Trapped In Another World - Television Tropes & Idioms

A standard plot/Myth Arc for fantasy/SF anime: The Ordinary High School Student, frequently his friends, and sometimes his enemies are all transported 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).

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 You Cant Go Home Again.

Examples:

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 of course the sequel Ashes To Ashes.
Doctor Who: Rose is trapped in a parallel world, but returns with knowledge of "the Darkness" threatening to destroy the multiverse (as her universe is ahead of ours). She is then forced to remain in her parallel world to take care of the clone-Doctor, despite wanting to stay with the real one. Former boyfriend Mickey, however, decides to leave the parallel world for the real one.
A staple premise of series by Sid and Marty Krofft such as The Lost Saucer, Liddsville, Dr. Shrinker, Land Of The Lost and H.R. Puffnstuff.
Farscape, where Crighton 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.
The Time Tunnel - two guys trapped in the past (or occasionally the future).
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.

Anime

Abenobashi Mahou Shoutengai: After the first episode, the heroes fall from world to world, each one based on one of the main characters' geekish hobbies.
The first and fourth seasons of Digimon.
El Hazard The Magnificent World
Full Metal Alchemist: Used in The Movie; in a subversion, 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.
Magic Knight Rayearth
Parallel Trouble Adventure Dual
The Twelve Kingdoms: Youko and her friends 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.
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.
- Actually more like a second Earth than a moon, and probably impossible in terms of RL orbital dynamics...
Aura Battler Dunbine, but then it twists it by having all the people from the other world get sent to Earth.
Monster Rancher
Kyou Kara Maou: Though he 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.
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 six episode trip through the ninth ring of Hell.
Kagome from Inu Yasha in the first few episodes. Afterward she's able to go between the other world and her own at will.
Slight subversion: Yukinari from Girls Bravo gets trapped on the planet Seirun in the first episode, but is returned to Earth in the same episode.
Has nobody mentioned Spirited Away yet?
In Death Note, Ryuk is stuck in the human world until the Death Note he dropped in the human world is destroyed or the owner dies. However, this was intentional on his part, since his Shinigami Realm was so boring.
The Mahou Sensei Negima manga has Negi and a group of his student get stuck in the Magic World after Fate destroys the gateway between worlds.

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.

Literature

The Fionavar Tapestry by Guy Gavriel Kay. 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 nearish 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 two going back to our world and marrying each other, one choosing to stay in Fionavar, one dead in a heroic sacrifice, and one sailing off to eternity with Lancelot and King Arthur as she is, in fact, Guinevere. The books are somewhat eclectic.
Alice In Wonderland: One of the earliest and most famous versions of this trope and a template for many later stories.
The Chronicles of Narnia: 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.
The Wonderful Wizard Of Oz. Most of the first six-odd "Oz" books by L. Frank Baum 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 being a much more utopian place to live, occasional monsters and baddies notwithstanding).
- More important than the Witches dying was Ozma taking the throne.
The Chronicles Of Thomas Covenant are based on this.
- Stephen R. Donaldson is fond of this one - it's also the premise of the Mordant's Need novels, where a woman from the 'real world' is trapped in a fantasy realm where any reflective surface can access another universe.
Un Lun Dun by China Mieville
Neverwhere by Neil Gaiman
The "John Carter Of Mars" series and the "Pellucidar" series, by Edgar Rice Burroughs.
Mike Grell's DCU comic The Warlord, a deliberate homage to Pellucidar (in setting) and Barsoom (in tone).
"The Merchant Princes" series, by Charles Stross
In The Dark Tower, Roland draws his ka-tet from New York City at various points in time to his own world.
In Alan Dean Foster's Spellsinger series, the main character is mistakenly summoned as a powerful wizard.
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.

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
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 no episodes involve him trying to find a way back 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.
Super Mario Bros Super Show, where Mario and Luigi are from Brooklyn, but were transported to the Mushroom Kingdom through a warp pipe.

Video Games

Dragon Quest 3. Combines Alternate Dimension with Time Travel, as Your hero turns out to be the legendary Roto, heroic ancestor of the Dragon Quest 1 and 2 Heroes. This also means that 90% of the game is the prologue.
Final Fantasy Tactics Advance. And its sequel.
Final Fantasy X. However, it's revealed that Tidus's world wasn't even real to start with.
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 Pokemon Mystery Dungeon games combine this with Involuntary Shapeshifting, turning your human character into a Pokemon and stranding them in a world full of other talking Pokemon.