[[quoteright:317:[[Webcomic/NerfNow http://static.tvtropes.org/pmwiki/pub/images/75e8b67fc57a437f71da4871bdbaa795.jpg]]]]

->''"The fifth book in the increasingly inaccurately-named [[Literature/TheHitchhikersGuideToTheGalaxy Hitchhiker's Trilogy.]]"''
-->-- ''Literature/MostlyHarmless''

The strange tendency of trilogies to expand and see more and more works added to TheVerse. Mainly found in books, but may also occur with movies.

SF author Creator/OrsonScottCard has suggested that this is the result of ExecutiveMeddling; rather than allow an author to write the books he wants to, publishers pressure him into producing sequel after sequel in order to take advantage of the preexisting fanbase and milk a CashCowFranchise bone-dry.

TwoPartTrilogy is somewhat related, typically the result of a one-part story expanding into a trilogy. Contrast DividedForPublication, which is when a work is split into more parts than the author originally envisioned, due to excessive length.

See also FranchiseZombie. CapcomSequelStagnation is a related trope for VideoGames.


[[folder:Audio Plays]]
* In the AudioPlay/BigFinishDoctorWho "Companion Chronicles" series, "[[Recap/BigFinishDoctorWhoCCS5E2EchoesOfGrey Echoes of Grey]]" and "[[Recap/BigFinishDoctorWhoCCS6E3TheMemoryCheats The Memory Cheats]]" were supposed to be the first two parts of a trilogy. The CD notes for the third instalment, "[[Recap/BigFinishDoctorWhoCCS7E2TheUncertaintyPrinciple The Uncertainty Principle]]," make it clear that it is not the planned final part, and the 'trilogy' is now expected to be four episodes long.

[[folder:Comic Books]]
* ''ComicBook/KickAss'' was supposed to be three issues, which then changed to four by the second issue; then it was eight. By the time it ended the comic was now a trilogy consisted of three volumes comprising eight, seven and eight issues respectively, as well as a five-issue Hit-Girl miniseries. And now the franchise is set to be rebooted with a black female protagonist.
* ''ComicBook/{{Runaways}}'' was originally going to be a single miniseries, but the series' success caused Creator/BrianKVaughan to create an ongoing, which was supposed to end with a run by Creator/JossWhedon, but instead led to a third series, a slew of guest appearances and event tie-ins, a new, InNameOnly incarnation, and Nico and Victor getting promoted to off-shoots of ComicBook/TheAvengers.

[[folder:Fan Works]]
* ''WebAnimation/TurnaboutStorm'' is an interesting case. Originally a 4-part series, the episode count increased to five when ''Part 3'' was split into two episodes via SimultaneousArcs, but with the final part still being called ''Part 4'' -- At least until ''Part 5'', the real conclusion, was confirmed via {{Cliffhanger}}.
* In the case of Fanfic/TheCalvinverse, this happened to two different trilogies at the same time - Creator/{{Swing123}} and Creator/{{garfieldodie}} both made their own separate ''ComicStrip/CalvinAndHobbes'' trilogies, and ultimately ''Fanfic/RetroChill'' served as a {{crossover}} between the two (cementing the series as a universe, it could be said).

[[folder:Films -- Animated]]
* ''WesternAnimation/ToyStory3'' seemed like a fitting conclusion to a beloved franchise, providing the closure that every fan wanted. Everyone expected it to be the grand finale to the series. But then it became the first animated film to make a billion dollars at the box office, and its follow-up shorts and TV specials ended up pulling in huge numbers. Hello ''WesternAnimation/ToyStory4''!
* For a long while, ''Franchise/WallaceAndGromit'' consisted strictly of three short films: ''WesternAnimation/AGrandDayOut'', ''WesternAnimation/TheWrongTrousers'', and ''WesternAnimation/ACloseShave''. Many years later, there would be a full-length fourth entry, ''WesternAnimation/TheCurseOfTheWereRabbit'', as well as a fifth short film, ''WesternAnimation/AMatterOfLoafAndDeath''.

[[folder:Films -- Live-Action]]
* The ''Film/AmericanPie'' trilogy, direct-to-video spinoffs aside, later got a fourth movie: ''American Reunion''. A fifth movie has been stated to be likely.
* One of the taglines for ''Film/ScaryMovie4'' was "The Fourth and Final Chapter of the Trilogy"... Then ''Film/ScaryMovie5'' came out. In France, ''Film/ScaryMovie3'' had the tagline [[CaptainObvious "Best trilogies are in three parts."]][[note]]which is probably a [[BlindIdiotTranslation mangling]] of the American tagline, "Great trilogies come in threes."[[/note]] For that matter, it wasn't even the first time they had pulled such a stunt. One of the [[{{Tagline}} taglines]] for the original ''Film/ScaryMovie'' was "No shame. No mercy. No sequel." One of the taglines for the second film was "[[ILied We lied.]]"
* ''Film/{{Alien 3}}'' is the definitive ending for the story of Ellen Ripley, who [[spoiler: died by simultaneously falling into molten lead and giving birth to a Xenomorph queen]]. However, ''Film/AlienResurrection'' brought the character back as a clone who finally made it to Earth. Up until the release of the ''Alien Legacy'' box set in 2000, the first three movies were still packaged in one case as the "Alien Trilogy", with the fourth film packed in separately. It's also been released as a "Quadrilogy"[[note]]the correct word for a sequence of four is "tetralogy"[[/note]] and an "Anthology" (to say nothing of the spinoff ''Franchise/AlienVsPredator'' films or the 2012 pseudo-prequel ''Film/{{Prometheus}}'').
* The ''Franchise/IndianaJones'' trilogy was expanded with [[Film/IndianaJonesAndTheKingdomOfTheCrystalSkull a fourth movie]] after a nineteen-year hiatus. Justified in that the Indiana Jones series was originally intended to be five or six movies long anyway, but things just kept getting in the way of development. In the meantime, much material was added to the ExpandedUniverse.
* ''Film/LiveFreeOrDieHard'' and ''Film/AGoodDayToDieHard''. Something of a stretch, since the ''Film/DieHard'' series doesn't really have an overarching storyline anyway.
* ''Film/SpyKids''. However, it's not really a continuation of the first three, since it's centered around a new family (the family of the previously-unmentioned aunt of the original spy kids, to be exact), though the original spy kids, now grown-up, do appear.
* Film/TheViewAskewniverse, which started out as the Jersey Trilogy and became the Askewniverse Chronicles. There are six films released, with ''Clerks 3'' on the way.
* ''Franchise/PiratesOfTheCaribbean''. However, [[Film/PiratesOfTheCaribbeanOnStrangerTides the fourth film]] is an entirely new adventure featuring [[BreakoutCharacter Jack Sparrow]], rather than a continuation of the previous films' arc. A fifth film was later made.
* ''Film/ParanormalActivity'' came out with a [[Film/ParanormalActivity4 fourth film]] in an obvious attempt to [[CashCowFranchise get more money from the fans]]. Not surprisingly, both critics and fans agree that this is the worst one in the series.
* ''Franchise/StarWars'': The Original Trilogy (Episodes IV-VI, formerly referred to as the "Star Wars Trilogy") was later expanded with a new "Prequel Trilogy" of movies (Episodes I-III), as well as [[Franchise/StarWarsExpandedUniverse multiple television series, games, books and comics]] in spin-off material. Though many had believed the saga was completed with ''Film/RevengeOfTheSith'' in 2005, a new "''Sequel'' Trilogy" (Episodes VII-IX) is currently in production following Creator/{{Disney}}'s acquisition of Lucasfilm in 2012, as well as new spin-offs. Justified in that ''Star Wars'' was not originally intended to be just a trilogy, with initial plans aiming for a twelve-movie saga including prequels and sequels. Then George Lucas shortened to nine following the first movie, and settled on six after the second.[[note]]Although how much of any of this was ''actually'' Lucas's original vision seems to depend on [[FlipFlopOfGod when he actually said it]].[[/note]] The first movie of the third trilogy, ''Film/TheForceAwakens'', was released in December 2015.
* ''Film/SawI'' was originally intended to be a stand-alone film. Because of the astounding success of that one, they decided to end on the [[Film/SawIII third movie]]. Obviously, they came back after the third one and just decided to flesh out a story and keep writing until they came up with the perfect ending. They came up with an additional 5 scripts. The trope was slightly subverted when they had to cut down to 4 scripts because of the success of the ''Film/ParanormalActivity'' franchise, which would later cause the death of the ''Franchise/{{Saw}}'' franchise.
* Almost occurred with the ''Film/SpiderManTrilogy'', with a fourth film in development after ''Film/SpiderMan3'' had wrapped up the current plot threads, but due to CreativeDifferences the franchise was [[ContinuityReboot rebooted]] with ''Film/TheAmazingSpiderMan'' instead.
* Creator/GeorgeARomero's ''Film/LivingDeadSeries''. The original ''Film/NightOfTheLivingDead1968'', ''Film/DawnOfTheDead1978'' and ''Film/DayOfTheDead1985'' stood as a trilogy for 20 years and became a hallmark of the zombie film genre before receiving a fourth installment in ''Film/LandOfTheDead'', which got some great reviews but was viewed by some fans as a disappointment. Two more installments, ''Film/DiaryOfTheDead'' and ''Film/SurvivalOfTheDead'', came out in rapid succession, to very little cultural impact.
* ''Film/{{Scream 4}}'', though given that this is the ''Franchise/{{Scream}}'' series, [[LeaningOnTheFourthWall it took a couple digs at this.]]
* The credits for ''Film/ViolentShit III: Infantry of Doom'' read "End of Trilogy". Cue another sequel, ''Karl the Butcher vs. Axe'', eleven years later.
* ''Deadly Dares: Truth or Dare Part IV'', made thirteen years after ''Screaming for Sanity: Truth or Dare 3''.
* ''Film/{{Rambo|IV}}'' (2008), which is more informally known as ''[[FanNickname Rambo 4]]'', arrived in theaters a full two decades after the final installment in the original ''First Blood'' trilogy that introduced the character to movie audiences. The fourth film isn't really that gratuitous, however, since it allows John Rambo some closure by having him, at the film's very end, [[spoiler: [[CrowningMomentOfHeartwarming finally return to his father's ranch in Arizona]], which he has been away from for close to 40 years]].
* Film/TheBourneSeries was seemingly a full-circle trilogy... until a SpinOff fourth installment, ''Film/TheBourneLegacy'' came out in 2012. Then a fifth film came out in 2016 [[ProductionPosse by the same team as the first three films]] (minus scriptwriter Tony Gilroy).
* ''Film/MadMax'' was a trilogy for 30 years - and then came ''Film/MadMaxFuryRoad'', which even required a change of [[TheOtherDarrin lead actor]] and [[CaliforniaDoubling filming location]]. George Miller has stated it will start a whole trilogy.
* The Franchise/MarvelCinematicUniverse is an interesting case in that the currently untitled fourth Avengers film will be the first time a sub-franchise will be more than a trilogy. That said, the story arcs of individual characters such as Iron Man, Thor, and Captain America have evolved over the course of their solo film trilogies in addition to the other films they appear in, blurring the distinction of what constitutes an individual film series and the franchise as a whole. Further, the untitled Avengers film is supposed to act as a culmination of the previous ten years of film, but it will most surely continue after that.

* L. Frank Baum tried to end the ''[[Literature/LandOfOz Oz]]'' series at the sixth book, stating that there would be no way to ever contact the Land of Oz anymore. That didn't happen, of course, and he wrote eight more books before dying, at which point the publishers handed the series off to Ruth Plumly Thompson.
* Creator/OrsonScottCard, who discussed this trope above, is no stranger to this.
** ''Literature/TheTalesOfAlvinMaker'': The fourth book of going-on-seven opens with a chapter-length rant from the author that's titled "I Thought I Was Done" and justifies its existence by meandering into and out of setting background.
** ''Literature/EndersGame'' began as a novelette. When he tried to expand it into the novel ''Literature/SpeakerForTheDead'', he realized it would have a very slow, boring beginning--but if he stretched that beginning out even further, and turned it into a novel of its own, he'd be able to add details and character development and make it more interesting. Then his publisher accidentally wrote out a contract for "the Ender trilogy," and he had to [[DolledUpInstallment rewrite a planned standalone]] called ''Philotes'' into the third book. Then he realized just how long ''Philotes'' was, and split it into two books, ''Literature/{{Xenocide}}'' and ''Literature/ChildrenOfTheMind''. [[spoiler:Killing off the main character]] nearly ended the series, but then he realized the thousand-year TimeSkip between books 1 and 2 allowed for plenty of {{Interquel}}s. Now the series is up to double digits, including one that takes place during the TimeSkip at the end of the first book.
* ''Literature/TheHitchhikersGuideToTheGalaxy''
** Creator/DouglasAdams' "trilogy" eventually ended with the fifth book, ''Literature/MostlyHarmless''. He [[LampshadeHanging Lampshaded]] it by calling it a "trilogy in four parts" after the fourth book came out and an "increasingly inaccurately-named trilogy" after the fifth. The first three books go together quite well, and the last two seem a bit awkwardly tacked on. The fifth book seemed to be a case of TorchTheFranchiseAndRun, but he later revealed that [[CreatorBreakdown the ending was more due to his mood]] than anything and he regretted it. He would have un-torched the 'verse in a sixth book, [[AuthorExistenceFailure but alas, unfortunately]]...
** Eoin Colfer (writer of the Literature/ArtemisFowl books) has written ''Literature/AndAnotherThing'', making this a trilogy of six. The book emphasizes the idea of "no endings" throughout, and while it could be a conclusion to the series, it points furtively in the direction of an ongoing story. The book's cover states that it is "Part Six of Three".
** ''Literature/TheSalmonOfDoubt'', which contains excerpts from an additional ''Dirk Gently'' novel that Adams was developing at the time of his death, includes notes that he was beginning to feel ''Mostly Harmless'' was not the appropriate place to end the ''Hitchhiker's'' series (it was a bad CreatorBreakdown, ending with [[spoiler:all AlternateUniverse Earths destroyed and and 80% of the main cast dead.]]), and implies that ''Salmon'' would either have been retooled into the sixth part, or a {{crossover}}.
* Creator/IsaacAsimov's ''Literature/{{Foundation}}''. Several of his more well-known stories are actually one [[TheVerse universe]], through CanonWelding. He was a tremendously prolific writer, so only a small fraction of his actual work fits into the background and timeline of the Robots/Foundation [[TheVerse 'verse]], but that fraction includes some of his most popular stories. It should be noted, though, that the familiar trilogy was originally published in ''eleven'' installments[[note]]Book 1 is the first four stories, plus a framing story; Book 2 is two stories, one of which was published as a two-part serial, and book 3 is also two stories, one of which was published as a three-part serial[[/note]].
* When Bernard Cornwell was inspired by the popularity of the ''Literature/{{Sharpe}}'' television series to write some more novels, he wrote three books set prior to the Peninsular War setting of the existing novels. They were quickly dubbed the prequel trilogy by fans. Then he wrote two more. (Although as the first three concerned Sharpe's adventures in India and the other two dealt with the earlier part of the Napoleonic conflict, they seemed to have been rebranded the India trilogy.) In the end, he only moved on to other projects when he ran out of early 19th century wars for [[TheGump Richard Sharpe]] to fight in. [[TropesAreNotBad The quality of writing remained consistently good throughout.]]
* Creator/AnneRice's ''Literature/TheVampireChronicles''.
* Creator/MargaretWeis seems particularly prone to this:
** The ''TabletopGame/{{Dragonlance}} Chronicles'' trilogy received a fourth book, ''Dragons of Summer Flame'', which wasn't written until after several other series and standalone works had been made in the same verse. It was written 14 years after the third book, took place 30 years after, and didn't star any of the characters from the originals (though some of them did have supporting roles). Many feel that the only reason it was dubbed part of the ''Chronicles'' series was for [[DolledUpInstallment marketing purposes]].
** The ''[[Literature/TheDarkswordTrilogy Darksword]]'' "trilogy" by Weis and Hickman consists of four books. The fourth is written in a somewhat different style than the rest (taking place after a TimeSkip and being narrated by a new character), but does conclude important plot threads that the third book left dangling. There is also another book (Darksword Adventures) which is half novella set in the same setting as the trilogy, and half {{RPG}} system.
** Weis's solo series ''Literature/TheStarOfTheGuardians'', whose third book concluded with the main character rightfully crowned king and all the main characters getting what they deserved... Including the NominalHero, who faked his death and returned to a life of penitent obscurity in light of his now-dead OneTruePairing. Then Weis published a fourth book to clean ''them'' up. (And, even better, she then took her version of the MagnificentSeven to AscendedExtra levels by publishing a trilogy about ''them''! They're not really related, and main characters from ''Guardians'' rarely appear in ''Mag Force 7'', but, still.)
* ''Franchise/{{Dune}}'' is an interesting example. ''Literature/{{Dune}}'' was actually conceived as one long book, with the sequels ''Literature/DuneMessiah'' and ''Literature/ChildrenOfDune'' fitting directly after the first. ''Messiah'' was fleshed out while writing ''Dune'' and eventually became its own novel, which due to its expansion then warranted ''Children'' to be expanded as well and also became its own book. ''Literature/GodEmperorOfDune'' and the last two in the series, ''Literature/HereticsOfDune'' and ''Literature/ChapterhouseDune'' are genuine examples of a trilogy creep, though the fact that the story is now over ''10,000'' years past in the originals, it's fair to say that they're a trilogy of their own. [[AuthorExistenceFailure Before he died]], Herbert planned to write a seventh book which would've been the last of a trilogy, with ''God Emperor'' serving as a bridge between the first and second trilogies. With this all said, someone "found" notes in a safe/vault/deposit box supposedly with a lot of notes on how the series was supposed to end. What happened? A [[Literature/PreludeToDune prequel trilogy leading up to the original Dune]] novel. Followed by a [[Literature/LegendsOfDune pre-prequel to the whole series set in the distant past]]. And finally the [[Literature/HuntersSandwormsOfDune closure of the series]]... followed by [[Literature/HeroesOfDune more books in the form of interquels]](?). The canonicity is up for debate among fans.
* ''Literature/TheWheelOfTime'' was supposed to be a trilogy. Eleven books later, [[AuthorExistenceFailure the author died]]. And what was meant to be the twelfth and final book has since expanded to form its own trilogy. At World Con 2008 Tom Doherty of Tor Books finally put this long-standing rumour to rest: it was originally planned to be six books when Robert Jordan proposed the series to him in 1984, before he even started writing the first book. It's also been stated that Jordan planned for it to be three but Doherty made it a six-book deal due to Doherty's knowledge that Jordan always wrote more than he thought he needed in the first place. Jordan's original plan was for Rand to get Callandor at the end of the first book.
* ''Literature/InheritanceCycle'' also got a fourth book. The page was originally called ''The Inheritance Trilogy'' until the announcement. In this case, it's because the fourth book didn't expand the story, the third and fourth book just got too long to release as one. At 866 pages the last book is almost as long as the entire The Lord of the Rings story. The third book, Brisingr, is another 750 pages so splitting it up was a logical choice.
* For many years there were three novels in Creator/UrsulaKLeGuin's Literature/{{Earthsea}} setting, and they were called the Earthsea Trilogy. Then came ''Tehanu: The Last Book of Earthsea'', and the series was renamed to the Earthsea Cycle. "The Last Book of Earthsea" has been followed by another novel. And that's without mentioning the short stories.
* The ''Literature/{{Belgariad}}'' was planned to be a trilogy ("Belgarion", "Ce'Nedra" & "Torak"). Eddings explains in ''The Rivan Codex'' that due to length and the publishing standards of large book chains at the time, his publisher convinced him to do a pentalogy instead. Then, when he was writing book four, he realised that he was going to have plenty of material left over, and the second pentalogy was planned. And when that wasn't enough, they went and planned a prequel, that in fact saw the light as two... Of two books each. ''Literature/TheElenium'', on the other hand, ''was'' a trilogy that received ''another'' trilogy of sequels.
* Creator/PiersAnthony lampshades this by marveling at how long the ''Literature/{{Xanth}}'' "trilogy" has become in the afterword to one of the books. He then mentions the possibility of working on more books in the ''Apprentice Adept'' series, since that trilogy was "looking a little sparse" at only three books. It eventually reached seven. The first Xanth "trilogy" happens to have 27 books, with the last of these being titled "Cube Route" (and since 3 cubed is 27, this is another of Piers' in/famous puns). In fact, this seems to happen to Anthony a lot. The Cluster trilogy ended up being supplemented with two {{Interquel}}s. The ''Literature/IncarnationsOfImmortality'' series, though never a trilogy, ended up three books longer than originally planned. As for the Literature/ApprenticeAdept Trilogy - it's now two trilogies and a seventh standalone.
* Mickey Zucker Reichert's ''[[Literature/TheLastOfTheRenshai Renshai]]'' trilogy started out as a stand-alone trilogy. Then she wrote a sequel trilogy. And then she wrote a sequel to the sequel trilogy.
* Mostly averted by Creator/TadWilliams; his novels are about as {{Doorstopper}} as they come, but his series last exactly the number of books that he intends them to last. However, ''To Green Angel Tower'' (of the ''Literature/MemorySorrowAndThorn'' trilogy) was split into two books for the paperback edition and at least one translation. This inadvertently happened with another trilogy of his, in that the book became so huge that it had to be split in half. It's not so much "trilogy creep" as "trilogy overflow."
* Creator/RobertRankin's ''Brentford Trilogy'' has seven books. The ''Armageddon'' series, perhaps in reference to this, is called an Octology, despite there only being three books in it.
* Creator/StephenKing declared in his afterword to ''Literature/TheGunslinger'' that he foresaw ''Franchise/TheDarkTower'' eventually comprising six to seven novels, spanning 3,000 or so pages, and taking anywhere from 20 to 300 years to write. He made good on the ''letter'' of his promise; the finished series is seven books and runs a little over 3,000 pages, but the series itself [[CanonWelding spilled over]] into over a dozen of his other novels, which amounts to tens of thousands of pages overall.
* In the foreword for ''Literature/BlandingsCastle'', Creator/PGWodehouse jokes about this by referring to the 'saga affliction' that grabs the attentions of unwary authors and forces them to think up more and more ideas for what was intended to be just one story.
* John Marsden's ''[[Literature/TheTomorrowSeries Tomorrow, When the War Began]]'' series was originally a very tightly written trilogy, that afterwards ended up seven books. There is also a post-war series as well now.
* Creator/RaymondEFeist's ''[[Literature/TheRiftwarCycle Riftwar Saga]]'' was written as a trilogy (''Magician'', ''Silverthorn'', ''A Darkness at Sethanon''). The first book was [[ExecutiveMeddling edited for size]] by the US publisher. Later, for the paperback edition the original content was restored, but the resulting text was split into two books (''Magician: Apprentice'' and ''Magician: Master''). The UK publisher still produces ''Magician'' as a single volume.
* Creator/JohnChristopher's ''Literature/TheTripods'' had a prequel added to it about 20 years after the original. This was not a bad story ''by itself'', but some felt it was a poor fit to the classic series.
* ''Literature/ASongOfIceAndFire'' was originally slated to be three books. By the end of book two, the writer realized he couldn't do it in three, and so expanded it to four. Since then, he's expanded that to six, and then splitting the fourth book in two, making it seven. If he can keep it that way, it would be fortuitous, as within the world of the books seven is an important number.
** The French translations of large fantasy cycles almost never use the words "trilogie", or "tetralogie", or whatever, even when they were used for the original. This is because the publishers smelled the cash-cow and made it an habit to split each book into two, three, or even four parts. The French version of ''A Song of Ice and Fire'' is currently a ''dodecalogy'' and this bizarro-version of the TrilogyCreep will eventually require the French speaking fans to shell upward of 200 euros just to get the completed series in paperback.
** In the UK, books three and five of ''A Song of Ice and Fire'' were each published in two parts, so as of 2012, there are already seven books in the series.
* Creator/JohnScalzi's ''Literature/OldMansWar" trilogy has now gained a fourth book, retelling the events of the third book from another character's POV.
* Stephenie Meyer's publishers wanted her to stop at three books about [[Literature/{{Twilight}} Bella and Edward]]. She took four books to finish out their story, and planned on writing the first book from [[PerspectiveFlip Edward's point of view]], but that was scrapped when [[CreatorBreakdown the rough draft was leaked online]].
* Lynn Flewelling's ''Literature/{{Nightrunner}}'' series gained a fourth book years after the first three were originally published, but this wasn't a change of plan: book three had an author's note explicitly stating that "This is not a fantasy trilogy; it's a series that happens at the moment to be three books long".
* David Gerrold originally planned for his ''Literature/TheWarAgainstTheChtorr'' series to be a trilogy, before he realized he was going to need more room. It's currently up to four books.
* Creator/RobertLudlum's ''Literature/TheBourneSeries'' has a clear ending in book three, as [[spoiler:Bourne/Webb finally kills his nemesis Carlos the Jackal]]. After Ludlum's death Eric van Lustbader continued the series. Interestingly [[Film/TheBourneSeries the film adaptations of the books]], which bear only the most superficial resemblance to their source material, also provide a definite ending in the third entry. But then they started making ''Bourne 4''.
* Anne Bishop's [[Literature/BlackJewels The Black Jewels Trilogy]] has six books (and a short story/novella) collection. Averted in that the first three books are a coherent trilogy (all with titles Noun of the Noun), followed by a prequel, followed by the collection which has prequel, inter, and epilogue stories, followed by two epilogue novels.
* The ''Literature/MaximumRide'' series was originally planned to end after ''Saving the World and Other Extreme Sports''. Many fans think that this should've happened, as it resolved everything except the Fang/Max subplot ([[spoiler:In that version of the plot, Jeb really was the voice]]), and there was a significant drop in quality after that book. ''Angel'' was supposed to be the next finale to the series, then the next book ''Nevermore'' was, and then ''Maximum Ride Forever'' was released.
* Diana Gabaldon's ''Literature/{{Outlander}}'' was originally supposed to be two books, then three, then four, then a double-trilogy. The seventh book came out in Fall 2009. The author never explicitly said to her publishers that it was ''supposed'' to be a trilogy-- only that she had at least two more books after the first in her, and she ran with that. Several of the Lord John stories exhibit short story creep, since Gabaldon's idea of a [[{{Doorstopper}} short]] story grew into a publisher's idea of a complete novel.
* Creator/HarryTurtledove, particularly since it was unexpected: his [[Literature/{{Timeline191}} TL-191]] series started with a one-off prequel, ''How Few Remain'', then a trilogy called ''The Great War''. All of which fitted the planned releases that had been "Coming Soon" in the fronts of his novels for years. Then suddenly the one round-up book that would have dealt with events later on, called ''The Great War: Settling Accounts'', grew to '''seven huge books''', the ''American Empire'' trilogy and then the ''Settling Accounts'' tetralogy. The vast amount of padding and repetition involved in these seven, along with what is broadly considered to be a significant decline in writing quality, has led [[Website/AlternateHistoryDotCom some]] to accuse Turtledove of deliberately writing {{Doorstopper}}s to put his kids through college.
* Jane Yolen's ''Pit Dragon Trilogy'' became the ''Literature/PitDragonChronicles'' when a fourth book was released... [[SequelGap over two decades after the trilogy "ended."]]
* ''Literature/TheEmigrants'' by Vilhelm Moberg was originally intended as a trilogy, but the third book was split into two. It is even more noticable in the original Swedish titles, where the fourth book has an OddNameOut (''The Emigrants'' about leaving Sweden, ''The Immigrants'' about arriving in America and traveling to where land is handed out, ''The Settlers'' about starting up farming in a new country - and ''The Last Letter Home'' continues that story). The second book is normally called ''Unto a Good Land'' in English.
* Scott Westerfeld dedicated "[[Literature/{{Uglies}} Extras]]" to "everyone who wrote to me to reveal the secret definition of the word 'trilogy'". Proving TropesAreNotBad, "Extras" is essentially a companion piece with some trilogy characters as {{Special Guest}}s.
* Chris Walley's ''Literature/LambAmongTheStars'' trilogy is actually an {{aversion}} in that when the third book was written and found to be a {{Doorstopper}}, Walley went back and edited the first two books into a single book. The new third book ends the series in such a way that it would be incredibly difficult to continue it. This was a case of subverted ExecutiveMeddling, since Tyndale asked him to do it. Subverted in that having three similar-sized books works much better than two small and then two large.
* Creator/CassandraClare's ''Literature/TheMortalInstruments'' provide a rather outrageous example. First, there was the original trilogy (''City of Bones'', ''City of Ashes'', and ''City of Glass''). Then, it was announced that Clare was writing ''Literature/TheInfernalDevices'', a steampunk prequel trilogy set in Victorian London (''The Clockwork Angel'', ''The Clockwork Prince'', and ''The Clockwork Princess''). ''Then'', a fourth book centered around the Simon character of the first trilogy was revealed to be in the works (''City of Fallen Angels''). '''''Then''''' Clare decided to add two more books to ''The Mortal Instruments'' story (''City of Lost Souls'' and ''City of Heavenly Fire'') while also stating that this new trilogy of MI books would no longer focus solely on Simon but rather on the entire cast. This YA fantasy book series literally tripled in size. Almost humorously, after writing ''City of Glass'' Clare stated in an interview that she liked half-open endings, and deliberately left hers that way, and that she had no intention of continuing it.\\
It has far more than tripled now. In addition to ''The Mortal Instruments'' and the ''The Infernal Devices'', there are three new trilogies in the works; ''Literature/TheDarkArtifices', ''The Last Hours'' and ''The Wicked Powers''. Note that all of these are separate series within the same universe, and each trilogy (not including the double-trilogy of ''The Mortal Instruments'') is written so that it can be read on its own.
* ''Literature/TheIcemarkChronicles'' was originally supposed to be a trilogy, but the author has announced he intends on writing a fourth, set before the trilogy.
* The first three books of [[Literature/{{Dragons}} The Last Dragon Chronicles]] form a definite trilogy, with a complete story, and a ''very'' definite ending. The rest do continue it, but begin a new story arc altogether.
* The Literature/SecretHistories series was originally planned to be a trilogy, but the series proved so popular that Creator/SimonRGreen decided to make it into an ongoing series.
* From Creator/JohnRingo:
** His ''Literature/TroyRising'' series was originally planned to be a trilogy, but word on the Ringo forum on [[Creator/BaenBooks Baen's Bar]] is that his Muse is insisting on continuing the series, much to the joy of many of his readers. The current plan is for five books total, unless Ringo's Muse insists on more.
** As mentioned in the foreword for ''Strands of Sorrow'', there was originally only supposed to be three main books in the ''Literature/BlackTideRising'' series, with at least one collection of short stories written by various writers set in the Black Tide Rising universe, but Ringo's Muse wouldn't let go, and at the insistence of a wife that was getting tired of his pacing around ''Strands'' was written.
* Meg Cabot's ''Literature/ThePrincessDiaries'' series was planned to be a trilogy, and the first three books do make for a complete story, but Cabot kept writing books until they reached the number of ten, not counting spin-offs.
* The "The New Prophecy" arc in ''Literature/WarriorCats'' was conceived of as a spin-off trilogy, but turned into a six-book sequel series.
* ''Mattimeo'', the third book in the ''{{Literature/Redwall}}'' series, ended on a note that was clearly supposed to be a wrap-up. Trouble is, author Brian Jacques got addicted to the universe he'd been writing in and had written 22 books (plus additional material) by the time he died.
* ''[[Literature/TheChroniclesOfNarnia The Lion, The Witch, and the Wardrobe]]'' was originally intended to be a single, self-contained story. Then Lewis decided to write a sequel. Then he wrote a third book, and made sure to make it very "final": the characters sail over the edge of the world and find themselves in Aslan's (IE God's) country, the two protagonists remaining from the first book are told that they will not be returning to Narnia, and Aslan reveals to them his full glory. He ended up writing more books, but stopped at seven, deciding it was a good number to end on.
* Just before ''Silence'' -- the third book of the ''Literature/HushHush'' trilogy came out, the author announced that she would be writing a fourth book (''Finale'')too.
* Creator/SergeyLukyanenko originally just wrote ''Literature/NightWatch'' as a single novel. Following its success (in Russian-speaking countries), he continud with ''Day Watch'' and ''Twilight Watch'' with the co-author of ''Day Watch'' writing a spin-off featuring none of the main characters. Then followed ''Final Watch''... and ''New Watch''. Many fans agree that the series has long ago [[JumpingTheShark jumped the shark]]. In 2014 Lukyanenko published ''Sixth Watch'', stating it to be [[ExactWords "the last novel about the magician Anton"]], and where [[RefugeInAudacity shark jumping]] [[WorldOfHam became a spectator sport]]. Earlier the same year he turned the series into a SharedUniverse, inviting younger authors and promising strict quality control over what gets published. As of 2015 fans' reaction to new collaborations is yet mixed and undecided.
* Creator/SpikeMilligan's war memoirs started with ''Literature/AdolfHitlerMyPartInHisDownfall'' and were planned as a trilogy. Eventually, there were seven books, extending out significantly beyond the actual war.
* Averted with ''Literature/TheLightbringerSeries''. The author intended for it to be a trilogy, but purposefully named it "Series" just in case he went over. And indeed, he later started with a fourth... and a fifth.
* Brian Lumley's ''Literature/{{Necroscope}}'' series was supposed to be a trilogy, and book three does have a fairly solid BittersweetEnding, but then he figured it was too much of a downer and wrote two more books which ended the series on another bittersweet ending. This was expanded by another three books (''Necroscope: Vampire World'') providing ''another'' bittersweet ending to the series. Which was then continued in a pair of {{Interquel}} works which ended on a flat out DownerEnding just to shake things up. Finally another three books followed in which, not only was another bittersweet ending, but also with Lumley deciding to TorchTheFranchiseAndRun. Which closed out the former trilogy on book ''thirteen''. Except for the novella, short stories, and another {{Interquel}} book he later wrote.
* S. Andrew Swann's Literature/MoreauSeries had a fourth book, ''Fearful Symmetries'', added on five years after the original trilogy was completed.
* Lois Lowry's ''Literature/TheGiver'' (1993) had two sequels, ''Literature/GatheringBlue'' (2000) and ''Literature/{{Messenger}}'' (2004), and was fittingly referred to as "the ''Giver'' trilogy" for eight years. Eight years later, ''Literature/{{Son}}'' is released, definitively tying up loose ends and making it a quartet.
* ''Literature/TheBartimaeusTrilogy'': It was a trilogy, then along came the announcement of a prequel. The page is still called "The Bartimaeus Trilogy", even after the release of the prequel. This is reasonably fair, though, as the prequel book is very much a self-contained story and only features two characters seen in the original novels: Bartimaeus himself and his long-time antagonist, Faquarl.
* An odd case in the case of the Literature/GreenSkyTrilogy. The first book set up the story, the second was more or less a PerspectiveFlip from Teera's POV, the third dealt with the fallout of the events on the first two books. But... Snyder decided to play DeathByNewberyMedal on a lead character and realized she shot herself in the foot. Then, a software designer shows up, wanting to make an adaptation of her books. Cue what was perhaps the first video game to be called a {{canon}} sequel.
* Inverted with ''Literature/TheLordOfTheRings'': when Tolkien finished it, it was in six 'books', with Tolkien wanting it published either all at once or possibly in two volumes. His publishers split it into a trilogy.
* Early editions of ''[[Literature/PercyJacksonAndTheOlympians The Lightning Thief]]'' and ''The Sea of Monsters'' had "Percy Jackson & the Olympians '''Trilogy'''" written on their spines. There ended up being 5 books in the series.
* Philip Pullman's ''[[Literature/HisDarkMaterials His Dark Materials]]'' series was originally a trilogy. It was followed a few years later with two novellas, Lyra's Oxford and Once Upon a Time in the North, and another full novel, The Book of Dust, was expected... and ended up morphing into a trilogy of its own.
* For the first two books, the ''Literature/TheLostYearsOfMerlin'' series by T.A. Barron was advertised as a trilogy. With the third book, it was decided that two more would follow and the billing for the series became an "epic" instead. In the introduction for the third book, the author states that Merlin himself told him that three books would not be enough. This isn't quite so galling, though, when you consider that in the introduction to the first book, he states that the story came to him through Merlin.
* When the first novel of ''Literature/WindAndSparks'' cycle was published, Alexey Pehov said that the story got too long for a single book, but he'll wrap it up in the second one. Then in the third. It ended up as four novels and two prequel short stories. The irony? It was inspired by ''Literature/TheWheelOfTime'' (but less epic, a bit darker, much snarkier), with a helping of ''VideoGame/{{Thief}}'' and ''Literature/GarrettPI''.
* A 1979 boxed set refers to ''Literature/AWrinkleInTime'' and its sequels ''A Wind in the Door'' and ''A Swiftly Tilting Planet'' as the Time Trilogy. Officially it's the Time Quartet (as of ''Many Waters)'' or the Time Quintet (including ''An Acceptable Time)''.

[[folder:Live-Action TV]]
* ''Series/KamenRiderDenO'''s third movie was explicitly called "Farewell Kamen Rider Den-O: The Final Countdown", and features a PassingTheTorch aspect with the introduction of a new Den-O, and on a meta level it was believed to be the end of the series because star Takeru Satoh was moving on to other roles. Another three / five ''Den-O'' movies[[note]]depending on whether you count the Chō Den-O Trilogy movies as one big one or three smaller ones[[/note]] have come out since then. Possibly lampshaded in the DVD release of "Final Countdown", where a short extra cartoon has one character remark that, for all the talk of "final" and "conclusion", that doesn't stop them from making more sequels.
* For some reason, CBS advertised the ''Series/PersonOfInterest'' episodes "The Cold War," "If-Then-Else," and "Control-Alt-Delete" as a trilogy, but the next episode "MIA" is a key part of the arc.

* The Music/{{Rush}} song "Where's My Thing?" is described as part IV of the Gangster of Boats trilogy. [[{{Uninstallment}} There kinda actually wasn't any Gangster of Boats songs before it.]]
** Played straight with ''Vapor Trails''' "Freeze (Part IV of Fear)." Fear is a "trilogy" that was [[AnachronicOrder released in reverse order]] with Part III, "Witch Hunt," from ''Moving Pictures'' first and Part I, "The Enemy Within" from ''Grace Under Pressure'' released third.
* Played straight AND subverted by Music/BadReligion, where Part III received a sequel and a prequel on the album 'Suffer' in Part II (The Numbers Game) and Part IV (The Index Fossil), but no Part I. [[WordOfGod Brett Gurewitz, when asked by a fansite, cited Big Bang as the closest to Part I that he could think of.]]

* Though ''Theatre/DerRingDesNibelungen'' was not originally conceived as a trilogy, it was already four plays by the time Music/RichardWagner began composing the music, and is not commonly thought of as a trilogy, its official heading is "a stage festival play for three days and one evening before."
* It is believed by some scholars that Creator/WilliamShakespeare wrote the three ''Theatre/HenryVI'' plays out of sequence: first [[Theatre/HenryVIPart2 Part II]], then [[Theatre/HenryVIPart3 Part III]], then finally [[Theatre/HenryVIPart1 Part I]]. Moreover, from a critical and performing standpoint, they are often lumped together with ''Theatre/RichardIII'' as an overall "UsefulNotes/WarsOfTheRoses" story.

[[folder:Video Games]]
* ''Franchise/KingdomHearts'' had two games come out between parts ''I'' and ''II''. There have been four more titles released since ''II'' in 2006, with ''Kingdom Hearts III'', ostensibly the GrandFinale of the current series, slated for a release some time in 2018. Not counting {{Updated Rerelease}}s and compilation titles, that's nine games in this "trilogy."
* ''Franchise/{{Halo}}'' is an interesting case, as Creator/{{Bungie}} originally planned for it to only be '''two''' games; [[ExecutiveMeddling Microsoft wanted a third game]] and development time for ''Halo 2'' ran short, so they stretched it out over ''VideoGame/{{Halo 2}}'' and ''VideoGame/{{Halo 3}}''. Then there's ''VideoGame/Halo3ODST'' (planned, but expanded) and ''VideoGame/HaloReach'' (never planned), which roughly fit into the same "trilogy". In 2012, ''VideoGame/{{Halo 4}}'' was released, which is the beginning of a second ''Halo'' saga, this time with Creator/ThreeFourThreeIndustries as the developers.
* ''VisualNovel/ApolloJusticeAceAttorney'', the fourth game in the ''Franchise/AceAttorney'' series. Shu Takumi had planned the series to be a trilogy, but Capcom called for another game. The protagonist change was due to the fact that the former three games already told all the stories for Phoenix. ''VisualNovel/{{Ace Attorney Investigations|MilesEdgeworth}}'' was meant to be a GaidenGame, with a fifth game in the main series planned. ''Investigations'' ended up getting its own sequel before ''[[VisualNovel/PhoenixWrightAceAttorneyDualDestinies Dual Destinies]]'' was released, though ''Investigations 2'' was [[NoExportForYou Japan-only]].
* Both "''Hitman'' Trilogy", a boxset for the [=PS2=], and "''Hitman'' HD Trilogy", a similar set for the [=PS3=] and 360, actually feature the second, third and fourth entries in the ''VideoGame/{{Hitman}}'' series (''[[VideoGame/Hitman2SilentAssassin Silent Assassin]]'', ''[[VideoGame/HitmanContracts Contracts]]'' and ''[[VideoGame/HitmanBloodMoney Blood Money]]''), skipping the original game in the entirely. The original game in the series, ''VideoGame/HitmanCodename47'', was a PC-exclusive; not to mention ''Contracts'' is, in effect, a remake of it.
* Creator/HideoKojima did not intend to direct any of the ''Franchise/MetalGear'' sequels beyond ''VideoGame/MetalGearSolid''. When he was brought back to direct ''VideoGame/{{Metal Gear Solid 2|SonsOfLiberty}}'', he ended the story with an inconclusive ending and then followed it up with ''VideoGame/{{Metal Gear Solid 3|SnakeEater}}'', a prequel that was marketed as "the final game in the Metal Gear Solid trilogy." However, due to much demand after the open-ended nature of ''Sons of Liberty'', Kojima was brought back again for ''VideoGame/{{Metal Gear Solid 4|GunsOfThePatriots}}'' to tie up all the loose ends and conclude Solid Snake's storyline. Despite this, the ''Metal Gear'' series continues on with a series of prequels starring Big Boss (such as ''VideoGame/MetalGearSolidPortableOps'' and ''VideoGame/MetalGearSolidPeaceWalker'') and ''VideoGame/MetalGearRisingRevengeance'' (a spin-off starring Raiden). Then Kojima started directing ''[[VideoGame/MetalGearSolidVThePhantomPain Metal Gear Solid V: The Phantom Pain]]'', which he is claiming to be the final ''Metal Gear'' game he is directly working on. Kojima has went on record saying that every time he announces a game as the franchise's last, he receives a bunch of death threats from rabid fans, and it's these threats that makes him rethink ending the franchise. The PR collapse of Creator/{{Konami}} appears to have given Kojima the go-ahead from fans to pursue non-''Metal Gear'' ideas.
* After the release of ''VideoGame/LeisureSuitLarry 3: Passionate Patti in Pursuit of the Pulsating Pectorals'', series creator Al Lowe insisted that there wouldn't be a ''Larry [[ExactWords 4]]'', partly thanks to how Lowe essentially wrote himself into a corner without any idea how Larry 3's ending could lead into a sequel. Instead, he chose to [[UnInstallment skip the fourth installment]] (retroactively referred to as ''Leisure Suit Larry 4: The Missing Floppies'') completely and carry on straight into ''Leisure Suit Larry 5: Passionate Patti Does a Little Undercover Work'', where the absence of a fourth game is actually a ''plot point'', and both Larry has amnesia because the BigBad stole the Larry 4 disks, and weaseled out of paying Patti for her work on the score.
* ''Franchise/JakAndDaxter'' was originally intended as a trilogy and thus was written as such: at the end of the third one the Precursors are revealed and the BigBad is defeated. However, a racing spinoff was released a year later, followed by a PSP game with Daxter in the lead, and a [=PS2=] game developed by a different team than original creator Naughty Dog.
* After ''VideoGame/PrinceOfPersiaTheTwoThrones'' wrapped up the trilogy started with ''[[VideoGame/PrinceOfPersiaTheSandsOfTime Sands of Time]]'' and continued with ''[[VideoGame/PrinceOfPersiaWarriorWithin Warrior Within]]'', a handled spin-off titled ''VideoGame/BattlesOfPrinceOfPersia'' came out in the same month then a fourth game in the same continuity, titled ''VideoGame/PrinceOfPersiaTheForgottenSands'', was made in order to capitalize on the release of the ''[[Film/PrinceOfPersiaTheSandsOfTime Sands of Time]]'' movie. A ContinuityReboot had been produced in the intervening years.
* After ''VideoGame/AnotherCenturysEpisode 3: The Final'' came out, many people were hoping for a new "A.C.E." game would be released sometime. Lo and behold, ''Another Century's Episode: R'' for the UsefulNotes/PlayStation3. Note, however, that it is more or less a new continuity as opposed to an actual story continuation. Incidentally, [[WordOfGod Director Terada more or less said]], "I don't know why we called ''A.C.E.3: The Final'' (due to them apparently having every intention of making a new game). So, let's just say that ''A.C.E.3'' was "The Final UsefulNotes/PlayStation2 ''A.C.E.'' game."
* When ''Franchise/{{Fabula Nova Crystallis|FinalFantasy}}'' was conceived, it was originally meant to consist of [[VideoGame/FinalFantasyXIII three]] [[VideoGame/FinalFantasyXV self-contained]] [[VideoGame/FinalFantasyType0 games]] that shared one mythology. Nine years later, and it jumped to six games and about three or four short stories, with possibly more coming along the way.
* The ''VideoGame/{{Onimusha}}'' series was originally conceived as a trilogy, with ''Onimusha 3: Demon Siege'' initially advertised as the final installment of the series. It didn't take long for Capcom to produce a fourth game afterward, with ''Onimusha: Dawn of Dreams'' (aka ''Shin Onimusha'').
* From 1988 to 2015, VideoGame/TheBardsTaleTrilogy was accurately known as The Bard's Tale Trilogy. Then [=InXile=] announced that work had begun on VideoGame/TheBardsTaleIV.
* While there was never really a stated number of games planned in the ''Franchise/FiveNightsAtFreddys'' series, ''VideoGame/FiveNightsAtFreddys3'' seemed like it was being built up as the end of the series, what with the game being set [[TimeSkip more than twenty years after the first (and most recent) game]], featuring only a single surviving animatronic ([[spoiler:[[RealAfterAll maybe]]]]) ,and ending with [[spoiler:[[GreaterScopeVillain the Purple Guy serial killer]] [[LaserGuidedKarma finally being killed off by the spirits of the very children he murdered]] [[CrowningMomentOfHeartwarming and the kids' spirits moving on to the afterlife]]]]. Then [[VideoGame/FiveNightsAtFreddys4 a fourth game]] was confirmed, and was definitively billed as "The Final Chapter"; the game itself supported this, ending by [[spoiler:showing us [[AmbiguousSituation what may be]] [[NoodleIncident the long-speculated]] [[BrainFood Bite of '87]]]]. After this, no further games seemed incoming (aside from the [[VideoGame/FiveNightsAtFreddysWorld largely non-canon spin-off]]), and Scott was absolutely adamant that the series was over and there would be no further sequels...until [[VideoGame/FiveNightsAtFreddysSisterLocation a fifth game was announced]], with Scott explaining on Steam that "[[TrollingCreator I never said I couldn't change my mind.]]"
* A very particular case of this occurs in Rocksteady Studios' ''Videogame/BatmanArkhamSeries''. The series was originally intended to be a trilogy. The first game being ''Videogame/BatmanArkhamAsylum'', the second game being ''Videogame/BatmanArkhamCity'' with the third and final game being ''Videogame/BatmanArkhamKnight''. However, Warner Bros. Montreal (who developed the Wii U port of ''Arkham City'') [[BTeamSequel released a prequel to ''Asylum'']] called ''Videogame/BatmanArkhamOrigins'' between ''City'' and ''Knight'' to hold fans over until ''Knight'' was released. And that's not counting the varius spin-off mobile games or ''Videogame/BatmanArkhamOriginsBlackgate''.
* ''Franchise/{{Kirby}}'' actually manages to invert this (by also using a variation of TwoPartTrilogy): you've got ''VideoGame/KirbysDreamLand'', ''VideoGame/KirbysDreamLand2'', ''VideoGame/KirbysDreamLand3'' and ''VideoGame/Kirby64TheCrystalShards''. The twist is that the trilogy here would be the latter three games, thanks to all of them having several elements in common and an overarching story arc (mostly surrounding EldritchAbomination Dark Matter, who {{Fanon}} named the trilogy after). Thus, the first game ends up being more of a set up for this entire trilogy (and also ''VideoGame/KirbysAdventure'', which is narratively unrelated) instead of part of it.
* Franchise/{{Metroid}}
** The ''VideoGame/MetroidPrimeTrilogy'' was just that for about ten years[[note]]A SpinOff multiplayer-focused game called ''VideoGame/MetroidPrimeHunters'' and a pinball game aside.[[/note]] Then nearly 10 years after ''Prime 3'', Nintendo released another multiplayer spin-off in the form of ''VideoGame/MetroidPrimeFederationForce'', which took place after the events of the original trilogy. Then a year after that, ''VideoGame/MetroidPrime4'' was announced...
** Series co-creator Yoshio Sakamoto originally intended the original ''VideoGame/Metroid1'', ''VideoGame/MetroidIIReturnOfSamus'' and ''VideoGame/SuperMetroid'' to be a trilogy, with ''Super'' being the conclusion of a clear narrative structure (Samus defeats Mother Brain and the Space Pirates, Metroids start becoming a galactic threat so Samus terminates all but one, Space Pirates and a revived Mother Brain steal the last Metroid for their plans and get defeated again). Then VideoGame/MetroidFusion (which is Metroid IV as seen in the title screen) happened, which featured almost none of the previous plot threads, instead having Samus face off against a new threat that justified the existence of the aforementioned Metroids.
* ''Franchise/MegaMan'':
** The ''VideoGame/MegaManBattleNetwork'' series was originally going to end with the third game, but ended up going on for six games (not counting the ''Network Transmission'' and ''Battle Chip Challenge'' spinoff games.)
** The ''VideoGame/MegaManZero'' series and plot threads were supposed to end with the third episode. However, the fate of one specific villain was left unresolved; this spiraled into ''Mega Man Zero 4'' and the true GrandFinale for the series.

[[folder:Web Animation]]
* WebAnimation/TheLazerCollection was originally only going to be three parts long, but when requests for a fourth part were continuously made, [[http://www.youtube.com/watch?v=8aLIP94KBlw the author eventually made it]], but it's a case of StylisticSuck with a subtext of "[[ArtistDisillusionment Now Shut Up]]." There's also a [[http://www.youtube.com/watch?v=Ws4UVguoZjM Part Five]].