Trapped in Another World

 LF2DzAQYw68 ""Toto, I have a feeling we're not in Kansas anymore.""

- Dorothy Gale, The Wizard of Oz

A standard plot/Myth Arc for Speculative Fiction: The Ordinary High School Student, frequently his friends, and sometimes his enemies are all transported (often summoned) to another world—distant planet, a Magical Land, Alternate Universe, the past, The Future—where they find they have an important role to play in Events of Significance that are occurring at the same time as (or sometimes because of) their arrival. Usually there is no hope of their finding a means to return home until after the great threat facing them has been defeated; occasionally, they will then question whether they even want to leave (they typically do).

In the early 2000s a variation on this concept began appearing, starting in Japanese media with the first installments of the .hack franchise—that of players trapped in their MMORPGs. Although these "worlds" are often actually virtual simulations the effect is much the same, and sometimes the danger can be even greater. This has proven a popular subtrope, to the point that by late 2014 it arguably qualifies as a genre of its own (called Isekai in Japanese fan-parlance and "transmigrator story" in media of Korean or Chinese origin), with examples such as Sword Art Online and Log Horizon exploring and expanding on the concept. The main alternate take on Isekai is that the protagonist dies and gets reincarnated into another world (usually a fantasy or wuxia-themed RPG-like one in male-oriented works, Otome Games or romance novels in female-oriented ones) with their memories and personality intact. (By the way, some people take the literal translation of Isekai, "Another world", as a rather strict requirement, and thus exclude works where characters' minds are inserted into a video game with technology while they are technically still alive and on Earth).

This type of plot device is extremely popular in crossover fanfiction.

A blend of Fish Out of Water and Failure Is the Only Option, with a large dash of heroism. The inverse of Alien Among Us. Often overlaps with Down the Rabbit Hole, You Can't Go Home Again, and I Choose to Stay. If it's the hero's job to bring back the trapped person, it's an Orphean Rescue. May involve Fantastic Romance. May result from a Folgers Crossover. In literary circles, this is often referred to as a Portal Fantasy.

For specific worlds to travel to see Another Dimension and Otherworld Tropes.

Anime and Manga

 * Magical Shopping Arcade Abenobashi: After the first episode, the heroes fall from world to world, each one based on one of the main characters' geekish hobbies.
 * Aura Battler Dunbine, but then it twists it by having all the people from the other world get sent to Earth.
 * The Wings of Rean, made by the same director and in the same setting, is like-wise, although both are more like "people from Earth get sent to another world who then get sent back to Earth and then get stuck there with otherworlders."
 * This also occurs in Super Robot Wars Compact and Super Robot Wars Alpha with the Argama and its crew, who meet the Dunbine characters there.
 * Blood Lad: Not only is Fuyumi Yanagi a human girl trapped in Hell, she dies in it. And the story is then focused on bringing her back to life.
 * The first, fourth, and sixth seasons of Digimon, and a Story Arc in the middle of the third season.
 * Parallel Trouble Adventure Dual
 * El-Hazard: The Magnificent World: When Ifurita sends Makoto to El-Hazard, and accidentally sends along Fujisawa-sensei, Jinnai and Nanami as well.
 * In Fullmetal Alchemist, the first Homunculus is trapped in the human world and in a flask, which he admits sucks, but he's not that bothered about it.
 * In Fullmetal Alchemist: Conqueror of Shamballa, in an inversion, they are trapped in our world, having originated from another, where magic alchemy is fairly commonplace.
 * Fushigi Yuugi: Miaka and Yui get pulled into a mythical world inside a magical book.
 * Kyou Kara Maou: Though Yuuri isn't really trapped, and can go back and forth between the two worlds with relative ease, he only considers himself trapped when he returns to his native world.
 * Jura Tripper sends no less than 15 people to a planet where humans and dinosaurs co-exist.
 * Magic Knight Rayearth does this to Hikaru, Fuu and Umi.
 * Monster Rancher
 * The Twelve Kingdoms: Youko Nakajima and her friends Ikuya Asano and Yuuka Sugimoto get dropped in the middle of a mostly hostile fantasy world by a White-Haired Pretty Boy/Mysterious Protector. Though, this is apparently common enough for the locals to coin terms ("Kaikyaku" for Japanese people, "sankyaku" for Chinese) and for the government to have a regular policy in dealing with them. For example, The Kingdom of En has a standard naturalization/citizenship process while Kou just tries to round them up and kill them.
 * And before they came in, a farm girl named Suzu was spirited away from the Meiji era and thrown in the same world. Only to go through much heartbreak.
 * Shoryu, the king of En, also was from Japan. In fact, he was a daimyo or feudal lord whose clan was wiped away in the feudal wars. Having become a Fallen Prince, he accepted to become the King of En.
 * Vision of Escaflowne: A rare example of the other world not being treated as another dimension of some sort—they get stuck on an invisible moon, just past the actual one.
 * Season 3 of Yu-Gi-Oh! GX
 * Now and Then, Here and There (aka Ima Soku Ni Iru Boku). This is an exceptional example of this trope because the creators threw out every convention associated with it from episode 1. Shu sees a strange young girl sitting on a smokestack on his way home from school and goes to meet her. As he is introducing himself he and the girl are attacked by people teleporting in from the distant future in pursuit of that girl. True to the genre Shu picks up a stick and fights to defend the girl. He immediately gets his ass handed to him and both he and the girl are dragged forward billions of years where Earth is a dying desert planet orbiting a sun in the early stages of nova. What follows is a relentless thirteen episode trip through the ninth ring of Hell.
 * Kagome from Inuyasha in the first few episodes. Afterward she's able to go between the other world and her own at will.
 * Subversion: Yukinari from Girls Bravo gets trapped on the planet Seirun in the first episode, but is returned to Earth in the same episode.
 * From Far Away
 * Spider Riders plays with this, Hunter never seems to feel like he's "trapped" in the Inner World. The reason he ended up there in the first place is because he went looking for it!
 * The Mahou Sensei Negima manga has Negi and a group of his student get stuck in the Magic World after
 * Those Who Hunt Elves do so because the elves hold the secret to the spell that will return them to Earth.
 * In The Familiar of Zero, the male protagonist is "accidentally" summoned to another world by the female protagonist in a summoning ceremony.
 * Long-running shoujo series Red River and Ouke No Monshou both feature this trope, a girl from modern day trapped in Ancient Mesopotamia and Ancient Egypt respectively.
 * The Sorcerer's Curse arc of Mythic Quest revolves around everyone in the world being deposited in the dimension created by the MMORPG Mythic Quest with no way out and no extra lives.
 * This happens to Tsukasa from .hack//Sign, with a computer game.
 * In There Beyond the Beyond, protagonist Futaba is taken to a fantasy world due to a case of Mistaken Identity. In order to get back home, he needs to reunite the Amaranthine with her master.
 * Ginta of MAR actually makes the willing decision to go to the other world (after wordlessly making sure his love interest is unable to follow him), and once there is overjoyed to find that getting back isn't going to be easy.
 * Kyon in The Disappearance of Haruhi Suzumiya. Subverted in the fact that.
 * Uninhabited Planet Survive! involves 7 Ordinary High School Students and a robot cat getting stuck on another planet.
 * Melo Melo Melonpan has a short story about a gamer sucked into a Dragon Quest expy much like Genki, then (being that this is an H-Manga) he realizes the NPCs don't have Barbie Doll Anatomy and functionally robotic humans that repeat the same programmed lines ad nauseum he proceeds to have sex with every woman in the kingdom including, but not limited to his in-game "mother," potential party member, a nun, a mother right in front of her son in the town square as she walks, and the queen and princess while completely ignoring the mission. Unfortunately or fortunately for him, his real-life mother thinks he merely left the game on again, turning it off and stranding him there forever.
 * In the setup to Overlord, Momonga is one of the sparse remaining fans of a failing MMORPG; when the devs decide to shut the servers down, he decided to stay online until that occurs, but when it does, he finds himself trapped in a fantasy world that resembles the game, in the body of the lich-like character he used. Seeing as he has no family, friends, or anything else in the real world except a boring white collar job, he doesn't make much effort to finding his way home, and it seems he isn't the only victim of this odd transition.
 * Spirited Away: Chihiro Ogino is trapped in the spirit world. Her family walks into a theme park after her dad takes a 'shortcut', and her parents eat food which turns them into pigs. She becomes trapped when the sun falls and the way out is flooded. The film is notable for using almost none of the typical tropes associated with this plot, instead choosing to focus on character development and relationships.
 * The Cat Returns features a hilarious version of the trope. The protagonist Haru is being carried off to the Cat Kingdom and forced to marry a cat, turning into a Catgirl in the process. She's trapped in the Cat Kingdom all right, but fear not, as other cats — Muta and the Baron from the Cat Bureau — are there to help Haru escape.

Comic Books

 * The tag line of the late Steve Gerber's Marvel comic Howard the Duck was "Trapped in a world he never made!" A native of a Talking Animal world of anthropomorhic ducks, Howard fell through a portal and wound up in Another Dimension—namely, the Marvel Universe version of Cleveland, Ohio.
 * Cross Gen's Negation featured a Ragtag Bunch of Misfits trapped in an alternate universe that did not obey the laws of physics. At least one character started out convinced that it was All Just a Dream.
 * This is the raison d'etre for the Marvel comic series The Exiles. Superpowered beings lost from their dimension, world hop until they get to go home.
 * This was Adam Strange's origin in DC Comics. An archeologist who accidentally discovered an alien transport system, Adam became the number one hero of the planet Rann. His problem was that the Zeta beams which teleport him are only temporary and he has started a family on Rann. He has since been able to stay there permanently, but on occasion where he finds himself on Earth and this trope applies there.
 * Mike Grell's DCU comic The Warlord, a deliberate homage to Pellucidar (in setting) and Barsoom (in tone).

Fan Works

 * Let us just say that Fanfic writers love this trope when they do crossovers, self-inserts, etc. It's a very common trope for Fan Fiction. So much so that it has its own Fan Nickname: "Bamfing".
 * An excellent example of this trope in fanfic is With Strings Attached. The Fab Four are scooped up and dropped on the planet C'hou with nothing except the clothes on their backs and some musical instruments; they're terrified out of their minds and have absolutely no idea why they're there. The reader knows they're there as the subjects of an alien undergraduate psychology experiment (at least initially, until the experiment breaks down), but the four don't learn anything for around a month, when they're told that they've been brought over and equipped to fetch the three pieces of a statue to end a continent-sized curse. The quest is legitimate in context, but was assigned to them after they were equipped.
 * With the adaptation of The Lord of the Rings to film, a veritable storm of mediocre to terrible fanfics appeared about girls falling into Middle-earth. Nearly every single one of these girls are Mary Sues in the guise of an Ordinary High School Student, who are more often that not self-inserts that fall in love with Legolas or, less commonly, Aragorn, as Wish Fulfillment for their authors.
 * Occasionally seen in Undocumented Features — for instance, Utena and the other Cephirans in Symphony of the Sword, and Princess Azula later in the Future Imperfect cycle. Enough enter the UF 'verse that there's actually a guidebook — So You've Just Arrived From A Parallel Universe — published in-universe for them, and in at least one polity in the current era — the Republic of Zeta Cygni — cops on the beat have a standard procedure for dealing with them.
 * Twister from the 1990s-vintage ur-Mega Crossover Twisted Path by Darren "Twister" Steffler is not so much trapped in another world as trapped outside of his home world. He/she (It Makes Sense In Context) eventually acquires the ability to move from world to world, but outside of an incomplete story of uncertain canonicity he never makes it back to the timeline where he was born and raised.
 * Legion from Legion's Quest by Ed Becerra could return to his home timeline but won't lest he lead a horde of god-level threats and Eldritch Abominations there. He instead travels from timeline to timeline, trying to grow strong enough to fight them off before he can even consider returning home.
 * Douglas Sangnoir of Drunkard's Walk, like Twister, is trapped in a series of worlds after being kicked out of his native timeline by enemy action. Nothing stops him from going back, except his only means of traveling between all the possibilities in an infinity of universes is untargeted and random.  Well, that, and several gods have told him he has something to accomplish on his travels, and until he does it, they won't send him back home — even to pay a debt one owes him.
 * Inverting the trope is the premise of the entire shared world My Apartment Manager is not an Isekai Character; instead of the self-inserts going to a fictional world, fictional characters come to the shared world. (Hence the implied meaning behind the title: "My apartment manager is not an isekai character, but everybody else in the apartment building is!")

Film

 * Tron: In an attempt to recover evidence that proves Corrupt Corporate Executive / Cracker Ed Dillinger stole his promotion-worthy ideas for video games, Playful Hacker Kevin Flynn ends up physically digitized into Cyberspace by the Deus Est Machina Master Control Program.
 * This has become the franchise staple, as no protagonist gets digitized voluntarily. In Tron 2.0 Jet Bradley gets digitized by Ma3a in a desperate act of self-preservation. Later, . In Tron: Legacy Sam learns the hard way that you shouldn't press "yes" at every pop-up dialog on somebody else's system.
 * Oh, it's so much more bone-headed than that: Sam looks at the last command given to the computer before him (i.e. Flynn's last command) and then tells the computer to run it again. Then again, he apparently did inherit his old man's copious forethought...
 * Labyrinth
 * Enchanted.
 * Merlin
 * The Wizard of Oz
 * Narnia
 * The Neverending Story
 * Alice in Wonderland
 * David Lynch's Inland Empire
 * In Cool World, both Frank and Jack are transported to the titular world.

Literature

 * L. Frank Baum's The Wonderful Wizard of Oz. Most of the first six-odd "Oz" books fell under this trope, with Dorothy finding her way back to Oz only to get back to Kansas by the last page, though eventually Baum just had Dorothy (along with Uncle Henry, Aunt Em, and Toto) move to Oz full-time and continue her adventures there. Whenever another human came to Oz from the outside world after that point, they generally ended up staying (Oz after the wicked witches died and Ozma took the throne being a much more utopian place to live, occasional monsters and baddies notwithstanding). It's implied even pre-Ozma that Oz was a much better place to live than Kansas; and Dorothy only kept going back home because she didn't want to ditch her family. That certainly is her only reason after meeting Ozma, with whom she has a very close relationship.
 * The John Carter of Mars series and the Pellucidar series, by Edgar Rice Burroughs.
 * Lewis Carroll's Alice in Wonderland: One of the earliest and most famous versions of this trope and a template for many later stories.
 * Stephen R. Donaldson is fond of this one. It's the premise of:
 * The Chronicles of Thomas Covenant.
 * Mordant's Need: a woman from the 'real world' is trapped in a Fantasy realm where any reflective surface can access another universe.
 * Neverwhere by Neil Gaiman.
 * In Diana Wynne Jones's Charmed Life this is what happens to Janet and her eight analogues in the other worlds in Series Twelve - when Gwendolen escapes from World 12A, she pulls Janet in from World 12B, and so on all around the circuit.  Janet's parents don't notice the change.
 * Guy Gavriel Kay's The Fionavar Tapestry. The five main characters are transported to Fionavar at the beginning of the first book, The Summer Tree and return to their own world at the end of it; then they go back near the beginning of the second book, The Wandering Fire, and stay there through to the end of the third, The Longest Road, when their various fates are resolved. At the end of the trilogy the score stands with  The books are somewhat eclectic.
 * In Stephen King's The Dark Tower, Roland draws his ka-tet from New York City at various points in time to his own world.
 * C. S. Lewis's The Lion, The Witch, and The Wardrobe; a slight twist here is that the characters age significantly during their stay in Narnia, then are returned to their original ages when they leave. The other Narnia books tend to follow this pattern as well, except for The Horse and His Boy.
 * Un Lun Dun by China Mieville
 * In Alan Dean Foster's Spellsinger series, the main character is summoned by a powerful wizard looking for another powerful wizard. Apparently, an engineer would be the closest thing to the alternate world's wizards. Unfortunately, the summoning spell latched on to the main character's job title: sanitation engineer. Fortunately, he does turn out to have magical abilities in that world.
 * Similarly, in L. E. Modesitt Jr's Spellsong Cycle, the main character is summoned because of her skills as a singer. The author seems to like this trope, since in his Recluce Saga series this combined with Lost Colony is used in two books.
 * The Merchant Princes Series, by Charles Stross.
 * In Mark Twain's A Connecticut Yankee in King Arthur's Court, the aforementioned Connecticut Yankee, Hank Morgan, gets whacked over the head with a crowbar and finds himself in Arthurian England.
 * Actually inversed with The Princess 99, where an alien biker chick from the future finds herself stuck in the human world in the 1920s.
 * Barbara Hambly's Darwath series: Ingold could bring Gil and Rudy back to Earth any time, at the risk of the Dark learning how it's done and coming to eat Los Angeles.
 * Joel Rosenberg's Guardians of the Flame series depicts a small group of college students who get magically transported to the world of their fantasy roleplaying campaign. They struggle to escape
 * The Summoning series by fantasy/romance author Robin D. Owens focuses on a group of Colorado women who are called, one by one, to be champions of the world of Amee. Unique in that any Earth-native brought to Amee will eventually face the Snap ... a point where Earth tries to call the person back, and will unless she has made a stronger commitment to Amee.
 * The premise of The Inverted World is that a city has somehow become transported to a bizarre alternate world, one where they must constantly move forwards in order to survive.
 * Land of Oblivion has its Kid Hero protagonists transported to a place where dead children have their afterlife. The place is not all rosy, though, and they have to.
 * Coraline is somewhat a Deconstruction of this concept, as
 * Dave Duncan's The Great Game explains why characters in this situation tend to become heroes—anyone who's in a different dimension than the one they were born in can absorb Mana. At low levels, this just makes them really, really charismatic. If they There are hazards to this, however ...
 * In Warrior Cats,
 * In Daughter of the Falcon, Jessie, a girl from our world is trapped in Mysteria, a Magical Land. This is then Deconstructed as
 * In Sergey Lukyanenko's The Boy and The Darkness, the protagonist is a teenager named Danny who travels to another world covered in perpetual darkness. His way home is almost immediately destroyed. . At the end, Danny gets the chance to go home by wishing for one thing from a godlike being..
 * H. Beam Piper's Lord Kalvan of Otherwhen was once a Pennsylvania state policeman named Calvin Morrison, who was accidentally dropped off in a parallel universe where the Aryans went east instead of west, and conquered North America. As it happens, he lands in a small kingdom that's about to be wiped out by the Corrupt Church that holds a monopoly on the secret of gunpowder manufacture...and he knows how to make gunpowder.
 * Grand Central Arena: The experimental starship Holy Grail and its crew find themselves stuck in The Arena, a vast extrauniversal construct, and can't get back home unless they learn how the rules of The Arena work. Unlike most of the other examples, this one is SF, not fantasy, although there is Sufficiently Advanced tech involved.
 * In Teresa Frohock's Miserere an Autumn Tale, going through the Veil to the Woerld means you can never return to Earth.
 * Enchantment by Orson Scott Card.
 * A Wizard in Rhyme.
 * In A Dirge for Prester John, getting into or out of Pentexore is impossible most of the year, effectively trapping anyone who isn't keeping a strict eye on the Rimal.

Live-Action TV

 * Life On Mars: Though we are Left Hanging as to the true nature of the world; is it Time Travel, an alternate reality, or All Just a Dream? And the sequel Ashes to Ashes.
 * Doctor Who: Rose is trapped in a parallel world,
 * A staple premise of series by Sid and Marty Krofft such as The Lost Saucer, Liddsville, Dr Shrinker, Land of the Lost and HR Puffnstuff.
 * Farscape, where Crichton travels through a wormhole to another part of the universe. His overriding goal for most of the series is to get back to Earth...but when he finally does, he leaves very shortly to go back to the other side of the universe. He later returns and makes it impossible for himself to ever go back in order to protect Earth from the bad guys. John, being John, makes many a reference to The Wizard of Oz in relation to his situation. Title of the episode when they really go to Earth: Kansas.
 * The Time Tunnel - two guys trapped in the past (or occasionally the future).
 * Likewise Quantum Leap
 * The Sterling family in the short-lived series Otherworld.
 * Fat Guy Stuck in Internet is about...a fat computer programer trapped in a surreal cyberspace world.
 * Season 1 of Stargate Atlantis—trapped in the Pegasus Galaxy. This is a variation, because the expedition went to Atlantis knowing full well that they might be stranded there.
 * Stargate Infinity—generally trapped away from Earth and the rest of polite galactic society since their iris codes had been revoked.
 * According to early reports, Stargate Universe is taking this tack as well, stranding the heroes on a space ship headed away from known space
 * They are billions of lightyears away from home and if they could control the ship, the journey would take millions of years. They don't have enough power to dial home and dialing IN from the Milky Way needs a special kind of planet but even then, a small mistake in the calculations WILL cut off the supply line permanently via an Earthshattering Kaboom. This happened in the first episode. Later on, it was revealed that the Lucian Alliance found another planet which the SGC attempted to capture; the Alliance however activated the gate prematurely and this planet blew up as well.
 * Star Trek: Voyager—Trapped in the Delta Quadrant.
 * The island of Lost is sufficiently weird that a case could be made.
 * This happens a lot in the Polish/Australian children's series Spellbinder. Paul gets trapped in the Spellbinder universe, Kathy's family gets trapped in the Land of the Dragon Lord, and Mek and Kathy end up trapped in first the Land of the Immortals and then the Land of the Moloch.
 * In Kyle XY, Josh frequently suggests that Kyle is an alien from another world (although this is later subverted when Kyle's true origins are revealled).
 * In season 3 of Fringe, Olivia is trapped a good deal of the time in another universe, an alternate universe. Peter has been trapped in another universe since he was seven years old.

Video Games

 * Dragon Quest III. Combines alternate dimension with Time Travel, as . This also means that 90% of the game is the prologue.
 * Final Fantasy Tactics Advance. And its sequel.
 * Final Fantasy X.
 * Another World, where the story starts with the protagonist accidentally teleported to an alien world.
 * The Dig involves a group of astronauts who get transported to an alien world.
 * Outcast, with a lot of Time Travel causing the issue.
 * The Pokémon Mystery Dungeon games combine this your character being a human stranded in a world full of other talking Pokemon, transformed into a Pokemon themselves.
 * Played with in the Explorers games, where
 * Nox, with the protagonist's character class affecting (among other things) whether or not he returns from the titular fantasy world back to present-day Earth, or stays there.
 * ZanZarah is a subversion: its protagonist Amy is tricked into traveling to another world (which she is supposed to save) but among the first things she finds there is a magical rune that teleports her back to London. Not that she wants to, since her home is a very dull place, constituting one bleak location among hundreds found in the game.
 * This is the premise of Myst, in which the player stumbles across a mysterious series of worlds after accidentally using a Linking Book. Actually, even if you win the game, you don't get to go home. In the opening of the sequel, Riven, Atrus promises that, if all goes well, he might be able to send the player home. Subverted in Myst III and IV, where the player willfully returns to visit Atrus.
 * It's implied at the end of Riven that when Atrus, he's leaving the player with both a way home and a means to visit him. This was before D'ni turned out to be.
 * In Brutal Legend, roadie Eddie Riggs winds up in a world based on Heavy Metal album covers after injuring himself and spilling blood on his belt buckle. Turns out that it's a really important belt buckle.
 * The Avatar of the later games of the Ultima series (from IV onward) is explicitly stated to be a normal human from Earth before he or she is summoned over. According to Word of God, this is true of the first three games as well.
 * In Half Life, Gordon Freeman is trapped in a hellish alien dimension until he can take down the.
 * In the first Persona game, the party ends up spending a good deal of the game in an alternate version of their city.
 * Harukanaru Toki no Naka de has the main character and her two friends summoned into a place that looks quite like Kyoto in the Heian period.
 * The expanded backstory of the Mario franchise indicates that Mario and Luigi are actually from Brooklyn, and accidentally ended up in the Mushroom Kingdom. It's unclear, however, whether they can't get home or just choose to stay.
 * The Hero of Albion ends up trapped on another planet, when losing contact with the factory ship he came with. After he saves the world from the ship's on-board supercomputer that was programmed to destroy it, he essentially traps the crew.
 * Jak and Daxter are sent through a rift gate to Haven City at the beginning of Jak 2 and lack any means to leave.
 * Brad, the player's character in Curse of Enchantia, is boy from our dimension who has been kidnapped to a fantasy world ruled by an evil witch and now has find a way back.
 * The plot of The Longest Journey and it's sequel Dreamfall. The main character April Ryan
 * In Scaler, Scaler gets trapped in a world filled with Lizard Folk, when escaping from a torture session. The rest of game is then spent with Scaler trying to get his claws on a 'Portal Beacon', that can get him and Leon home.
 * Some of the supplemental material for Touhou states that people quite frequently fall into Gensokyo from our world. Apparently the Great Hakurei Border is not absolutely impermeable.
 * In Date Warp, Janet and Bradley are trapped in an alternate universe where The American Revolution never happened, and the country is called Atlanta.
 * Heart no Kuni no Alice.
 * You help two people with this problem in The Trail of Anguish. But it eventually turns out that they may not be the only ones trapped somewhere unknown...
 * Astyanax (NES version)
 * Yami to Boushi to Hon no Tabibito (although in this case it's more like "trapped in several worlds").

Web Comics

 * Invoked in Erfworld, with the summoning of the protagonist, Parson Gotti.
 * If you count the "Torg Potter" stories as examples, this happens over a dozen times in Sluggy Freelance.
 * Fur Will Fly: The protagonist is trapped in another world populated by furries.
 * The main character of Astray³, Emily, transported to another world with almost no explanation as to how. She's not the only one to be magically whisked away like this, either.
 * Kagerou starts out with this trope, and then does really nasty things to it. It's a long story and involved multiple personality disorder, among other things.
 * Lucco in Fite!.
 * The whole plot of Miamaska, as Amity and Guere are stuck there.
 * Homestuck: Anybody who plays SBURB will be transported into the Incipisphere. However, the series is more of a Deconstruction of the trope, as the home planet and eventually the universe of the players is destroyed once they leave.
 * The plight of the titular characters in Bob and George, but eventually one character even points out that they are not from any megaman dimension, but nobody seems to care anymore.
 * Fiona is summoned to an Alternate Universe Earth by Jim and Van in Supernormal Step.
 * In Dubious Company, after Izor's plan goes haywire, the AntiHeroes and AntiVillains are thrown into another dimension and struggle to find a way back.
 * Parodied and played with on the Thai webcomic Isekai Transporter, which is about an association whose mission is "transport" people from our world to other ones via reckless truck manslaguther. The truck drivers are normal(ish) people from our world, but the ones doing the administrative work and who created the transporting technology are people who escaped the destruction of their homeworld, and now are collecting the resources to rebuild it back by "selling" heroes to other worlds that may need them.
 * Nerf NOW!! parodied the truck version: "Isekai'd" (see the next page).

Web Original

 * While their trip to Creturia was intentional, the Dimensional Guardians from the web fiction serial Dimension Heroes find themselves trapped in the world until they can find the objects they need to both save the world and return home.
 * The serial web novel Elcenia starts out with protagonist Rhysel being summoned to the titular Magical Land. Unusual in that Rhysel is from a different Magical Land herself.
 * This happens in the gender bender The Finite Life of a Dating Sim Heroine to the main character Michio, which takes place in the titular dating sim.
 * This setting is currently the most popular for multifandom Journal Roleplay Games. The community has even coined a phrase for games based around this setting--"spooky jamjar". Which has now come full circle- meet Roleplayedingly. A roleplay where the characters are sent to a new world every week- and every world is an existing LiveJournal roleplay.
 * The heroes of The Dragon Wars Saga are examples, although it's insinuated they could leave if they knew how and really wanted to do so.
 * In Trinton Chronicles very first story (Fantasia) all of the characters end up in a portion of the Fairy Realm or something similar.
 * According to Robert Brockway of Cracked.com, the need for a "straight man" in a Magical Land story is one of the 4 Realizations That Will Ruin Science Fiction for You.

Western Animation

 * Samurai Jack takes this to extremes, by placing a Samurai from feudal Japan in a far-future sci-fi world populated by countless alien races.
 * Dungeons and Dragons: One weird rollercoaster ride later, and the kids are in world resembling a D&D campaign setting.
 * Captain N involved the main character Kevin Keene being sucked into "Videoland", a world where Nintendo games were real (and often very misrepresented in comparison to their actual video game counterparts). Strangely Kevin seems to have no interest in going back to the real world and very rarely, if ever, expresses a desire to go home. What must his mother think...
 * In King Arthur and the Knights of Justice, Merlin needs replacements for King Arthur and the Knights of the Round Table, who have been captured by the series' Big Bad. His odd solution is to bring a contemporary American high school football team (whose quarterback happens to be named Arthur King) to Dark Age Europe to become Camelot's new defenders.
 * Kidd Video was a lot like Dungeons and Dragons but the protagonists were far more accepting of it; the Flip Side was just too cool not to enjoy.
 * Super Mario Bros Super Show, where Mario and Luigi are from Brooklyn, but were transported to the Mushroom Kingdom through a warp pipe.
 * In The Owl House, the first season averts this, as Luz is able to return to Earth any time she wants. However, this changes in the Season Finale, where she purposely destroys the portal to prevent Emperor Belos from using it, leaving her trapped in the Boiling Isles for the time being.
 * The plot of Amphibia kicks off when Anne accepts a dare from her BFFs Sasha and Marcy (or so she believes) to steal a music box; it's magical, and transports Anne to another dimension. Later episodes reveal that Sasha and Marcy didn't escape this effect and are in the same boat, having ended up in different places in the dimension. Sasha is (at first) even worse off, being a prisoner of the Big Bad but in Marcy's case, she loves being in Amphibia, having adapted Like a Fish Takes to Water.
 * Season Two has a Perspective Flip, with Anne managing to return home (leaving Sasha and Marcie behind, their fates again ambiguous for a while) with the Planter family coming with her, making it different fish trapped in very different waters.