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%%The individual medium sections are alphabetized with the exception of Genre-Specific entries. Please place examples in alphabetical order within their respective medium/sport.
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Hail to the LongRunner, the show that stands the test of time. But not all Long Runners pass that test unscathed. Actors [[AuthorExistenceFailure die]], [[RoleEndingMisdemeanor or get fired]], or [[MoneyDearBoy lose a contract dispute]], or retire, or simply don't want to play the same role for the rest of their foreseeable career, or are concerned about being TypeCast, or don't want to deal with the costars of that series anymore. But creators and executives don't want to let their CashCowFranchise or treasured premise go so easily. Alternately, often the inverse is true, and shows often become Long Runners due to allowing cast turn over. So the show continues with replacement cast members...and so occasionally you get shows where the show's main cast hardly resembles the original. Nearly all of the above can apply to characters in Literature and other works without human actors, if the series spans enough time InUniverse and/or [[AnyoneCanDie has a high turnover]].

To qualify for this, a significant percentage of the work's ''main cast'', including recurring, named supporting cast, has to change. {{Red Shirt}}s, extras and guest stars don't count. A one man show only needs the one person to change, but that won't cut it for an EnsembleCast. Essentially, either SuspiciouslySimilarSubstitute or TheOtherDarrin, ''en masse''. (Though it ''can'' be spread out over time.)

Having a lot of turnover is by itself [[TropesAreNotBad a neutral phenomenon]], but for many people, it's a cause to believe a show has JumpedTheShark, is DarthWiki/RuinedForever or is a FranchiseZombie, especially if the departing cast were a main reason for the show's appeal to them. Conversely, the incoming cast may find themselves working [[FinalSeasonCasting for only one season anyway]].

Aversions of this Trope in music are covered under LongRunnerLineUp.

See also RevolvingDoorCasting for shows that have a high cast turnover '''without''' running for a very long time.
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!!Examples:

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[[folder: Animation in General]]
* ''WesternAnimation/{{Ben 10}}'' had a TimeSkip aging up the main and recurring kid characters. ''In addition,'' it was decided that Creator/DeeBradleyBaker should voice ''all'' of Ben's aliens, then later the crew decided "nah, give the guy a break." The result is many characters (and alternate forms of characters) having ''three'' actors, even when actor availability isn't an issue.
* The ''Anime/{{Pokemon}}'' Anime characters ''themselves'' also qualify: Outside of Ash, Pikachu, and [[TerribleTrio Team Rocket]], only Brock has been a co-star in multiple regions and even he is currently inactive. The InexplicablyIdenticalIndividuals don't count.
* The eighth season of ''WesternAnimation/TeenageMutantNinjaTurtles1987'' did away with Irma, Casey Jones, Mondo Gecko, the Punk Frogs, the Neutrinos, Leatherhead, Baxter, Groundchuck, and Dirtbag, in favor of new characters like Titanus. The ninth season eliminated the newbies from season 8 as well as the Rat King, replaced Shredder and Krang with Dregg, and Bebop and Rocksteady with Hi-Tech. April was replaced with Carter. IN the tenth season, April came back to replace Carter. Hi-Tech was replaced with Mung.
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[[folder:Film]]
* The Film/JamesBond film series has four major recurring roles: Bond, M, Q, and Miss Moneypenny. Eighteen actors[[note]]Counting [[Film/DrNo Peter Burton's Major Boothroyd]] as Q and Creator/RalphFiennes, who becomes M at the end of ''Film/{{Skyfall}}''[[/note]] have played these roles over the twenty-three official movies.
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[[folder:LiveActionTV]]
!!!Genres and Production Blocks
* Most {{Soap Opera}}s are run on this trope. Since many have been running 40+ years, and people don't want to spend the entirety of their lives on one show, they tend to leave the soap after a few years to pursue alternative employment options. To replace them, either the [[TheOtherDarrin character actors are changed]] or new characters are brought in. This means that the main casts of soaps tend to change drastically every few years. As an example, New Zealand-produced soap opera ''ShortlandStreet'' first aired in 1992, and as of 2011 only one of the original cast members remains (Dr Chris Warner).
* Creator/{{NBC}}'s Late Night block has gone through this a bunch of times:
** ''Series/TheTonightShow'' has gone through at least five different hosts, all of whom brought in their own people to run the show in a new direction. The only exception may be when Jay Leno was brought back to the show in 2010.
** ''LateNight'' has gone through a similar situation but with only three hosts - four if you count its predecessor, ''Tomorrow'' with Tom Snyder.
** ''Later''. First it was a one on one private interview on a simple set between Bob Costas and another person. After Costas left it became ''Later with Greg Kinnear'' with a live audience. A series of rotating guest hosts each brought their own sensibilities to the show. Now it's ''Last Call with Carson Daly'' which is completely different than any of the others.
** ''Series/SaturdayNightLive'''s cast and crew turnover is as legendary as its peak-and-valley history. In fact, the near-constant changing of cast members and writers ''is'' the reason why this show's quality shifts, sometimes for better and sometimes for worse.

!!!Specific Series
* ''HappyDays'': Of all the regular characters that were billed at one point or another during the series' 11-year-run, just four remained from the first through last seasons: Henry Winkler (Fonzie), Tom Bosley (Howard Cunningham), Marion Ross (Marion Cunningham) and Anson Williams (Potsie Weber). Two of the other original characters Ron Howard (Richie Cunningham) and Don Most (Ralph Malph) left after the sixth season, while Erin Moran (Joanie Cunnigham) briefly left for the 1982-1983 season. Of the remaining characters, we all know what became of [[ChuckCunninghamSyndrome Chuck Cunningham]], later addition Scott Baio (as Chachi Arcola) left along with Moran in 1982 but also returned, and various other characters came and went through the years.
* ''Series/SesameStreet'': Much of the cast has rolled over many times, with the exception of Carroll Spinney (Big Bird and Oscar), Bob [=McGrath=] (Bob) and Loretta Long (Susan), who have been there since Day 1 in 1969, although appearances for [=McGrath=] and Long have become less frequent since the mid- to late-2000s. Aside from them, Emilio Delgado (Luis), Sonia Manzano (Maria) and Rosco Orman (Gordon) are by far the longest-tenured actors at 40 or more years, and several Muppet performers have been on the show since almost the very beginning, joining no later than the early 1970s.
* ''TheBill'' lasted for 26 years, starting in 1984. Nearly the entire original cast were still present as of the 1992 season, but there was a gradual erosion from that point onwards. A fair portion of the original cast were still in the show in 2000, but a massive cast clean-out seen the removal of some of these characters (notably Peter Ellis as the Chief Super, who had been a regular since 1984), after which nobody seemed to have contracual immortality anymore. At least one ''original'' cast member (Jeff Stewart as PC Reg Hollis) still managed to stick around until the 24th season in 2008 however, while one cast member from the original 1983 pilot episode (Trudie Goodwin as Sergeant June Ackland) was there until the 23rd season in 2007.
* Since the original ''Series/{{CSI}}'' premiered in 2000, its later seasons have seen the departure of three of its leads (Grissom, retired, and Catherine, new job, and Ray Langston (who replaced Grissom), forcibly resigned), two of its secondary leads (Sara, quit from PTSD but now back as effective regular, and Warrick, KilledOffForReal) and a number of its recurring supporting roles (Wendy, Sofia, and the very short tenure of Riley, meant to replace Sara). Most of the departures were of the "actor wanting to move on" variety, but contract disputes and in Warrick's case, personal problems, also factored.
* In ''Series/{{Degrassi}}'', the cast has changed once since the show started in 2001 (not including Archie "Snake" Simpson):
** Season 5 had the first block of characters graduate from the school, but maintained most of the cast in college. Season 7 had the second half of the initial cast graduate, and they cut down a lot of the older cast leaving four.
** By Season 10 the entire original cast (save Snake) was gone, leaving Chantay as longest time on set (starting in Season 4).
** Clare (introduced in Season 6, made a regular in Season 8) has been on the show longest right now, her class will GraduateFromTheStory in either Season 13 or 14 depending on how they manage the flow of time, marking the second full cast cycle.
* ''Series/DoctorWho'' of course invented TheNthDoctor in order to survive 50 years and counting but also rotates though a long list of the Doctor's companions; the show's time travel premise makes it fairly easy to write old companions out and new ones in.
** The longest-lasting regular cast members have been Creator/TomBaker as the Fourth Doctor (six years, two months), Creator/JonPertwee as the Third Doctor (four years, six months), and Creator/JanetFielding as Tegan Jovanka (three years).
** A special mention for Nicholas Courtney as Brigadier Lethbridge-Stewart. Although he was only a regular cast member for Seasons 7 and 8, he first appeared in Season 5 and made occasional return appearances for years afterwards in ''Doctor Who'', having one last appearance in the SpinOff ''Series/TheSarahJaneAdventures'' before Courtney's death. Meaning he started his role in 1968, and last played the character in 2008 40 years after he was first cast.
** Not only that, senior production staff rotate on a regular basis; the end of 2009 (when Creator/RussellTDavies and Creator/DavidTennant both left) saw the entire creative team and regular cast replaced.
* ''Series/{{ER}}'' transplanted most of its original cast over the fifteen seasons; while some (Susan Lewis) came back and then went away again, and some of the characters came back in the final season, the final cast was composed of none of the members of the original cast. This even gets lampshaded in the final season. One of the new characters meets one of the original characters and they realize that the staff of the hospital changed so much over the years that they have no common acquaintances. All the people who worked in the hospital when the original character left already stopped working there by the time the new character arrived.
* Only James Arness and Milburn Stone lasted through all twenty seasons of ''{{Gunsmoke}}''.
* The cast of ''Series/KidsIncorporated'', which ran from 1984-1993, changed almost every season, and had at least one member drop out with new replacements every season.
* ''Series/LawAndOrder'' ended with a completely different cast than when it started. The first major cast departure happened at the end of season one. The series lost its last original cast member at the end of its tenth season, when Steven Hill's Adam Schiff retired, at which point he'd been the only remaining original for 5 years. So half of its run was done with no one from the first season cast. TheOtherWiki has [[http://en.wikipedia.org/wiki/Law_%26_Order#Casting_and_characters an entire section]] dedicated to the cast/character changes and overlaps.
** Its spin-off ''Series/LawAndOrderSVU'' has now, in its 15th season, almost completely overturned its original cast. Only Mariska Hargitay remains as a constant from season one until now; Ice-T from season two until now. Though unlike its parent program it actually maintained nearly the entirety of its original cast, with the exception of one departure in the second season, for its first twelve seasons.
** ''Series/LawAndOrderUK'' has them all beat with all bar Bradley Walsh having left by the end of the eighth season. When he quit, ITV cancelled the show.
* ''Series/{{MASH}}'' had a significant cast turnover during its eleven seasons. Alan Alda (Hawkeye), Loretta Swit (Margaret), and William Christopher (Father Mulcahy) were the only main cast present for the entire run (although only Alda and Swit were in both the first and last episodes as the role of Mulcahy was RecastAfterThePilot, and Alda was the only one to be in every single episode). Jamie Farr (Klinger) was also present for the entire run of the show, but he started off as an [[AscendedExtra extra]]. The military hospital setting made it easy to write characters in and out with the excuse of them getting drafted, transferred, and discharged.
* ''Series/MysteryScienceTheater3000'' lasted long enough to see every actor walk away for personal reasons. It began as a MadScientist and his [[TheIgor assistant]] tormenting a janitor and his robots, but eventually ended as a megalomaniacal woman, a [[PlanetOfTheApes Doctor Zaius]] {{expy}}, and a [[MysteriousWatcher brain guy]] tormenting an erstwhile temp worker and... well, the same robots, but with different voices. Joel, the creator and main host character, left the show to Mike in the middle of season five, neatly dividing the series (and fans) into two eras. Both hosts went on to start their own movie-mocking franchises in ''WebVideo/CinematicTitanic'' and ''Podcast/RiffTrax''. Both of those shows feature a mutually exclusive subset of MST3K's cast (except for Mary Jo Pehl and Trace Beaulieu, who have appeared in both series).
* Only three regulars of ''Series/NightCourt'' made it all the way through the show's nine-year run: Harry Anderson as Judge Harry Stone, Richard Moll as Bull the bailiff, and John Larroquette as prosecutor Dan Fielding. Three different actresses filled the role of the second bailiff (as different characters). Karen Austin, who played the court clerk and was Judge Stone's original love interest, left before the first season was over and was eventually replaced by Charles Robinson as Mac. Four different actresses played public defenders--Gail Strickland in the pilot, Paula Kelly for the rest of Season 1, Ellen Foley for Season 2, and Markie Post for Seasons 3-9.
* ''Franchise/PowerRangers'' had a few scattered cast changes its first few seasons; most notably ''Series/PowerRangersTurbo'' (Season 5) overhauling the entire roster sans the newly KidAppealCharacter introduced that season at the midpoint. After the show's "Zordon Era" concluded with ''Series/PowerRangersInSpace'' (Season 6), the show adopted a SequelSeries format ala its source material ''Franchise/SuperSentai'' (which always changed casts every season since [[Series/HimitsuSentaiGoranger its inception in 1975]]); there would be occasional crossovers with prior Rangers but otherwise each season starts fresh with a new story and new cast.
* The original UK version of ''Series/{{Shameless}}'' had this in spades. Originally it centred around the Gallagher family and a few neighbours and friends, but as various cast members left, the show shifted focus towards the Maguire family starting around seasons 4-5. The two shared the central role for a few seasons before focus shifted away from a central family and more towards the ensemble cast that had gathered over time. For the final season, only two Gallaghers remain (one of whom wasn't even born until season five) and only three of the original Maguire family. The US version has almost completely averted this so far, in part because of its much more serialised approach to storytelling.
* ''{{Spooks}}'' went through a very large number of cast changes in its run. Only one character, Harry Pearce, appears in all ten seasons and every other position in Section D had at least three different occupants over the show's run.
* ''Series/StargateSG1'', almost. Despite three members of the original Four Man Team making it to the series cancellation (one of them having spent a year [[AscendToAHigherPlaneOfExistence dead]] for [[Literature/TheRestaurantAtTheEndOfTheUniverse tax purposes]]), most of the surrounding cast and all of the big bads were gone two seasons earlier. Only Walter remained unchanged.
* Of the 17 cast members to appear throughout ''Series/{{Smallville}}'s'' run, only Clark and Chloe remained series regulars in all ten seasons. It should be noted that Allison Mack (Chloe) was credited only when she appeared in the final season (less than half the episodes), and was also absent from the credits for the first two episodes of Season 4 to make it seem as though Chloe was dead, so technically Clark was the only character to be a series regular for the entire show.
* ''Series/TwentyFour'' had only Jack Bauer as a main character in all seasons. The first 5 seasons had a pretty consistent cast but after that only Jack Bauer and Chloe (added in season 3) are constants in the remaining seasons.
* After 7 seasons, Spanish series ''Siete Vidas'' had only one character left from the first episode, Sole. She got the last scene in the finale along with two of the most iconic characters introduced in Season 2.
* ''YouCantDoThatOnTelevision,'' whose premise required that most of its cast be kids, would retire its regulars as they got too old, or at least came to look to old. Hostess Christine [=McGlade=] got to stay into her twenties, because she still looked convincingly like a youngish teenager. By its end, the show had a completely new cast except for the two adult regulars (Les Lye and Abby Hagyard).

[[/folder]]

[[folder:Sports]]
* The Boston Celtics from 1957 to 1976. Bill Russell was the only player to win all eleven titles. Havlicek was a member for the latter half of the 60s and the two titles from the 70s. (Nobody from the 1981 Champion Roster was a member back in 1976, making the '80s a {{Reboot}}.)
* The Chicago Bulls under Phil Jackson saw the entire roster (aside from Scottie Pippen) turnover between MichaelJordan's 18 month retirement between 1993 and 1995. Jordan and Pippen were the only leftovers from the first three peat (1990-2) in the second one (1996-8).
* The Houston Rockets had a long-runner cast turnover from 1981 to 1995. (During their four final appearances.) Robert Reid was the only player to play for the Rockets in 1981 and 1986 Finals. Olajuwon was the only player from the 1986 Roster to win the 1993-1994 title with the Rockets.
* The Los Angeles Lakers had a turnover beginning with the 1979-1980 title. A.C. Green was the only player from the '80s to win a Lakers title in the next three-peat.
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[[folder:Web Original]]
* ''Roleplay/TheGunganCouncil'': The only consistent character for 12 years is having a fat Gungan spamming the forums.
* ''Roleplay/TheWake'': There's been so much turnover in the cast over three years that there are only a few characters left who remember pivotal characters and events from early in the game.
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