Monster of the Week



"T-Bone: "Crud! What is that thing?"

Razor: "Giant monster of the week?""

- from the Swat Kats episode "Unlikely Alloys".

Episodes where the characters fight a villain and the whole story is wrapped up at the end never to be dealt with again. Can be seen as the complete antithesis of a Story Arc. Can also be seen as a Big Bad arc compressed into one episode.

The term (a play on Movie Of The Week) was originally coined by the writing staff of The Outer Limits (1963), which sought to distinguish itself from its biggest competitor, The Twilight Zone, by promising viewers a new monster every episode.

Variations crop up from time to time, though the most genetic term is "Villain of the Week". The 4400 and Smallville for example are sometimes discussed in terms of the "Freak of The Week." Mystery of the Week is the detective series version of this trope.

Sometimes, the monsters get ridiculous, especially in fillers, where they are almost always themed after the plot of the episode. Futari wa Pretty Cure had a giant vacuum cleaner early in its run, for example; Digimon Adventure, a walking garbage dump.

This actually is not a bad thing. Monster of the Week can be used to establish characters or setting. Or perhaps lead to a much bigger Story Arc.

Subtrope of One Shot Character. Often used in collaboration with Adventure Towns, may or may not be Mono-Gender Monsters. See also Robeast, Monster of the Aesop, and Single Specimen Species. Contrast Monster Mash, Rogues Gallery.

Anime

 * Pokémon, Sailor Moon and others in their genres are well-known for this. This trope is very common in some varieties of Anime, and in anime it tends to take an Egregious form that, after watching a few episodes, causes the audience to start asking uncomfortable questions like "Well, why don't the bad guys attack all at once instead of one at a time?" Writers usually stoop to handwaving if they deal with the question at all.
 * Sailor Moon is the most famous of this, with the monsters of the week - at least 80% of the time - also being Mono-Gender Monsters, females in this case. Also, with only one exception (Cienicienta, but not because she's strong, smart or otherwise special, just because the authors wanted to make Usagi's birthday-episode into a two-parter)none of the monsters ever survive the episode they were introduced in. While in some cases the monsters are mindless beasts (Cardians), other times they are shown to be intelligent beings capable of emotion - some not being outright evil even -, which makes it kind of odd how the Sailor Senshi never show any mercy to any of them.
 * Which caused a Dub Induced Plot Hole in the English Macekre of Tokyo Mew Mew. If there's now an "army" of Monsters of the Week, why do we only see one at a time?
 * Both parodied and played straight in Magical Project S, which has Pixy Misa summoning a new "Love-Love Monster" in half of the episodes. The show and its characters are quite aware of both the futility of these creations (as the incantation of "Calling Mistakes" suggests) and their formulaic nature (in an episode where Misa introduces a small army of them, Sammy dryly says "I've seen all those already").
 * Pokémon is well-known for this - some Pokémon get to be the Monster of the Week multiple times. Within the first 24 episodes, Gastly was monster of the week twice: when he was impersonating a statuified woman, and as part of the Lavender Town episode with its evolutions.
 * http://bulbapedia.bulbagarden.net/wiki/Character_of_the_day This Bulbapedia article shows a bunch of characters, even friendly ones, that only appear once in an episode and never come back.
 * Fist of the North Star, moreso in the anime than in the manga, varies between these and genuine story arcs.
 * Voltron, the 1980s paragon of the trope.
 * Mazinger Z is the 1970s paragon, although Dr. Hell sometimes sent two or three at a time as well. Subverted in Mazinkaiser, where Dr. Hell a large number monsters at once against Z and Great Mazinger, and wins.
 * Averted in Shin Mazinger, ironic considering how the original series played out. Dr. Hell never just sends one monster out into battle, and usually has backup plans should his monsters fail.
 * Also averted in the original manga. The monsters gang up on Mazinger more often than not.
 * Samurai Pizza Cats. Lampshaded in one episode, where the Big Cheese introduced the robot menace he'd prepared for this episode with "Monster of the week, please enter and sign in."
 * Nightmare in Kirby of the Stars would provide King Dedede with a new monster with which to try to kill Kirby every episode. Naturally, Dedede is just too cheap to buy more than one at any one time. He did go into debt buying them. Nightmare actually had to send a monster to collect the debt without him realizing (At first). Still was defeated though.
 * Fullmetal Alchemist played this for the first volume before going into the main plot (which it would keep through the entire series); interestingly it was still only one of the chapters of the first volume that didn't affect the story in any way.
 * Likewise, some early episodes of the 2003 anime adaptation had a version of this: if there's a plot important character in the episode we have not seen before, he is probably the Villain Of The Week. The main exception to this rule is Rose. 'Course, a fair share of these episodes turned out to be important to the plot later.
 * Played with and used straight by Rah Xephon. The Dolems mainly show up on a one-a-week basis, although some of them survive their initial appearance and go on to reappear later.
 * Jo Jos Bizarre Adventure arguably boils down to this... except it's "villain for the next month and a half", due to the length of the fights.
 * The series didn't adopt this format until Part 3 began and Stands were introduced, as Parts 1 & 2 were arc based. Interestingly enough, this format helped the popularity of the series, as the fights were unique and the Stand users diverse.
 * It goes back to the arc based format with Part 7/Steel Ball Run
 * For about the first half of Speed Grapher, Suietengu's plan to recapture Kagura is to have his henchmen sic a different Euphoric on Saiga. They never live more than two episodes after being introduced.
 * Early chapters of Yu-Gi-Oh generally featured a "Bully Of The Week." His role was typically to scam or beat up Yugi's friends, at which point Yugi would challenge him to a Cooking Duel or the local equivalent. Most notably, The Rival Kaiba started out like this, but then...
 * The anime based on the manga, and its spin-offs, have a Duelist of the Week who pops up with a new deck gimmick and quirky personality to challenge the hero. With very, very few exceptions, these characters will be defeated in a single episode and will never appear again. If they're lucky, they'll get a two-part episode before they vanish.
 * Every season of Digimon starts out this way as the new characters learn the ropes and the viewers learn the new characters (and in some seasons, new universe.)
 * In the case of Digimon Tamers this is generally held to be what killed the show's american ratings as a true big bad was not introduced until the trip to the digiworld 24 episodes in. Save maybe season 4 where it states that most all monsters are sub races of digimon, save a few, from the start.
 * The anime Dai-Guard hangs a lampshade on this one by having scientists predict that the conditions necessary for the alien giant monster invaders to appear will repeat themselves roughly once every week.
 * Figure 17 plays this completely straight, although there is strong continuity as well. By the end of the series the monsters don't even look different from each other- they just get slightly upgraded powers.
 * This does become less prominent as the plot goes on, however, as emphasis shifts toward Tsubasa and Hikaru's relationship, with some episodes not featuring a Maguar at all, and others being dedicated to particularly large and important, multi-episode fights.
 * Witch Hunter Robin got a new witch every week for the first half. Then things changed rather abruptly...
 * Hell Girl sends one soul to Hell almost every week.
 * Mobile Suit Gundam, while extremely arc-based, still managed to introduce a lot of new enemy mobile suits in a monster-of-the-week fashion.
 * G Gundam is THE best example in Gundam, because this was the entire point behind the series, to draw on the Monster of the Week fan base, or more specifically the robot of the week fanbase, because that was how most robot shows were done prior to Gundam.
 * Played straight in Gao Gai Gar with the Zonders, though taking things in canon time passage it could more likely be considered the "Monster-of-the-half-a-week".
 * Bizenghast did this a lot until book 6.
 * The majority of Martial Arts and Crafts opponents in Ranma 1/2 ended up like this, from the comical and ridiculous (Sentaro Daimonji of the Martial Arts Tea Ceremony School, Picolet Chardin of La Belle France School) to the serious and dramatic (Prince Herb, Ryu Kumon, Saffron.) Then the anime took it above and beyond with outlandish Rivals of the Week who used toys, eggs, calligraphy, or even crepes. Only rivals who had preexisting relationships with the cast, such as Ryouga, Mousse, and Ukyou, were given the chance to stick around and become regular characters.
 * Played straight by Genesis of Aquarion, though at first the monsters were just regular Cherubim Soldiers with some kind of new ability that the team had to find a way to overcome by using lessons from earlier in the episode to unlock a new attack.
 * Bleach started out like this, with Ichigo fighting a different hollow each chapter. Though after Rukia got taken back to Soul Society, it became more Story Arc focused.
 * Inuyasha was this for nearly every episode outside the last anime story arc. Once the manga got past the point of the anime ending, it changed up a little bit.
 * Magical Girl Lyrical Nanoha started out like this, then Fate intervened.
 * Even before that she collected some Jewel Seeds off-screen and several per episode
 * Often overlooked, but Neon Genesis Evangelion also started like this. JesuOtaku's review even calls it the best Monster of the Week show ever.
 * From the 13th angel's attack on though, the trope gets deconstructed. Even though each monster's still gone at the end of the episode that introduced it, the mental scars its attack leaves behind on the main characters remain...and build up over time. In sheer contrast to the typical monster-of-the-week show where the protagonists are usually ready for the next challenge at the start of each new episode, Evangelion's cast is on its last legs by the time the 17th angel kicks the bucket. CUE End of Evangelion.
 * Even the early angels are a minor subversion, as all of the more traditional kaiju-style angels except Matarael (when the standard of "weak" is "you can be hurt by bullets the size of "cars"...) are extremely powerful and durable- in the first episode, Sachiel curb stomps the entire conventional military effortlessly, including what seems to bunker-buster kinetic missile, and tanks a Non Nuclear Nuke with only moderate damage. Zeruel, the most conventionally powerful angel, takes several to the face. And completely ignores them. And every single one of them is capable of
 * Kaze no Stigma. See Shana above.
 * Rosario to Vampire started as a pretty typical Unwanted Harem Monster of the Week manga, but it soon became focused on longer and more serious and involved story arcs.
 * Hokenshitsu no Shinigami plays it completely straight with a few small arcs scattered here and there.
 * Mai-HiME started out this way with the appearance of the Orphans. Then the various Ancient Conspiracies started executing their plans one after another and Nothing Was The Same Anymore.
 * Madoka Magica starts out like this. The format gets dropped before the halfway mark.
 * The Getter Robo series did this a lot. The original, G, Go, and to an extent New all used this trope. Even the crossover movies were Monster of the Week.
 * In Sonic X, the first 26 episodes of the first series had Dr. Eggman's randomly-deployed robots, each one with an E-(insert number here) as their serial number, and the first 11 episodes of the first half of the second series had random Metarex encountered by Sonic and co. along their journey to save the universe from the Metarex.
 * Kekkaishi follows this trope, with a strange new Ayakashi or two attacking the Karasumori site every night. But it's Justified through the actual behavior of the ayakashi, the motives of more dangerous ones, and the steady plans of the Kokuboro.
 * Tengen Toppa Gurren Lagann plays this straight. In the first episode, the Lagann is introduced as well as a minor enemy. Next episode introduces some more mecha, including the Gunzan (later Gurren). Third episode introduces the first actually recurring villain, who's more of an anti-hero. By episode 6, the show actually starts straying becoming more serialized rather than episodic, but maintains its Monster of the Week standard until episode 15, where the MOTW is actually the first Big Bad. The second half reversed this, by having the good guys introduce more and more powerful mecha to kick the enemy's ass, most notably after Team Dai-Gurren goes to space.
 * Kinnikuman first began this way, Monster Extermination arc, before it became the Professional Wrestling series it became famous for.
 * Kimba the White Lion alternates between this trope and a Big Bad Ensemble.
 * Ghost in The Shell Stand Alone Complex has two types of episode: "Stand-Alone" episodes that deal with a one-shot villain or case, and "Complex" episodes that advance the overall Story Arc of the season.
 * With the exception of the series' recurring antagonist Vicious, most Cowboy Bebop episodes centered around a single villain or group of villains that was never heard from again after the end of the episode (some were two-parters).

Comics

 * In the old The Dandy comic strip, Jack Silver, the villianous Captain Zapp had a device known as a Duplicator, which could create a living, breathing copy of any picture that was fed into it. Every week, he would use the strange creatures the machine produced to commit crimes, before being stopped by Jack Silver and his gadget of the week.
 * Many comics tend to have a story with a one-shot villain every now and then. It would be easier to list comic books and comic strips that DON'T utilize the Monster of the Week trope.

Literature

 * The Doc Savage novels are always this  because Doc is so good at what he does.
 * In the books of the Star Wars Expanded Universe, earlier-written ones in particular, the vast majority of villains are only there for the book or trilogy, and books set later or earlier completely forget that these villains ever existed. Odd, considering that they tend to be Imperial forces. The exceptions are Aaron Allston's run on the X Wing Series, which had the campaign against Warlord Zsinj; the Coruscant Nights trilogy, which had one-book guest appearances by Prince Xizor and Aurra Sing; and roughly anything Timothy Zahn writes.
 * The villain usually had a new superweapon, too: The Death Star But Better sums up all of them. The Tarkin was the Second Death Star Before The Writers Knew About The Real Second Death Star, World Devastators are The Death Star But Slow And Productive, the Nightcloak was The Death Star But With Climate Change, Darksaber was The Death Star But Minimalistic, the Eclipse was The Death Star But Also The Executor, the Galaxy Gun was The Death Star But With Really Long Range Nukes, Centerpoint Station was The Death Star But Also Long Range, and the Sun Crusher was The Death Star But God Mode Sue. As you can guess, people who prefer the Death Star as an ultimate weapon hate every single one of them. Particularly since about half of these have characters popping up to exclaim that this superweapon is worse than the Death Star, omg!
 * The Harry Potter series started off with each book covering a fairly stand-alone story. A Story Arc emerged at the end of the third book and gradually overtook the plots of the individual books.
 * The Potter series was always supposed to run to seven books and have an overarching plot, but the first couple of books - particularly the first one - were written so that they could be relatively standalone, just in case they didn't become a runaway multi-zillion-dollar publishing juggernaut and J K Rowling wasn't able to finish the series.
 * This trope is actually Older Than Steam. Journey to The West is lately made up of monster of the week encounters, or in this case monster of the chapter.
 * In the Trixie Belden series, there's almost always a new villain in every book.
 * In the Animorphs series, whenever Visser Three (Big Bad of the series who possesses the same shape-shifting abilities as the titular heroes) would personally participate in a battle, he would do so by assuming the form of a new exotic alien creature that clearly outmatched the Earth animals that the Animorphs themselves had taken the forms of. Subverted by the fact that it is the same character every time, only in a different form.

Live Action TV

 * Red Dwarf goes this way after about the third series.
 * Although, to their credit, the crew is pretty genre-savvy about it, especially in Series 6. (For example, Rimmer explains to one monster that everybody they'd met to that point has tried to kill them.)
 * It also swings the other direction in Series 7 & 8, having the storylines cover multiple episodes. (Although they are still self-contained.)
 * Practically every Super Sentai series (and by extension, every Power Rangers series). There's no point in listing them all, just click the link to see them. Plenty of lampshading. "Just send them all" has in fact been tried before. If it's a small number the Rangers have a hell of a time with them. If it's a large number, Conservation of Ninjitsu kicks in and they go down as easily as Elite Mooks. Except for the time they had to kill Zordon...
 * The X Files almost always had a weekly monster. The X Files is also famous for not quite wrapping up a MOTW and closing with a The End or Is It ending.
 * Unusually, while most fandoms considers MOTWs to be fillers, a large group of The X Files fans considered the weekly monster episodes to be superior to the Myth Arc episodes, especially in later seasons... mostly because the latter were made up as they went along.
 * Fringe started out as primarily a monster of the week show, and it still has them, but now they're either in service of or as a distraction to the Myth Arc.
 * Buffy the Vampire Slayer interspersed Monster of the Week episodes with Story Arc episodes, especially toward the beginning of the season. This became less common in later seasons.
 * Just under half of the episodes of The 4400 were like this. Several episodes would focus on a specific person out of the forty-four hundred people who had disappeared and been returned (and, later on,, what sort of supernatural power they had developed, and a problem they had created (either willingly or otherwise) that would be resolved by the end of the episode. As stated above, it could in this case perhaps be more accurately called something like 'Freak of the Week', as the people in focus weren't always deliberately antagonistic.
 * In SF author David Gerrold's book about writing the Star Trek episode "The Trouble With Tribbles", he recounts seeing the first episode broadcast, which featured a creature that sucked all of the salt out of people's bodies, thereby killing them. He hoped Star Trek wasn't going to turn out to be a Monster of the Week show, which ironically for him, it did.
 * While later series rarely had weekly monsters, Star Trek the Next Generation and especially Star Trek Voyager had stellar anomalies of the week that were always solved by a healthy amount of Techno Babble.
 * The first season of Star Trek the Next Generation started to become a god-like alien of the week show, but fortunately found sturdier footing in subsequent seasons.
 * Doctor Who was originally supposed to be an edutainment program... until the Daleks showed up, whereupon it careened irreversibly into Monster of the Week territory.
 * Notably, the old series was made up of serials, usually three or four parts...making it more like monster of the month. Though, the new series follows this trope straight, while also including more Story Arcs.
 * Supposedly the new series production team will not accept scripts that don't feature a monster of the week.
 * They even lampshade this trope in "The Eleventh Hour", during Matt Smith's epic speech: "Cause you're not the first to have come here, oh here have been so many!"
 * Torchwood...at least, the first two series. After the successful switch to "mini-series focused on a single threat" of Children of Earth, RTD decided to drop the MOTW format altogether.
 * Kolchak the Night Stalker could be considered the ultimate archetype. It was, in fact, even mockingly dismissed by some as "Kolchak's Monster of the Week" when its transfer from a pair of movies to a TV series ended up not quite panning out.
 * The second season of Dark Angel is a good example of this trope.
 * In the Tremors series, monsters of the week were produced by a chemical compound called "Mix Master" which, once released into the valley, randomly scrambled together the DNA of all living things except humans. This created monstrosities ranging from acid-shooting plants to giant shrimp.
 * And one of them was defeated by the resident monster, El Blanco.
 * Almost every episode of Voyage to the Bottom of the Sea, Lost in Space, and several other 60s SF shows produced by Irwin Allen.
 * Common in Toku, especially Kamen Rider, Super Sentai (and by extension, Power Rangers) and the Ultra Series. This isn't terribly surprising, as the action and fights are the main draw of these shows (not that's a bad thing, nor that good storytelling can't go along with that) Indeed, Super Sentai has multiple-stage monster of the week fights, culminating in a robot vs. daikaiju showdown.
 * Power Rangers may well be your average Westerner's introduction to the very concept.
 * The 51 Undead in Kamen Rider Blade are actually in conflict with one another to see which will be the dominant species on Earth (the human Undead was the winner of the last such competition, hence us). It can probably be assumed most of them are simply laying low and gathering their strength at the beginning of the series.
 * Parodied in one episode of Power Rangers Ninja Storm. Lothor tries to send six giant monsters at once against the heroes, only for his device to fail citing a "memory error". His general informs him that they did not pay for the memory upgrade, so they can only enlarge one monster at a time. Lothor curses at this complaining that as future ruler of the world "I need big monsters!'" and settles for enlarging one and making the rest fight while small.
 * Kamen Rider Den-O and Kamen Rider Double are a slight variation on this, as almost every episode is a two-parter (or more); therefore, almost every Monster of the Week actually lasts at least two weeks - and for the former show, that's not counting the ones that were just slightly rebranded and reused, or those.
 * The same can be said for each world's monster race and/or Big Bad in Kamen Rider Decade.
 * At least since Den-O (if not earlier), Kamen Rider series have tended to go with a "Monster of the Fortnight" variation.
 * Two Metal Heroes shows, Choujinki Metalder and Sekai Ninja Sen Jiraiya, avoided this by having several recurring villains instead of a one-off villain per episode.
 * So does Seiun Kamen Machineman.
 * And the Power Rangers rip-offs Superhuman Samurai Syber Squad and Tattooed Teenage Alien Fighters From Beverly Hills.
 * Kaizoku Sentai Gokaiger has a twist on this near the end of the series. On the same episode where the Bigger Bad shows up, he sees the Gokaiger destroy one of his Co-Dragons and says to hell with the whole Monster of the Week thing and spends the next few episodes preparing for a full-scale invasion of Earth, with a frighteningly gigantic fleet of warships. While MotWs still show up in the following episodes, they're completely independent of the Emperor and his plans.
 * The escaped souls from Reaper
 * Those in Brimstone.
 * Supernatural usually has actual monsters, more so in the first two seasons.
 * Heroes is normally entirely serialized, but volume three would often put the arc in the background for a one-off evolved human. Examples include the man who could create wormholes and the Haitian's brother.
 * Big Wolf On Campus. Since it's technically a Monster Mash, that's reasonable enough.
 * Charmed utilized this, although it became less prevalent in later seasons.
 * Primeval, just what will come through the Anomaly this week?
 * Smallville has Meteor Freak of the Week, mutants created by kryptonite. Season 6 also gave us the Phantom Zone escapees-of-the-week. As the series has progressed, it has much more of a Story Arc, but of keeps the Monster of the Week format.
 * Criminal Minds has a new case almost every week (through at least season 3)- usually dealing with the type of people you could call 'monsters'.
 * Angel started by following this trope, but the format was discarded in favor of an arc-based one. Executive Meddling in the fifth season brought it back full circle.
 * The Prisoner had the No. 2 Of The Week, who tried the Scheme Of The Week to attempt to break No. 6.
 * Mystery Science Theater 3000 is this trope.
 * To Catch a Predator.
 * Space: 1999. One of the most common fan complaints about the second season was that it dropped the metaphysical and psychodrama aspects in favour of more Monster of the Week action-oriented stories.
 * Farscape had monsters of the week interspersed with the Story Arc episodes throughout the series.
 * Warehouse 13 revolves around the Artifact of the Week, which can range from purely a MacGuffin all the way up to an actual Monster.
 * Haven revolves around Supernatural Mystery Disaster of the Week. The town seems to attract people who are "troubled" and have supernatural abilities.
 * Lost Tapes on Animal Planet features a different monster tormenting the Point of View character(s) each week.
 * The West Wing does this metaphorically, with Political Crisis Of The Week, caused by Idiot Politician Of The Week (in fact, many episodes are around one week long).
 * Dark Shadows often had season-long arcs like this with one supernatural villain.
 * This was a big part of the first series of Merlin, and the Big Bad only appeared in 4 of the 13 episodes. From series 2 onwards the writers concentrated more on a singular villain (, though occasionally a one-off monster will appear for a Filler episode.
 * Babylon 5 had these from time to time, most often in the first two seasons, with Story Arc episodes mixed in and becoming more common as the show continued. By the third season, such episodes became very rare as the plot began to reach critical mass.
 * Nickelodeon's The Troop is built around this trope.

Tabletop Games

 * Although a different medium, episodic RPG campaigns also fall into this pattern, as gaming groups usually get together to play once a week.

Video Games

 * The monthly Full Moon Shadows that the party fights in Persona 3 at first seem to fall into this category; however, later on, it is revealed that.
 * The true Monster of the Week was typically whichever Tartarus Boss your party was ready to fight on that night's run.
 * A literal example in The World Ends With You for the DS: each week of the Reaper's Game is presided over by a "game master". These are especially powerful reapers who, what do you know, transform into monstrous versions of themselves when you get to fight them.
 * The sets of 8 Robot masters in the Classic Mega Man series easily fall into this. The Game Boy spin-offs do this with the Mega Man Hunters (and Quint) and the Stardroids as well, while the sole Genesis game in the series (Wily Wars) had the Genesis Unit. Then, there's the major villains replacing Dr. Wily...
 * The recent Sonic the Hedgehog games, starting from Sonic Adventure generally have one as the final boss.
 * A large amount of Kirby games' plot follow this, each game being based on one big bad at a time. Of these include Kirby's Adventure with, Kirby Super Star with Dedede, Dyna Blade,  , Metaknight, and   in their respective games, Kirby & the Amazing Mirror with  , Kirby: Canvas Curse with Drawcia, Kirby: Squeak Squad with Daroach (later being  ), Kirbys Epic Yarn with Yin Yarn, Kirby: Mass Attack with Necrodius, and Kirbys Return to Dream Land with.
 * Taken up a notch in the Super Robot Wars franchise. Not only do the heroes have to deal with most (if not all) of the villains and monsters from their respective series (including those mentioned above), but there's also a new latest threat to stop on top of everything else.

Web Comics

 * Gorgeous Princess Creamy Beamy parodies and plays this straight (albeit, in an arc-based way) with its Instant Monsters ,for obvious reasons. So far, three of them have been defeated, with the former two being sentient everyday objects, and the third being human (however, the side effects of the potion on him were unintended).

Web Original

 * The web fiction serial Dimension Heroes often has the Dimensional Guardians fighting a new monster in every chapter, though it must be pointed out the fights still help to advance the story arc.
 * New York Magician: Not many (as there aren't that many stories, all told), but they definitely have this vibe.
 * Quirky Misadventures of Soldine the Cyborg: the first three mini-movies follow this format. The fourth one contains Night of the Living Mooks and a Quirky Miniboss Squad, but the fifth one returns to the classic format.

Western Animation
"Lt. Barf: Captain, we are being hailed. I recommend we go to Red Alert!
 * The various varieties of Scooby Doo usually had a Guy In A Monster Suit Of The Week.
 * Some incarnations even occasionally fought actual monsters!
 * Ben 10 lives on this. Considering the strange and varied varieties of trouble that tend to occur wherever Ben goes, one feels sorry for this kid's hometown if summer vacation ends.
 * Yeah, it gets toasted.
 * Sometimes inverted in a few seasons, where the Monster Of The Week wasn't just what Ben faced, but what he became.
 * Lilo and Stitch The Series: the titular pair try to find a peaceful place for each monster to live.
 * Then there's Rufus from the Kim Possible crossover.
 * The Spectacular Spider Man has Spider-Man fight a Super Villain of the week.
 * Though a lot of these were the result of the machinations of one or more of the show's three Big Bads - Tombstone, Doc Ock, or, rather than isolated encounters.
 * What's really interesting is the show's justification for why there are so many supervillains running around: The Big Bads had them created to keep Spider-Man busy and thus unable to interfere with their standard criminal operations.
 * Megas XLR practically lives off this, along with a fair bit of lampshade hanging. "Cool. Lets go see what kinda monster I get to beat up this week!"
 * The various ghosts of both The Real Ghostbusters & Extreme Ghostbusters fit neatly into this trope.
 * So do the ghosts of Filmations Ghostbusters.
 * On Swat Kats, this phenomenon also cropped up as the "Missile of the Week" used to deal with the current problem at hand.
 * Aqua Teen Hunger Force usually follows this rule, with the monster somehow spawning out of Shake or Carl's short-sighted actions or out of nowhere.
 * When not facing their Rogues Gallery, the Powerpuff Girls mostly just take on different monsters.
 * Spoofed in Sev Trek: Puss in Boots (an Australian parody of Star Trek the Next Generation).

Captain Pinchhard: We haven't even met them! Isn't that a little premature?

Lt. Barf: Every week we encounter aliens who try to destroy or take over the ship. It would save a lot of time if we assumed the worst now."


 * Martin Morning demonstrates this, with the odd twist of the protagonist being the new monster each episode.
 * The whole point of Martin Mystery.
 * An episode of Batman the Animated Series, "The Underdwellers", spotlighted a villain called the Sewer King who never appeared again. He was sufficiently creepy for a Batman villain, but it's just as well he never returned, since he was really only good for one story (that is, showcasing the evils of child slavery).
 * Regular Show seems to be establishing itself as one of these; but you'd probably prefer to call it "Weird Crap of the Week."
 * Courage faces this all of the time in Courage the Cowardly Dog.
 * The Mutraddi Beasts of Sym Bionic Titan.
 * Underdog often fights one of these (usually an alien) when he isn't fighting Simon Bar Sinister or Riff Raff.
 * Teen Titans have a couple of villains who are Monster of the Week (Besides of the ones where ). Some villains were lucky to have two appearances.
 * The Divinos of Combo Ninos.
 * Dr Claw of Inspector Gadget had a new special MAD agent almost every week, who would never be seen again after the episode they appeared in. Gadget and The Gadgetinis did the same, but also had some one-time villains with no connection to M.A.D. or Dr. Claw whatsoever.