1990s this had happened to nearly the entire cast. By the end of the strip's run, the focus had boiled down to four major storylines: the misadventures of Rerun (with Snoopy or Lucy acting as the Straight Man depending on the plot), the day-to-day life of Snoopy's desert-dwelling brother Spike, the travels of Snoopy's other brothers Andy and Olaf, and Charlie Brown and Franklin (who had essentially replaced Linus) talking about life while leaning on a brick wall. Charlie Brown's sister Sally would occasionally get her own Sunday strip, but the other characters (particularly Schroeder, Peppermint Patty, Marcie, and the already-mentioned Linus) rarely appeared.
Retail had a shake up in 2012 where Stuart, the store manager, was promoted to district manager, with his assistant Marla taking over his old spot. While Stuart still shows up, he doesn't appear as frequently these days.
Once upon a time, back in 1919, there was a comic called "Take Barney Google f'rinstance". The titular character was a diminutive gambler with a gigantic angry wife. The wife was written out, and Barney got himself a horse named Spark plug, and the strip was renamed "Barney Google and Spark Plug". In 1934, Barney found himself deep in the Appalachians, where he met a hill-billy named "Snuffy Smith". And the strip was renamed, again, "Barney Google and Snuffy Smith". Here Barney would live for 20 years, until he left in 1954... But the comic stayed with Snuffy, and Barney became a rare guest in the comic carrying his name, his last two appearances being in 1997 and 2012.
During development of Terminator 2: Judgment Day, pre-release secrecy and fears the pinball could be released before the film resulted in the near-total removal of Robert Patrick and the T-1000 from the playfield or the backglassnote except for a small picture on a light shield. When the dot-matrix display programming was nearly completed, the "liquid metal" T-1000 was public knowledge, which allowed him to be included in the display animations.
Both played straight and inverted by The Acolytes. Ron "Faarooq" Simmons was the first African-American WCW World Heavyweight Champion and had one of the longest single reigns of the title (at 150 days). In the WWF, he became famous for leading the stable "The Nation of Domination," which was also responsible for jump starting the careers of Mark Henry, D'Lo Brown, and most famously, The Rock. After the Nation disbanded, he found success in the Acolytes (later the Acolytes Protection Agency, or the APA for short) with John Bradshaw Layfield, who had several failed singles pushes beforehand. After the APA split up, Layfield, now better known by his initials JBL, became a world champion with the Intercontinental, United States, and WWE Championships, while at the same time Simmons was reduced to making short cameos watching backstage promos and saying "DAMN!" It is of course worth noting the 9 year age gap between the pair.
Happen to many WCW wrestlers who joined up with the WWF/WWE following the closing of WCW. Save for Rey Mysterio, and to a lesser degree Booker T, none of them managed to find much success in the WWE. In fact, Booker T himself also happens to be a pretty egregious example since he went from being one of the top wrestlers near the end of WCW, to not receiving a decent push in the WWE for about 5 years despite being very over with the fans. Some believe Booker was robbed at WrestleMania XIX and should have won the title from HHH.
The Pro Wrestling industry term for this trope is "getting buried." It refers to the worked lowering (relegation) of a popular wrestler's status in the eyes of the fans. It is the act of a promoter or booker causing a wrestler to lose popularity by forcing him to lose in squash matches, continuously, and/or participate in unentertaining or degrading storylines. It can be a form of punishment for real-life backstage disagreements or feuds between the wrestler and the booker, the wrestler falling out of favor with the company, or the wrestler receiving an unpopular gimmick that causes him to lose credibility regardless of win-loss record. It is also a result of a company seeing a wrestler as having no potential or charisma. The term can also be applied to a wrestling company that jumps the shark, rapidly loses ratings, fans, and finally becomes bankrupt. According to many critics, the most infamous burial of a company was The Fingerpoke Of Doom, a pivotal incident in the Monday Night Wars that took place during a Hulk Hogan/Kevin Nash match on January 4, 1999 on WCW Monday Nitro at the Georgia Dome.
This also happens to some wrestlers towards the end of their careers. They get older and/or less interesting, but still have enough respect from the company that they aren't flat out fired. Instead they slide down the card to mainly work on the opening matches and put the new guys over. Tito Santana and Val Venis are two of the best examples of this. At his high point Venis was an upper midcarder who actually tested the main event waters by feuding with Mick Foley, but he spent the last 4 years of his career in WWE working opening matches, working Heat, and rarely winning.
Tony Garea, who held the WWE World Tag Team Titles on five occasions in the 1970s through early 1980s, was a jobber-to-the-stars (that is, a wrestler who still gets occasional wins over low-tier stars and jobbers, but consistently loses to mid- and top-card wrestlers) late in his career. Part of this was he used his position to help assess the skills of newly arrived heel wrestlers. Today, Garea remains with what is now World Wrestling Entertainment as one of the company's top agents.
This happens to many women's wrestlers, especially after their Playboy pictorials come out and everybody's already seen them naked. Torrie Wilson suffered a very painful decline from "Top Tier" star to "Still on TV Every week" star to "In a stable" star to "maybe shows up on TV every once in a while" star. Candice Michelle and Maria Kanellis have similarly been released. Non-pictorial-related Divas include Victoria, who went from top-tier WWE Women's Champion to a jobber to new girls before quitting. Molly Holly had all but vanished by the time she requested her release. Most recently, WWE Divas such as Kelly Kelly, Beth Phoenix, and Layla have been recently relegated to competing on the C ShowWWE Superstars in favor of their male counterparts such as John Cena, CM Punk, Triple H, Alberto Del Rio, Randy Orton, Cody Rhodes, and Sheamus.
This has been happening quite frequently to many of WWE's mid-card talents with WWE's increased use of part-time talent starting in the early 2010s. Full time wrestlers who spend most of the year on the mid-card or upper mid-card (bordering on "main event status,") will usually get demoted down the card when it comes time for The Undertaker, Brock Lesnar, the Rock, Triple H and the like to make their semi-annual returns for a few weeks or months to dominate the scene (usually in the weeks heading into WrestleMania, SummerSlam, the Survivor Series, and the Royal Rumble). Some of the most frequent victims include Cody Rhodes, Kofi Kingston, Wade Barrett, The Miz, and more recently Damien Sandow. In addition, even wrestlers such as CM Punk and Daniel Bryan will go from the main event level to the mid-card when overshadowed by the returning greats.
After the untimely deaths of Jim Henson and Richard Hunt, most of The Muppets they once played were handed down to new performers, starting with The Muppet Christmas Carol. However, Henson's Rowlf and Dr. Teeth and Hunt's Janice and Scooter, all formerly major characters with sizable roles in previous Muppet productions, would be reduced to non-speaking background appearances or not appear at all. The Muppets reversed this, as all four characters were as prominent as ever in the various trailers and the film itself.
The priest who plays a minor part in The Most Happy Fella played a considerably larger role in They Knew What They Wanted. Whereas in The Most Happy Fella he silently approves of Tony's resolution to have "plenty bambini" by his wife-to-be, in They Knew What They Wanted he objects strenuously to Tony taking a non-Catholic wife, in return to which Tony accuses the Church of coveting his inheritance.
Benvolio doesn't appear in the last two acts of Romeo and Juliet, despite having been quite important in the first three. He doesn't even show up to cry over his dead cousin.
Mary Jane and Aunt May's only appearance in The Amazing Adventures of Spider-Man is over a voice mail message that can be heard in Peter's office, which you can only walk through if you're going through the Universal Express queue line.
BIONICLE has many examples, even after its Merchandise-Driven nature has faded. For instance, the Turaga: major side characters initially with a great story-importance, then got two full years devoted to their early lives, but from '06 onwards, they barely appeared in any scenes, and now... Where are they?
Similarly, Kano and Minagi in AIR. Everything from merchandise to posters to, well, the backstory of the game makes it clear that this is Misuzu's story. Therefore, their routes are just there so the game can't be accused of having no variety — and when you think about it, if either of them wins, then the incarnations of Kanna will live and die in loneliness and pain for all eternity (especially with Kano's "good" ending). They were completely removed from the movie adaptation, and their arcs were shrunk to three episodes each in the Kyoto Animation version. They do each have one good figure, though. One.
From the original CLANNAD game we have Yukine, who, much like poor Sacchin, was originally planned to be one of the main heroines.
And in After Story, anyone whose last name isn't Okazaki or Furukawa gets shafted in terms of the spotlight halfway.
Also Kappei. He was a pretty important character in the original visual novel, but never appears in the anime, EVER.
Assassin, Shinji and Zouken in Fate/hollow ataraxia get much smaller roles than they did in Fate/stay night. Well, Assassin had a small role anyway. The latter two probably get smaller roles because the game as a whole is lighter in tone and they were two of the darkest characters.
Good luck finding a decent Shiori figure from Kanon. At least Kyoto Animation did her arc justice, and her falling out of the public eye might be because she doesn't have a "seven years ago" connection and is just a normal Ill Girl. In the 2002 anime, she, Makoto and Mai all fell victim to this, having their arcs squished into one episode each with key portions removed.
Satsuki Yumizuka a.k.a. "Sacchin" from Tsukihime. She quickly disappears on each route of the game despite being set up as another possible heroine, and in some branches she is quickly and cruelly dispatched by Shiki Tohno after becoming a vampire and declaring her admiration for him in a truly Tear Jerker moment. The anime lets her survive unvampirized, but other than that it didn't treat her much better; the manga, more of the same.
In Melty Blood she re-appears, but as an enemy, in her vampire form. She is quite real (and dangerous) in the game, but in its manga adaptation she is the form that Tatari took after discovering Shiki's guilt for having had to kill her, and then he has to dispatche her again.
She is more famous for how she doesn't appear that much on the other semi-official games, and the unreleased "Satsuki route" (which was supposedly planned and written but cut out, and is allegedly the one where the events of Melty Blood happen) is one of the running jokes of the franchise and the fandom. Within some fandoms (including this very wiki; see Meta below) she became the poster girl of the phenomenon (and former Trope Namer for this very trope) due to a meme based on the phrase "Isn't it sad, Satsuki."
Satsuki may finally catch a break in the updated remake, which is all but confirmed to feature her long lost route, and with it, a chance at not being fatally stabbed by her love interest.
By season four of Ansem Retort, Marluxia is demoted so much he's left behind with Darth Maul while the rest of the cast members take Red XIII with them to Hawaii. This is one of the reasons he's so keen on fighting Xemnas in season six: he gets more screen time that way.
He seems to be re-ascending in the current season: he's one of four people traveling through time to stop Xemnas. (Apparently, Axel and Zex need him to drink the time-traveling gay drinks. Because he's gay.It Makes Sense in Context.)
Justin and Sarah in El Goonish Shive have steadily sunken into the background, though Dan is trying to avert this. Specifically, Justin seems to only exist to be a gay male and Sarah as Elliot's girlfriend.
Justin, at least, was a major focus in the "New and Old Flames" arc.
Sarah is getting more "screen" time and more of her own role as Tedd's lab assistant in one of the current arcs relating to summer jobs.
In Homestuck, this happens to several characters after they get killed. They then recognize that this is happening, and one makes it their mission to become relevant again (dragging a friend along for the ride whether he wants to get back into the spotlight or not).
In Jayden and Crusader the character Hannah has often slipped into the background and mostly only exists to give Smic another character to bounce ideas off of, a roll that could be accomplished by a lamppost.
In Least I Could Do, Rayne's best friend John was given a rather strong demotion as writers switched over, being replaced with a long lost best friend. He began to see a resurgence in later times, though. Supposedly, this is because he was based on the writer's real best friend, who he had a falling out with.
Happened to the human children in Noblesse some time after the Parachute Trio of enhanced humans formed. This is not the case in the Noblesse S lite novels.
Stephan used to be a much bigger part of Ozy and Millie. The cartoonist explains that he was created to represent the overly confident geeks of the dotcom era; when the dotcom bubble burst, there simply wasn't as much of a place for Stephan.
Several characters in Questionable Content, most notably Steve (Marten's best friend, now rarely shown) and Raven (who's apparently off getting her degree). Seems like Penelope is sliding into that abyss as well. Of course, none of them have had the indignity of being eaten by an Allosaurus.
Steve seems to have returned, and appears far more frequently than before, although still very much a secondary character. Pintsize and Winslow, on the other hand, seem to be slipping towards this with their ever decreasing appearances.
When Penelope and Cosette weren't seen for awhile, the author lampshaded it by saying they were "just to the right" and off camera.
It's happened a few times in Real Life Comics. Officially, this list includes Danny, Crystal, and the first Liz. However, anyone but Pal and Alan Extra under the Supporting Characters section get precious little panel exposure. In fact, it doesn't appear that Debbie or Cliff have appeared in the comic for years.
This is actually lampshaded in this strip where it's questioned if anyone remembers Ben at all
Recently Debbie returned... revealing that she had been stuck in a terrible limbo between life and death for the proceeding decade.
Rachel and Tessa start off Scary Go Round as the main protagonists, but after the first chapter they're demoted to the supporting cast. The comic would often spend time focusing on some characters at the expense of others before rotating back, but they never really recover: it's another six chapters and nearly a year later before they get the limelight back. After that, they make another few appearances, but they're inexorably sliding towards a Face-Heel Turn and finally being Put On A Bus Toheck.
Dr. Lorna hasn't had more than the (very) occasional reference in Sluggy Freelance for years, despite being Riff's mom and still living in the same town by all accounts. She's essentially been Put on a Bus, having disowned Riff and fired Gwynn and Zoe, leaving her with no connections to the cast (and satirizing Dr. Laura no longer being in style).
Happens to several characters in Something Positive, but the most notable example is probably Monette. After years of being a major focus in the Texas storylines, she's Put on a Bus to California and has shown up sparingly since. Arguably significant to her Character Development, but her drop in panel-time is very noticeable.
Randy specifically sets aside time at the beginning of every year to show characters that are out of focus — calling it "Old Familiar Faces." So these characters are more properly Commuting on a Bus. But yes, if you aren't interacting regularly with Davan, Aubrey, PeeJee, Jason, or to a lesser extent, Mike, you just aren't in the comic. Especially odd is the absence of Davan's disabled sister Dahlia, who lives close to the Texas cast and wouls seem to need her brother's help and support.
The title character of the notorious Sonichu series takes a backseat to everyone else in the comic after issue #1, which begins to center completely around Chris. He does gain some more attention in Episode 8 and onward, but it's not much.
Mr. Birdbeak from Tragic Deaths. In the first three comics that that Petalklunk made, he was the main focus, but now he's only made one appearance after it switched focus to the war between Petalklunk and Mr. Bignose.
Endemic to Sam and Fuzzy. The comic is based into arcs separated by month- if not year-long Time Skips, bringing with them a severe disruption of the status quo. Characters like Lance, Alexa, Ackerman, Carlyle, Malcolm, Earl and Sidney, who were frequently appearing characters in the arcs that introduce them, later move on and away and appear sparingly if at all.
Rowby from The Bug Pond was featured in some of the earlier comics and was even given a bio on the character page but hasn't done anything of significance since.
Iridescence and Doodlecute don't do much but stand around in Dusk's Dawn, despite being in an ensemble cast. Meanwhile:
Mister Brave saves Star Whistle from the magic ring.
As with Comic Book Limbo, both players and entire campaigns came and went over the course of the ten-year history of the Global Guardians PBEM Universe. As they did, most of the characters involved would fade from being important main characters to being supporting NPCs to eventually being background color.
Thanks to having Loads and Loads of Characters, this happens frequently in the Homestar Runner world. Inexplicably, Pom Pom (one of the original main characters) did not appear in the season finale of Strong Bad's game, despite Pom Pom being in every other episode up to that point. In fact, Pom Pom used to be one of the three main characters along with Homestar and Strong Bad, although now, his appearances are rare, and the annual Christmas/Halloween cartoons are the only times he'll be seen consistently.
The Poopsmith's demotion is, if possible, even more evident than Pom Pom's, as the Halloween cartoons just might be the only time he's seen at all anymore (evidently a result of the two characters being silent and bubbly-voiced). Still, he didn't do too bad considering he was an Ascended Extra to begin with.
Like Pom Pom, Homsar also didn't appear in the finale for Strong Bad's game—but he, like the Poopsmith, started out as an Ascended Extra (from a Strong Bad E-mail, no less!) and even then he was often relegated to clickable Easter Eggs.
Handsome Tom also had this happen to him, relegated mostly to posing as Kickassia's flagpole. This was lampshaded in one of the "making of" videos, where Doug passes out the script and apologizes to Tom for having him be "an object". Tom takes it pretty well, pointing out that objects are useful. The other contributors have also said that Tom's okay being in the background because he doesn't think he's an especially good actor and is there mostly to have fun.
Similarly, Linkara is MIA for most of the story, but the actor is prominent as Linkara's villainous robot double.
Andy had this happen to him in Season 2 of Omega Guardians having gone from a character with a huge role in Season 1's plot to sitting on the sidelines with random appearances here and there.
Sister from Red vs. Blue. She brought the ship to Blood Gulch, and her arrival leads to the Reds discovering the underground caves. After that, she gets shuffled around from the Red team to the Blue team and finally to just bumming around with Doc, by which time she's barely seen. She appeared once or twice in season 6 and has not been seen since.
Sister suffered from all her personality traits being stuff that could not be done though machinma by Roosterteeth at the time. Anytime she is doing something, she ends up being off screen while the other characters comment on it, and that only goes so far.
Wyoming also suffered this. In the Blood Gulch episodes, he was one of the primary villains, alongside O'Malley; oftentimes accomplishing his objectives. But despite his role in those episodes, he is rather unimportant in the prequel portions of Seasons 9 and 10. Word of God is that this is due to his goofier personality clashing with the more serious tone the Freelancer bits have.
Apple has done this to its Mac products with the success of the iPad and iPhone.
Almost every US President ever after their term. In office, they're the most well known person in America but once their term is up, they sink to the background except for a few public appearances here and there. The one exception was William Howard Taft, who after leaving office was appointed Chief Justice of the Supreme Court, an extremely powerful position in its own right.
The same could be said for any nation's leaders. They're the most important person while they're in power, but then disappear into the background after they lose power. It's pretty rare for a former leader to zig-zag between this and Ascended Extra, though for nations that lack strict term limits the possibility always exists. (Australia is probably one of the few countries where examples of this exist, with three Prime Ministers having done this during their lives in parliament.)
Cabinet-level positions occasionally avert this. Usually a party will be in power for a given period, be replaced by their rivals, then come back to power a decade or so later. When that happens, ministers / secretaries who served in government the first time sometimes come back when their party returns to office.
After the Virtual Boy flopped, Gunpei Yokoi was given what amounted to a desk job and had no real power. He would later leave Nintendo entirely.
Pluto. It got its own spin off, Solar System: The Dwarf Planets Saga. Much earlier, Ceres became the newest member of the Solar System, but, an influx of other similar characters (Pallas, Juno, Vesta) led for them all to be dropped. Ceres, luckily, got a role in the Dwarf Planets Saga alongside Pluto.
Happened to dinosaurs: for a hundred millions years, they were the dominant animals on land. Now that mammals and humans in particular have taken over, what remains of them? Birds... Although it hasn't been too bad for them since there are about 10,000 bird species compared to only about 4,000 species of mammals.
Reptiles, as a whole, exemplify this trope even if they still play a big role in our ecosystem. Long ago, they ruled the Earth for more than 185 million years during the Mesozoic Era (compare the Cenozoic Era, which is barely a third in length) and were very diverse in their respective area. Some scientists believe that if the K-T extinction event never happened, the smaller theropods might have achieved an intelligence similar to humans.
The same might be said about synapsids (or "mammal like" reptiles that preceded dinosaurs as dominant terrestrial vertebrates. After Permian-Triassic mass extinctions, the only traces left of their descendants were tiny rat-like creatures that slithered in the shadows, while the ancestral archosaurs (ancestors of dinosaurs, among other things) became dominant.
In a manner of speaking, when a company, government entity or school district purchases new vehicles, the new vehicles are the ones used on the primary routes and/or long trips. The older vehicles are demoted to shorter routes, while the oldest vehicles in the fleet are parked in the yard and used as spare vehicles (such as when one of the newer vehicles is unavailable or in the shop for repairs). Eventually, it is the oldest vehicles that are sold off and replaced by the new vehicles, and the cycle continues.
An illustration: A school district in a rural school district covering 200 square miles purchases five new buses. The new buses are placed on the high-mileage routes and used for athletic trips. The buses they replace are then put on shorter routes, perhaps in-town. The oldest buses still on regular routes are then parked at the bus garage, used only when one of the newer buses is being repaired or otherwise unavailable. To mean – as a bus gets older, they begin fitting the trope more and more as the newer buses fit the spotlight.
The same thing happens on the railways, especially with passenger engines. The railway gets a new passenger engine, the fastest thing on the rails, and it pulls the big expresses for about ten or fifteen years. Then it gets an even newer engine, and the original one gets put on the second-string trains. Finally, after thirty or forty years in service, the former "star" engine is clanking around on branch lines or commuter routes before it gets scrapped or donated to a museum. Ditto for airlines.
And also for cruise ships — the newest ships get the most prominent (often longer) routes, while the older ones run less popular or shorter routes, and the oldest ships doing 3-day runs to the Bahamasnote (from Florida or other US East Coast ports) until they are sold off or scrapped.
In the West, advances in agriculture that made meat more widely available did this to vegetables. In Western cuisine, meat is considered the "main dish" with vegetables as "sides". Due to the health problems excessive meat consumption can cause, many experts are recommending that meat should be Demoted To Extra.
Mergers in general. As the big boys get bigger and bigger, even the moderately-sized regional companies in the same market are either shunted aside or gobbled up by the bigs. Wal-Mart and Target v. K-Mart is a good example.
Most of the world's remaining monarchies are now constitutional monarchies within a parliamentary system. In such cases, the real power resides in the Parliament (and in the person of the Prime Minister.) The monarch's position becomes largely ceremonial. Even in cases where the constitutional monarch has considerable residual or theoretical power (e.g., Great Britain), the power is seldom exercised.
Speaking of Parliament, the institution itself was originally a threefold system with the 'King-in-Parliament', the House of Lords to represent the aristocracy, and the House of Commons to represent the wealthy middle classes (the idea that poor people might actually have a right to representation didn't have much traction at this point). From the Civil War onwards, the monarch was gradually removed from this arrangement, leaving the Lords as the main centre of power. However, from the early 19th century onwards they too began to lose power, and its aristocratic nature was also reduced. Now the Commons holds supreme power and the House of Lords is just a technocratic advisory body.
This even happens to some countries in the course of history.
Iran (known for most of history as Persia) was regarded as the first world empire (under the Achaemenid Dynasty), when it conquered most of what was then called the "civilized world". It remained a major power even after the Arab conquest. Now? Just a third-world theocratic despotism.
Spain and Portugal used to be major world colonial empires during the Age of Exploration. By the late 19th century, they became less mighty.
The Dutch used to be a world power. Sic transit gloria mundi.
Ottoman Empire; it seized half of the middle east and some eastern European countries but after WWI, Ottoman Empire fell and a fresh Turkey was born. With Turkey's desperate attempts in becoming an EU member, it's obviously lost its relevancy.
Germany and Japan used to be major world military powers in the first half of the 20th century. America used to think that they would conquer the world by buying it. Later they just follow their much more powerful allies.
Your colleagues from school/highschool/university/work/volunteering. While it's likely a few of them will remain lifelong friends, the others will, at best, be reduced to an occasional chat when you meet them by accident on the street. Even with the advent of social networking sites it's unlikely you'll spend any significant amount of time talking to most of them.
Your parents. When you're a kid, they are the most important people in your life. However, as you get older and have a spouse, children, friends, co-workers, employers, and the like, your parents eventually become secondary or even tertiary people in your life. This varies by culture; there are some where even after the child grows up and gets married, his or her parents remain very much a big part of their lives (and are culturally expected to remain so), especially when they live close by.
Also your ex-girlfriends/boyfriends/husbands/wives/friends. Even if you remain on friendly terms, chances are you won't see them nearly as often after the break-up. There are a few cases where former lovers become best friends, but they are rare.
With the advent of Social Media, unfriending, unfollowing and, the biggest demotion, blocking. Definitely counts as a "demotion".
You also "grow out of" forums/other social media servicess and go from spending an entire weekend on somewhere to forgetting it exists or simply, only posting rarely...Both going from extremes of frequency to infrequent or nothing.
Back in the days when MySpace was the dominant social media site, the choices for your Top 8 Friends (prior to the expansion into however many you wished to list) showed just who had been demoted (in their own minds, at least).
Also happens when you have a fight/fall out with a friend or just stop getting messages/calls from someone. Moving away is another example...
Satsuki from Tsukihime is the center of the meme "Isn't it Sad, Sacchin". What makes Satsuki's lucklessness worth a section here, is that it even extends here, on TV Tropes. This trope was originally named "Isn't It Sad", after the meme in question. With the wiki's shift to less esoteric titles, Sacchin was—you guessed it—demoted in importance once again. She has since been demoted again; for a while, she was still the page's image, but she's since been replaced. Really, the only reason this page isn't a Self-Demonstrating Article is because putting it on the appropriate indexwould be a Promotion FROM Extra.
When a character-named trope has its name changed here on TV Tropes, it can end up demoting that character from star to being just another example. For instance, Spike is now just one more instance of Badass Decay instead of being the defining instance of "Spikeification". Nor let us forget Wesley Crusher, former tropenamer for Creator's Pet.