->''[[foldercontrol]]

[[folder: The pattern has repeated itself more times than you can fathom. Organic civilizations rise, evolve, advance, and at the apex of their glory they are extinguished. ]]
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-->--''VideoGame/{{Mass Effect|1}}''

A killer is on the loose. Sometimes the killer is a person, but more often it's some sort of supernatural monster. Many people... dozens sometimes, and sometimes even hundreds... of people have fallen to this fiend. No one's noticed because the killer only comes out to play every few years, or every few decades, or even ''[[ExtyYearsFromNow every few centuries]]''. Regardless of the time involved, no one has connected this long string of victims.

At least, no one has put two-and-two together until now. Our [[IntrepidReporter intrepid]] hero is the only one clever or lucky enough to connect the dots. Now if he can only convince [[ReasonableAuthorityFigure someone]] that the same killer who murdered those prostitutes a hundred years ago is the same killer murdering prostitutes today without being accused of being the killer and left unprotected in a jail cell.

A specific type of ViciousCycle. May overlap with HorrorDoesntSettleForSimpleTuesday. If the killer is a supernatural being, it is often a case of AsLongAsThereIsEvil.

If this happens monthly, it may be MenstrualMenace or {{Lunacy}}. ([[OurWerewolvesAreDifferent Werewolves]] are especially prone to the latter.) A particularly regular CometOfDoom could also count.

And this is a DeathTrope, so expect '''''UNMARKED SPOILERS!'''''

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!!Examples:

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[[folder:Anime and Manga]]
* In [[Anime/FullmetalAlchemist the 2003 anime version]] of ''Manga/FullmetalAlchemist'', Hohenheim and Dante kill people every so often to use as surrogate bodies for their souls. Dante is attempting to start a new and more destructive cycle by [[spoiler:devastating countries with knowledge of Philosopher's Stones so they will create one she can steal]].
* In ''VisualNovel/HigurashiNoNakuKoroNi'', the curse of Oyashiro-sama kills 2 people every year. And it's always right around the town's big cotton-drifting festival, and only 1 body is found, and it's always someone related to the dam project.
* In ''Anime/LogHorizon'', the "Return of the Goblin King" was a bi-annual event in the game ''Elder Tale'' where the various Goblin tribes would unite under a King. The players knew in advance when this would happen, so they would coordinate and plan for it, easily finishing the event when it rolled around. But when ''Elder Tale'' became reality, the players were so focused on adjusting to living in the new world that they forget about the event, and when the Goblin King is crowned, a massive invasion by Goblin armies results... an invasion that could have real, lethal consequences since it is no longer a game.
[[/folder]]

[[folder:Film]]
* The Creeper in ''Film/JeepersCreepers'' emerges from hibernation every 23 years and feeds for 23 days.
* The ''Evil'' in ''Film/TheFifthElement'' is said to return every 5,000 years.
* The League of Shadows in ''Film/BatmanBegins''.
* The {{Kaiju}} in ''Film/PacificRim'' are attacking on a schedule so regular that the defense force has a countdown clock accurate to the second. The intervals are getting smaller, though, and the movie starts with a prediction that they'll soon be sending more than one at a time. [[spoiler:Which is, of course, proven true.]]
* The BadSanta Dutch movie "Sint" deals with the regularly scheduled attack of the ghost of a SinisterMinister (which is the origin of the Sintkerlaas / SantaClaus myth) and his [[IAmAHumanitarian flesh-eating]] [[FullFrontalAssault naked]] barbarian "elves" every 25 years on Christmas. [[spoiler: At the end of the movie, we find out that the [[PoliceAreUseless police]] and [[GovernmentConspiracy government]] are aware of these attacks and seriously think there is nothing that can be done other than keep things under wraps and pray for the best, even letting one of the heroes (a CowboyCop [[TheScrooge Scrooge]] that hated Christmas because of being a survivor of a previous attack) take [[DeceasedFallGuyGambit the posthumous fall]] for the movie's events.]]
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[[folder:Literature]]
* The vampires in PeterWatts's novel ''Literature/{{Blindsight}}'' were like this until humans invented architecture, which killed them off. ItMakesSenseInContext.
* Creator/StephenKing's ''{{IT}}'' does this, with Pennywise only killing every twenty-seven years.
* In ''Literature/AmericanGods'' by Neil Gaiman, Shadow discovers that the disappearance of teenagers over the course of several years in a small town are actually sacrifices to an ancient tribal god that resides in the town. Not even the people in the town know about the [[TownWithADarkSecret dark secret]].
* Appears in a fairly benign fashion in ''Discworld/CarpeJugulum'' . Every few years the old Count de Magpyr would arise from the grave, probably kidnap some young woman who looked good in a nightdress, then be killed. This went on for long enough and was generally harmless enough that no one really minded.
** It's implied that "kidnap" may have been a bit of face saving on the part of the "kidnapee". The Old Count was, by most accounts, rather charming when he wanted to be.
* In ''Literature/TheWheelOfTime'', [[TheDragon Ishamael]] briefly escapes [[SealedEvilInACan his prison]] once every thousand years. The first time resulted in the Trolloc Wars, and the second time resulted in the collapse of Artur Hawkwing's empire. On an even grander scale, the ends of the two Ages we're privy to involved a climactic showdown with the local {{Satan}} {{Expy}}; presumably the ends of the other five Ages are similarly dramatic.
* David Weber's ''Literature/EmpireFromTheAshes'' series has a similar premise to Mass Effect below. Every 50-100,000 odd years, a huge fleet sweeps th galaxy, exterminating every sapient species it finds. The last interstellar human empire, of which the population of Earth is an offshoot, was aware of this fact, and built an enormous fleet to stop them. Unfortunately for Earth, we're on the closest edge of human space to the fleet, they're coming again, and the Imperium is nowhere to be seen.
* In the Dragonlance series, the gods agree that there must always be a balance between good and evil, and therefore Takhisis MUST be released at some point in history to allow the balance to reassert itself or there could be another cataclysm like the Kingpriest of Istar brought about.
* In ForgottenRealms, it is much the same as Dragonlance. The Overgod Ao exists to preserve the balance only, not to take sides against good and evil. That is why in the Avatar Trilogy he chooses an insane human to be the god of various evil things and a good mage to be the goddess of magic. That bites him in the ass in the end, because magic is meant to be part of the balance, and therefore neutral for EVERYONE, so the goddess is forced to change. The insane god of murder eventually gets his comeuppance too. He murders so many gods that even the Overgod can't say he's 'just doing his job' anymore. He upset the balance so badly that the only solution was imprisonment in his own pocket plane for one thousand years. [[SarcasmMode Yep, being alone with his own mind for one thousand years will DEFINITELY help his sanity.]]
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[[folder:Live-Action TV]]
* ''Series/{{Supernatural}}'' has this happen whenever they investigate a murder, to the point that it's now standard operating procedure for the Winchesters to look for such patterns.
* Eugene Victor Tooms from ''TheXFiles'' episodes "Squeeze" and "Tooms" comes out of hibernation every 30 years to feed on human livers, a process which has made him functionally immortal.
* In the ''Series/{{Star Trek|The Original Series}}: TOS'' episode "The Wolf in the Fold", an alien energy being called "Redjac" frames Scotty for murder. Turns out the immortal killer has been going from planet to planet, killing people, for centuries. At one point it was Jack the Ripper.
* Penn, the serial-killing Puritan vampire sired by ''Series/{{Angel}}'', went on murder sprees every ten years or so.
** Also from ''Angel'', the {{Mayincatec}} demon from "The Cautionary Tale of [[MaskedLuchador Numero Cinco]]" returns to eat the heart of heroes every fifty years.
** Angel himself did this [[JekyllAndHyde when he was evil]]. While Angelus cheerfully tortured and killed people all year round, apparently he thought Valentine's Day was special and every February 14th made sure he did something ''really'' evil and [[EvilIsPetty petty]] to mark the occasion.
* The second ''KolchakTheNightStalker'' movie ''The Night Strangler'' (1973). Once every 21 years for the last century, an alchemist strangles several women and extracts their spinal fluid to use in an elixir of immortality.
* The ''Series/{{Torchwood}}'' episode "Countrycide" has a group of villagers deliberately kidnap the sort of people who would go missing in the countryside every ten years for a [[ImAHumanitarian harvest]].
* In ''Series/BuffyTheVampireSlayer'', Hansel and Gretel were really a demon that appeared every so often as a pair of murdered children to provoke witch hunts.
* In the ''Series/{{CSI}}'' episode "Sweet Jane," a serial-killing dentist (played with chilling effect by the great Ned Beatty)started killing when he was in his late teens, and only gets "the urge" every ten years or so. He doesn't get caught until he's in his seventies. The length of time between murders is one reason it took so long for the police to catch him.
* In ''Series/{{Dexter}}'', Special Agent Lundy becomes convinced that a pattern of murders repeated across the country is one person. The rampage has been going on every few months for over 30 years. The entire fourth season is centered around this mystery.
* In the ''Series/CriminalMinds'' episode ''Bloodline'' a [[TheFamilyThatSlaysTogether family]] [[spoiler: (which later turns out to only be one branch of a whole network of families)]] follows a tradition of selecting a random family that has a daughter. Then they break into the selected family's house, kill the parents and abduct the girl, in order to raise her as a wife for their son. By traveling all over the country and presumably only killing once [[spoiler: per family]] per generation, they've managed to remain undetected for at least a hundred years.
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[[folder:Tabletop Games]]
* In {{Ravenloft}}, committing six murders over six days with the ''fang of the nosferatu'' grants the wielder NighInvulnerability and no aging for thirteen years. The darklord of Zherisia has been using it regularly for over a century as of the adventure ''Hour of the Knife''.
* ''TabletopGame/MagicTheGathering'': From the original ''Mirrodin'' Block, Memnarch's [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=46708 "Levelers"]], designed to keep the plane's civilizations from growing too powerful by [[ExactlyWhatItSaysOnTheTin leveling them]] every century.
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[[folder:Video Games]]
* In ''VideoGame/FinalFantasyX'', the [[{{Kaiju}} giant monster]] Sin always returns to wreak destruction on the planet Spira a few years after it's 'destroyed'. But in this case, the people of the world know of it (a giant killer space whale is sorta hard to miss, after all), and its cycle of rebirth is well known. What they ''don't'' know is that [[spoiler:the very act of 'killing' it is what causes it to be reborn, as whichever Final Aeon is used becomes Sin in its place.]]
* {{Dracula}} of ''Franchise/{{Castlevania}}'' naturally returns every 100 years, AsLongAsThereIsEvil in the hearts of man. This assumes no one tries to resurrect him in an evil ritual, or there isn't a [[VideoGame/CastlevaniaPortraitOfRuin massive surge of evil]] at the time (and someone to do the proper actions for the deed).
** The "hundred year cycle" is broken by the time of ''VideoGame/CastlevaniaAriaOfSorrow'', instead replaced with a cycle of solar eclipses.
* [[EldritchAbomination The Reapers]] from ''Franchise/MassEffect'' return roughly every 50,000 years or so to wipe out all advanced life in the galaxy before returning to dark space as they have for at least 37 million years. Nobody puts two and two together because they go out of their way to make sure no definitive proof of their existence is left after their centuries-long genocides. Luckily for the galaxy, the [[BenevolentPrecursors last guys to get the treatment]] [[FlingALightIntoTheFuture left a little something special for the future civilizations]]...
** [[AbusivePrecursors The Reapers are also shown to shape the galaxy to fit this method]]. For instance, [[LostTechnology they seeded the galaxy with enough technology to accelerate the development of space-faring civilizations]], but not enough that the civilizations can begin to develop weapons or defenses that might stand up to a Reaper.
** Most importantly, [[spoiler:they created the mass relay network, and due to its extent and ease of use, it inevitably becomes the main faster-than-light method of travel for evolving civilizations. This ensures the colonies will all be within reach of the Reapers when it's time to destroy them.]]
* In ''StarControl 3'', it is revealed that the Orz are scouts for a being/race from another dimension that comes to devour all sentient life in our galaxy every time it reaches critical mass. Naturally the most intelligent guys from the last cycle left clues (then devolved themselves just below sentience).
* In ''Videogame/{{Okami}}'', the dread serpent Orochi demands a human sacrifice (VirginSacrifice is implied but not stated) every year at Kamiki Village's Full Moon Festival. Unlike other examples, everyone knows exactly when it will happen and where the poor maidens go to be killed, but no one dares stand up to Orochi.
* Taken to ridiculous extremes in ''VideoGame/HalfMinuteHero''. Each mission of the main story involves an evil lord who casts a spell that will destroy the world in 30 seconds. In the endgame content the villain returns like clockwork every 100 years, each time giving the main character 30 seconds to save the world.
[[/folder]]

[[folder:Western Animation]]
* [[WesternAnimation/PinkyAndTheBrain The same thing we do every night]]! [[spoiler: Try to take over the world!]]
* In ''Disney/{{Hercules}}'', a group of centaurs would attack a nearby village every Sunday. The villagers got used to the raids to the point of treating them as an UnusuallyUninterestingSight. Then the centaurs' leadership was taken over by a warlord who suggested that they break out of the pattern.
* ''WesternAnimation/AvatarTheLastAirbender''
** If you're not from the Fire Nation, Sozin's Comet counts (it comes approximately every 100 years to magnify Firebenders' power and allow them to do more world-dominating damage than usual).
** If you ''are'' from the Fire Nation, there's the Day of Black Sun, a solar eclipse that strips Firebenders of their powers and makes the Fire Nation vulnerable to attack.
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[[folder:Real Life]]
* Not evil as such, but some locusts and other species of insects do this, remaining dormant for a regularly scheduled period of years (always a prime number) and then emerging in huge numbers to mate, lay eggs, and die. If you're really unlucky, they'll be eating while they do this.
** According to The Other Wiki, the Rocky Mountain locust caused terrible devestation to farming efforts in the American midwest in the later half of the 19th century, until the species mysteriously went extinct. It is theorized that humans broke the cycle by inadvertently destroying all the locust's eggs during one of their (the locusts) dormant periods when they (humans) plowed up the ground where the locusts nested in order to plant crops.
* El Niņo, a regular reversal of weather patterns, which can lead to crop failures and famines in certain parts of the world. Dynastic changes and rebellions in China has a tendency to happen on El Niņo years.
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