Clock Roaches

"You brief humans think of time — if you think of it at all — as a natural thing. Ubiquitous. Inevitable. You are blind little fish in the waters of a vast, deep cave. There are... others, who see time differently. When it is meddled with, they notice."

— Castle Heterodyne, Girl Genius

Time flies like an arrow; fruit flies like a banana; Clock Roaches like causality.

Time, like Death, hates being tampered with. It uses things like Hitler's Time Travel Exemption Act to stop changes to itself, and the Butterfly of Doom to exact roundabout retribution, but sometimes the determined chrono-criminal can find ways around these defenses.

In cases like these, time likes to get its hands dirty and ensure a less ironic and more graphic end to these pesky revisionist historians with the help of Clock Roaches.

Clock Roaches are time's clean-up service. They eat and destroy people and things that directly threaten time with a Temporal Paradox. Like roaches, they "eat up" the crumbs and mistakes of time travelers, and if they directly make nuisances of themselves, eat them as well. Also like roaches, you can never kill them all, nor hope to survive against their mindless fury for long. At best, you can delay them, and hope to fix whatever it is you've messed up and marked you as Roach-Chow.

In a way, Clock Roaches can also be seen as time's immune system. In a scenario where you inflict damage to the timeline by way of your meddling, you are the threat, and so these entities come out of the woodwork en masse to ensure you are stopped.

The concept of Clock Roaches probably stems from the difficulty in representing the threat of creating a time paradox. It's hard to show that the whole of existence is about to slip down the timey-wimey chaotic vortex of fate, and that it's definitely bad. It's much easier to write when anybody who dares to transverse the spacetime continuum gets eaten by an Eldritch Abomination. You could call them Chronos' Vengeance.

One of the possible results of a Time Crash. Compare to the Necro Non Sequitur, a gratuitous and Rube Goldberg-y way for time to deal with interlopers. Not to be confused with the Butterfly of Doom, in which the insect punishing the time traveler for interfering with the natural progression of events does so by dying, when it's not just a metaphor to begin with. Time Police is similar, but is where creatures like this are part of a formal organization. Similar are creatures out for those who mess with space. You may look for examples in Hyperspace Is a Scary Place.

Not related to the insectoid Dungeons & Dragons construct of the same name; they, and any other roaches made of clockwork, are a kind of Clockwork Creature. However, it is possible for Clock Roaches to be a Clockwork Creature. Has absolutely nothing to do with the Thackery T. Lambshead Cabinet of Curiosities.

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Examples:

Anime and Manga

• EDENS ZERO: Chronophages are space monsters that pass through the universe and devour the time of planets, rewinding them to an earlier state and leaving alternate histories in their place. They are attracted to planets where someone has "gone against the flow of time" since they can sense time fluctuations and home in on them like a beacon, though it's not necessarily a guarantee one will appear.
• In Eureka Seven AO, the Secrets describe themselves as this. When communication is established with the head of one Japan recovered, it claims that its creation is part of nature and that its sole mission is to eradicate the foreign Scub Coral. However, they are more intelligent than most Clock Roaches, being willing to negotiate on the point as long as it meets their goals. Christophe Blanc makes a contract with them to eliminate the Quartz using the Quartz Gun as a proxy, since the Secrets know it's capable of beating them. This way both parties win: no Scub Bursts and no Quartz.
• Rave Master: This is the origin and purpose of the Endless; to destroy the world created by someone's tampering with time. It can only be killed by Etherion (specifically stated to be the power to create something from nothing, thereby justifying the paradox) and even then, only under very specific conditions. It is also explained that using the Star Memory to modify the past to prevent the current Endless' birth will only create a second Endless.

Comic Books

• Aztec Ace includes "Doxie-Glitches", which are giant monsters that show up when a paradox threatens time and fix it by killing everyone in the vicinity.
• The Time Vortex Leech from Doctor Who (Titan) is a rare benevolent one, whose interference saves the lives of Jones and everyone on Datastore 8.
• In Doctor Who: Four Doctors mini-series the Tenth and Twelfth Doctors touching summons the Reapers, covered below under Live-Action TV.
• One More Day: During his astral jaunt through the past, Spider-Man runs afoul of beings called Nightwalkers. Monstrous creatures that live on the edges of time and space, ready to pounce on anyone attempting to tamper with destiny.
• As travelling through the time-stream into Superman Family #200, Supergirl gets stalked and assailed by a Time Beast, an ageless demonic monster that preys on time-travellers.
• Time Beavers, a graphic novel by Timothy Truman, postulates that a race of time-sensitive beavers monitor the Dam of Time, which separates the relative order of the universe we know from utter chaos. The Dam is composed of items of considerable historical importance, such as "Fat Man" and "Little Boy". Several such items are stolen by the Beavers' mortal enemies, a shape-changing species of sentient rats who want chaos to run rampant.
• Ultimate Fantastic Four: The spider-shaped Argiopes, who would eat any time travel-created doubles to avoid paradoxes.
• Wonder Woman (1942): Diana, Steve and Etta are temporarily locked in a Stable Time Loop and prevented from altering it by a giant Clockwork Creature which keeps violently separating them and tweaking their memories (at least Steve and Etta's) every time they do anything that might endanger the loop remaining stable.

Fan Works

• The "agent-in-place" from Harry Potter and the Nightmares of Futures Past is a somewhat less omnivorous version of this trope. We don't know a lot about him, but he is apparently at Hogwarts, knows of the original timeline, and is working behind the scenes to ensure that certain events (such as Ginny getting possessed by the Diary Horcrux) come to pass in spite of Harry's manipulations. Later, however, we find out that his efforts to redirect the timeline are not due to any knowledge of the future that was: Lucius Malfoy contacted his son when no evidence of the Chamber of Secrets being reopened surfaced thanks to Harry intercepting the diary, and tasked Draco with finding the diary and returning it to Ginny Weasley. Ultimately, he was successful, only for the plan to meet its end the same way as in canon.
• The Apoptosis in Light, Darkness and Paradox are a threat to everyone who enters the Tartarus (passages between worlds), doing their best to kill them.
• In Nightmares Are Tragic, the Cosmic Concepts combined forces to eradicate The World That Was Lost because it threatened to crash the continuum with its acausal paradoxes. Cosmic Luna and the G3 Pinkie Pie directly dueled as part of the resultant battle; Luna barely won.
• In The Parselmouth of Gryffindor, Luna Lovegood believes in the existence of Clockroaches and asks Hermione if she's seen any after she gets her Time-Turner. According to her, they're also known as Time-Tigers or Langoliers, and they eat time-travellers with onions and hot sauce.
• Pony POV Series:
  • The Blank Wolf in Shining Armor's arc erases things that aren't supposed to exist, such as anachronisms brought into being by a non-God Reality Warper. The good news? It's after the Big Bad, Makarov/the Shadow of Chernobull, and is implied to be one of the ways Shining can stop him. The bad news? Shining is Immune to Fate due to being a temporal distortion, meaning it's after him. However, it obeys the Gods, so having Cadence nearby gives him protection. By the time it resurrects after being killed at the end of the arc, Shining's existence is stable, thus it's on the heroes side against Discord and company's endgame, though unfortunately it's still a puppy and thus far weaker than it was in the Shining Armor Arc.
  • The Cosmic Concepts themselves play this role — in extreme emergencies (when paradox threatens the whole continuum), the Alicorns and Draconequi will combine forces to erase the offending timeline. This is what happened to the G3 universe.

Films — Animation

• In Hello World, it is technically diving into a digital past rather than actual time travel, but the homeostatic system programmes do the same thing in that they purge any anomalies trying to tamper with the recorded history.

Films — Live-Action

• In the Final Destination movies, Death himself manages to act as a Clock Roach. The protagonists have a vision of their own gruesome demise and save themselves along with a group of their friends, and the remainder of the movie consists of Death finding increasingly gruesome, sadistic, and physically impossible ways of correcting the error. This is eventually subverted, when it's revealed in The Final Destination that showing the protagonists a vision of their death is part of Death's plan! Turns out, the victims were never meant to die there and the "corrections" to the error are actually their proper fated deaths to begin with — Death just really likes to play with his food.

Literature

• In the Buffyverse collection of short stories Tales of the Slayer, Volume 2, the short story Again by Jane Espenson has these after Buffy, Willow, and Xander are returned to their high-school selves. The roaches in this case manifest as mobile shadows that attach themselves to things they find in the wrong time, causing excruciating pain as they (presumably) eat them. They appear to be somewhat physical, as Buffy manages to cut one off of her arm, cutting her arm in the process.
• The Eschaton Series: The invention of Faster-Than-Light Travel brings with it the ability to travel through time. This in turn leads to the potential for whole new strategies of warfare and unpleasant weapons taking advantage of the ability to meddle with the past... but it is all prevented by a particularly powerful AI which uses its own (particularly effective) causality violation devices to smite any would-be temporal saboteurs with godlike amounts of overkill.
  "I am the Eschaton. I am not your god. I am descended from you, and exist in your future. Thou shalt not violate causality within my historic light cone. Or else."
• The Hounds of Tindalos chase down time travellers; the only way to hold them off is to eliminate all angles in the immediate area, since they can only travel through these. Note that they're not portrayed as necessary or helpful; they just are.
• Humanity Has Declined offers an inversion: collapsed temporal paradoxes turn into time paradogs.
• The Langoliers in the book and movie of that title by Stephen King. In the story, several airline passengers find themselves trapped in a moment in the past, which is slowly fading and winding down as the present time moves further and further away, until the moment is completely eaten by the titular Langoliers.
  [Bob is watching the Langoliers eat up the entire airport]
  Bob Jenkins: Now we know, don't we?
  Laurel Stevenson: Know what? We know what?
  Bob Jenkins: We know what happens to today when it becomes yesterday. It waits for them. It waits for them, the timekeepers of eternity. Always following behind, cleaning up the mess in the most efficient way possible: by eating it!
• The Sisters Grimm: The pink eraser things in book ten, since the book they are in was magically linked to the time of fairy tales, and any changes change history, so Mr. Editor guy has his pink erasers eat everything and he resets the story.
• In Vasily Golovachev's Time of Troubles series, messing with time attracted a race of Eldritch Abominations called "chronosurgeons" who threatened to erase the Universe (and all its parallel branches) from the point of the Big Bang itself. Note that those abominations had no motivation of "protecting causality" (their motives, like those of any good little eldritch abominations, were inscrutable), but merely trying to mess with time drew their attention.

Live-Action TV

• Arrowverse:
  • A speedster carelessly meddling with the past risks summoning a Time Wraith to seek out and destroy the meddler. When Barry asks Thawne why he has never encountered them before in The Flash (2014), he is told that he's been incredibly lucky. Besides, at most, he's affected one day before (when stopping Mardon and Savage). Zoom's careless use of a speedster's time travel abilities ultimately catches up to him when Barry lures the Time Wraiths out and gives him too much of a beating to escape. The Time Wraiths age Zoom nearly into a skeleton and then drag him away screaming to a Fate Worse than Death.
  • It's implied that Time Wraiths are former speedsters, who were caught by other Time Wraiths for messing around with time travel and turned into one of them.
  • Non-speedster time travelers don't seem to bother the Wraiths, as demonstrated in Legends of Tomorrow. Come season two, however, we see exactly what happened to Zoom — he's been turned into the Black Flash and is now hunting Reverse-Flash for being a walking time paradox. It ultimately catches him and completely disintegrates him.
  • The only known weapon that can kill a Time Wraith is a high-intensity low-frequency sonic attack. Luckily, Hartley Rathaway (a.k.a. the Pied Piper) knows a thing or two about sound.
• Doctor Who:
  • "The Time Monster" has the Chronovores, which are similar enough to the Reapers (giant winged reptile-like gargoyle creatures that eat people's timelines) that they may as well be considered a related critter. It's worth mentioning that the Chronovores were fleshed out in a novel by Paul Cornell, who later wrote "Father's Day". Some fans speculate that he wanted to feature Chronovores in "Father's Day" below, but was prevented by some sort of legal issue. Given how we know the Doctor just often makes things up sometimes, they could even be the same creatures, just under a different name that he made for them this time.
  • The Reapers, Flying Killer Time Gargoyles from "Father's Day". The Ninth Doctor describes them in terms similar to white blood cells cleansing infections and repairing damage to the body — when a paradox is triggered, they clean up the "wound" by erasing everything inside it. "Before" the Time War, the Gallifreyans kept paradoxes in order in a much less destructive way, but now they're gone.
• Eerie, Indiana: The garbage men in "The Lost Hour". To them, the garbage is Marshall, since he's not supposed to be there and then.
• Legion (2017): David's attempt to go back in time and prevent his own possession by the Shadow King draws the attention of time-dwelling monsters that Switch calls "demons" and "blue cats". Among other things, they force Lenny to see her unborn daughter age and die.
• Loki (2021): Alioth is a dark sentient cloud that lives at the Void at the end of time and devours anyone and anything on its way. It had been found and tamed by He Who Remains during the Multiversal War, and was used to eliminate anyone who the Time Variance Authority judged as guilty of interfering with the Sacred Timeline by creating alternate universes.
• Sapphire and Steel: You're never quite sure what the agents of time look like, but you definitely don't want to hang around and find out.
• The Twilight Zone (1985): In "A Matter of Minutes", the Wrights, a young married couple, wake up one day to the sounds of construction and find that a construction crew is tearing down and rebuilding time.

Radio

• In the Big Finish Doctor Who audio plays, they have Vortisaurs, creatures who live in the Time Vortex and are attracted to temporal anomalies. They're usually vicious, but the Doctor manages to tame one.

Tabletop Games

• In Continuum, the players themselves are Time Police. However, if the players fail, Clock Roaches known as Inheritors show up to clean things up, and the game makes it clear that you do not want to get in their way.
• The Dark Eye has Satinav, a deity, who is responsible to keep the timeline intact as a punishment for being the first trying to meddle with time travel. Even gods and demons rarely dare to mess with time for this reason.
• Demon: The Descent: Among the many, many possible designations for Angels is "Time Hunter", which denotes an angel charged with slipping between different timestreams and temporal splinters in order to eliminate quantum ghosts and other temporally-displaced individuals who might tangle up the timelines. Unusually for this trope, they're also charged with eliminating individuals in order to create temporal splinters or timeline divergences as well as eliminating those who inadvertently get caught up in temporal anomalies.
• Dungeons & Dragons:
  • The 3rd edition of the game have the Inevitables, constructs born in Mechanus (the plane of absolute law) to enforce certain laws, both natural and invented. One kind of Inevitable, known as the Quaruts, maintain the sanctity of time and space itself.
  • The Clockroach itself, on the other hand, does not embody this trope, being instead a clockwork-based construct that happens to look like a giant cockroach and so is given a Punny Name.
  • The Obscure AD&D 2nd Edition splatbook Chronomancer featured several different species that can function as these. While they generally will leave people alone, they can be provoked. One sure way of getting their attention is to attempt to meet yourself via Time Travel — Never the Selves Shall Meet is a physical law of the universe, and attempting to violate it makes temporal causality painful for anything that lives in the timestream, so increasingly powerful clockroaches will attack the attempted offender in an attempt to put an end to whatever is trying to violate the rule.
• Exalted has the pattern spiders, the gods that maintain the Loom of Fate, and are basically responsible for the laws of physics. Bend the aforementioned laws too much, and you'll incur their displeasure in the form of a Pattern Bite, which is basically a spider bite, except that the spider is a giant mechanical god-spider responsible for maintaining natural law, and what it bites is not you, but your thread in the Loom of Fate, causing all kinds of unpleasant effects. So not much like a spider bite at all, really.
• Mage: The Ascension: Wrinkle is the Paradox Spirit that shows up to deal with people who have pushed their luck one too many times in tampering with how things should be, especially temporally. If the mage apologizes for what they did and agrees that they shouldn't have done it, then Wrinkle does the actual work of rewinding events to the point where the offending Reality Warper can try something else. If not (or if the mage fails to find a suitably non-reality-disrupting alternative after several attempts), then he traps the mage in a time pocket until they give in... or in some cases, rumor has it, he rewrites time so that the offender was never born. He is the most powerful Paradox spirit in Mage by an order of magnitude.
• Pathfinder: There is a considerable variety of creatures who will come hunting for people who mess around with time, either to directly protect the timestream or because they're attracted to the side effects of the tampering. The first category includes time flayers, time dimensionals (which are not so much creatures as pieces of the Dimension of Time calved off to deal with problems), time dragons and bythos aeons. The second counts hounds of Tindalos and immense spider-like creatures called time crawlers, which feed on energy from time paradoxes but will happily munch on the paradox-makers as well.
• In TimeWatch (for the GUMSHOE system), there are literal Clock Roaches, in that there are human-sized roaches from the distant (possible) future who come to the past to ensure their own timeline comes to pass.

Video Games

• Blinx: The Time Sweeper: All the monsters except the main antagonists are a result of a colossal Time Crash. The plot revolves around eradicating them. This makes the Time Sweepers, who work for a time factory and ensure the product works as intended, more of the correcting function than the monsters, however.
• Inverted in the game Braid. In World 1-1, you have to outrun a giant flaming wall before it catches up to you. However, because time is already reversed in World 1 (using the rewind mechanic makes it progress forward), it represents the future that hasn't occurred yet being obliterated, with Tim and the Princess running back towards the present.
• As a result of Magus' actions, Lavos absorbs Schala and becomes the Time Devourer, the ultimate Clock Roach, who, rather than going after Crono and his friends, unmakes all existence. That is the entire plot of Chrono Cross. You can stop it, but not by simply defeating the Time Devourer; it'll just reproduce from another reality and the new one will replace the old one. You have to play a song that unites all reality, leaving the Time Devourer no copies of itself to regenerate from.
• In Devil Survivor 2, a major theme of the game is averting the pre-ordained deaths of the main characters, manipulating the Akashic Records to suit your whims, and generally giving a big ol' middle finger to the Divine Order of the Universe. Record Breaker has the Divine Order of the Universe respond to said defiance with the Triangulum, a group of Starfish Aliens even bigger and meaner than the Septentriones. The Triangulum has one goal: obliterate the irritating "malware" that keeps messing with the Records, so that the natural order can get back on track. In the event that even the Triangulum fail, the Divine Order of the Universe sends its 100% invincible shards down to personally deal with the main characters only for an error that even they can't comprehend to render them killable.
• The Whispers in Final Fantasy VII Remake are essentially this, although the heroes don't find about their purpose before they're gone: essentially, Sephiroth and Aerith both remember the events of the original game, and the former is manipulating everyone to create a timeline where he was never defeated while also making sure the heroes destroy the Whispers. After all, he can't have his own timeline if the Whispers are still around to protect the original events.
• In the Final Fantasy XI expansion "Wings of the Goddess", The avatar Atomos is a mindless being that eats 'dispensable' time, including the memories anybody might have of alternative timelines that have become endangered due to the intervention of time travelers. All of this ends up dumped in the Walk of Echoes, a graveyard for everything that might have been.
• In Life Is Strange, the tornado that destroys Arcadia Bay on Friday is likely somehow connected to Max developing time travel powers on Monday and making changes to the timeline. Near the end of the game, Max's friend Warren theorizes that her time travel is responsible for the storm, making the storm an example of this trope under this theory. Shortly afterwards, the player, through Max, can decide to attempt to prevent the storm by going back in time to Monday and let events happen without time travel. Doing this will result in the death of Chloe, Max's best friend and love interest. Alternatively, Max can let the storm happen to ensure Chloe's survival. Though the storm doesn't happen in the ending where Chloe dies, the cause of the storm and the source of Max's powers are left unexplained. This has led some fans to theorize that other forces may be at work behind the storm.
• The Apoptosis in Monster Girl Quest! Paradox RPG attack anyone who tries traveling between parallel worlds, and when a parallel world diverges too much from the timeline of the original world, they destroy that world.
• NEO: The World Ends with You has the Soul Pulvis, a massive swarm of bird Noise made from the souls of people from timelines that were undone by the protagonist's time travel powers; as such, it grows stronger and more numerous every time said power is used. Its creation was engineered by the Big Bad to erase Shibuya from existence, and the only ways to beat it are a literal Deus ex Machina or a complicated plan involving multiple protagonists' powers being used to weaponize the souls of the main timeline against it.
• Prince of Persia: Warrior Within has the Dahaka, a guardian of time that hunts the Prince in order to restore time to its original flow. It's implied that whenever someone changes the past, a Dahaka shows up to deal with it — the first one was created when the Prince tampered with time, and a second comes up to deal with his second attempt to fix his own mistake in the game. If you get the Golden Ending, you kill the Dahaka, and Kaileena, the Empress of Time sails away with you. Thus the Sands of Time are not created in the past. (They get created when Kaileena is killed.)
• In Raidou Kuzunoha vs. The Soulless Army, Rasputin the Mad Monk (actually a Ridiculously Human Robot built in his image) was originally employed by some kind of future entity as part of an attempt to erase the timeline Raidou lives in (for example, the year is Taisho 20, but the Real Life Taisho era only lasted 15 years). He blows off the mission once he realizes it's a pretty sweet time to live in. It is implied allowing Raidou to change stuff stamped out the Crapsack World that is the timeline of Shin Megami Tensei I and Shin Megami Tensei II.
• Singularity has mutants, creatures, and strange plants that were spawned from time travel shenanigans.
• In Super Robot Wars, Ingram Pliskin and his clone Cobray are secretly these. According to Ingram in an exposition, every universe is given only one (hence why Cobray's powers didn't manifest until after Ingram was dead), and that their job is to protect causality by deleting from existence any force that threatens it.
• TimeShift: The protagonist fits this role, as there is apparently a danger of the Alternate Timeline "colliding" with our own if the Big Bad isn't stopped. What exactly this would mean is not explored, suffice it to say that would be bad.
• The upcoming game Titanic: A Space Between involves a time traveler going back to the sinking of the Titanic, which incurs the wrath of several cosmic horrors.
• The Time Devourers in We Need to go Deeper appear after the use of a time portal to begin the New Game Plus, acting as a new obstacle to pursue the player's submarine.
• World of Warcraft:
  • The Bronze Dragonflight are a heroic version of this; their hired help (the players) are their Time Police.
  • The Infinite Dragonflight that attempts to change the timeline is universally villainous—only two out of four of their attempts even try to have a weak Hitler's Time Travel Exemption Act excuse (which is explained to make the current situation worse anyway), the rest being outright villainy.
  • Their goals have been muddied even further with confirmation in Wrath and Cataclysm that the Infinites are a corrupted future version of the Bronzes. While still Clock Dragons, they're using their ability to modify time instead, hence the greater danger they pose than most people tampering with time.

Webcomics

• The Adventures of Dr. McNinja has some sort of... bear-octopus-unicorn creatures^note They are, in fact, quite literal one-eyed, one-horned, flying, purple, people-eaters. that attack wayward time travelers.
• Girl Genius has these things. Clock Eldritch Abominations might be more accurate. And the last time someone tried this stunt, The Dreaded Dreen showed up. Kjarl Thotep, an interdimensional entity that's taken up residence here, explicitly states Dreen only show up when a given time catastrophe is really, really bad.
  Castle Heterodyne: This stopping time foolishness-Robur Heterodyne discovered something like it three hundred years ago. Oh, yes. And yet, the Heterodynes-they who fear nothing-turned their backs on this power. You brief humans think of time-if you think of it at all-as a natural thing. Ubiquitous. Inevitable. You are blind little fish in the waters of a vast, deep cave. There are… others who see time differently. When it is meddled with, they notice.
• Timeclones and altered timelines are not welcome in Homestuck. Any given Hero has an alpha timeline; mostly this only matters to the Hero whose purview is Time. Either way, any deviation from the alpha timeline, or extraneous instance of a given hero, caused by time travel shenanigans is doomed to die eventually, in some unfortunate and contrived manner if the universe can't scrounge up a good one. Although in the pre-scratch kids' case, any session that does not deal with it is destroyed by The Tumor, a giant bomb buried in the center of the Battlefield.

Web Originals

• The Angry Video Game Nerd: The Berstein Bear during the 2016 Halloween episode.
• The Creepypasta The Farnsworth Experiment deals with a group of scientists who managed to upset a nest of Clock Roaches while researching time travel.
• The Nostalgia Critic dedicated an entire episode to the aforementioned The Langoliers.

Western Animation

• Similar to the Final Destination movies is the rule that chronal doubles in the Futurama universe always meet with some sort of fatal accident in order to keep them from cluttering up the time-stream... So of course, the sudden appearance of an army of time-duplicated Benders at the end of Bender's Big Score results in all of the clones self-destructing at once, and a huge rip in space-time leading to another dimension, handily setting up the plot of The Beast with a Billion Backs.
• In the Generator Rex episode "A Brief History of Time", Van Kleiss thinks he's being hunted by one of these. As it turns out, it's actually Breach, who has transformed into a Negative Space Wedgie that's attracted to him like a magnet — and destroys everything in its wake.
• Hilda has the titular character run afoul of Time Worms. Creatures that exist to devour wayward time travel duplicates, with the only way to stop them being setting history to its correct path.
• In the Justice League Action episode "Time Out", a time fissure results in the release of what Booster Gold calls "antibodies", flying manta-like creatures that essentially pop up wherever time is disrupted and "fix the problem" by killing everything in sight.
• Rick and Morty:
  • After pausing time to clean up a house party at the end of the previous season, season 2 introduces the time police in the form of Shleemypants, a fourth-dimensional being who looks like a Langolier with a living gun who intends to arrest Rick, Morty, and Summer for messing with time. Ironically he ends up changing time when he's defeated by Rick, goes back for help, and comes back to the wrong time period to beat the living crap out of the wrong elderly scientist: after being beaten severely for no reason and screamed at to "not mess with time", said scientist defiantly remarks "I vill mess vith time" and begins writing the Theory of Relativity on the board.
  • Randomly beating up people in history seems to be Shleemypant's modus operandi, as he does it again in season 4 to correct the time stream after time has been messed up by (stay with me) a horde of time-traveling sufficiently advanced alien snakes. Shleemypants decides the best way to fix it is to get a buddy, travel back in time and find a prehistoric snake using a tool, and beat the complete man-shit out of it. It works.
• Vector Prime of Transformers: Cybertron is shown in the Expanded Universe to have this sort of job, though he's far more personable than most examples and not nearly as unstoppable. The giant, all-consuming rift that shows up in the Time Wars arc of the UK comic fulfills the trope more.

Real Life

• Some interpretations of quantum mechanics imply that quantum effects act like Clock Roaches to prevent the formation of time paradoxes by negating attempts at creating them.

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