->''"So much for the 'legendary courtesy' of the elves. Speak words we can all understand!"''
-->-- '''Gimli''', ''Film/TheFellowshipOfTheRing'', not pleased that the elves are ''not'' speaking this

In RealLife, there are more languages than there are cultures speaking them. There are dead languages, sign languages, dialects, slang, and a thousand other variations. People ten miles away from each other might not understand a word each other says.

[[CaptainObvious This makes communication difficult]]. So, many speculative fiction writers use a shortcut: having everybody speak the same language, which can be through a single native tongue for everyone, or more plausibly, a ''[[https://en.wikipedia.org/wiki/Lingua_franca lingua franca]]'' learned by everyone as their second language.

Usually called [[Literature/TheLordOfTheRings Common]] or [[Franchise/StarWars Basic]], this is a baseline language that is used by the vast majority of the setting. Oftentimes, it is the human language, since humans are almost always the most wide-spread race, and other races will have their own "Common" language that all their members speak. All dwarves will speak Dwarven, all elves Elven (or Elvish) and so on.

If it is never stated explicitly that everyone is speaking the same language, it might be a case of TranslationConvention or even TranslatorMicrobes instead. See also AliensSpeakingEnglish and AnimalTalk.

This is TruthInTelevision with English as today's de facto global language throughout the entire world. On a more local level this happens with [[UsefulNotes/SpanishLanguage Spanish]] and Portugese in Latin America; German in mainland Europe; French in Africa; Russian in Central Asia; [[UsefulNotes/ArabicLanguage Arabic]] (and, to a lesser extent, Farsi) in the Middle East; [[ChineseLanguage Mandarin Chinese]], and Hindi in East Asia, and English in South/Southeast Asia, and Oceania. [[MyFriendsAndZoidberg Oh yeah,]] and [[AltumVidetur Latin]] used to be one.


[[folder:Anime & Manga]]
* This is typically justified in ''Anime/{{Pokemon}}'' in that they're in Japanese-like regions so everyone speaks Japanese.. Except recently the regions have expanded to be based off other countries, currently America and France. In ''PokemonXAndY'' they explicitly speak French and [[spoiler:Looker even has communication problems with a Kantonese women who speaks Japanese.]] In the anime no such language barriers exist. Ash can go from Sinnoh to Unova then to Kalos and speak perfectly with others.
* ''Manga/{{Berserk}}'' averts this; though most of the cast speak Midland's language, some characters speak Kushan, which none of the Midland cast understand.
* ''Manga/RaveMaster'' has a universal language to avoid any unnecessary language learning each time the hero travels to some new location somewhere in the world. Although there are several recently dead languages, or languages that people still use despite also knowing the universal language.
* In ''Anime/InazumaEleven'' everyone speaks Japanese, no matter what country they come from. This is obviously mostly used in season 3 of the original series, as well as Go: Galaxy, when the Football Frontier International is held and everyone from every team from every country speaks Japanese, even when they're speaking among themselves. This also applies to the aliens in Go: Galaxy as well.

[[folder:Fan Fic]]
* ''The Basalt City Chronicles'' averts this; in the Empire of Smilodons, it's said that there's a language for every island and a dialect for every village. Some cultures even have more than one language, for example the Deltharians (most of whom are deaf) have a spoken language used by the few who can hear.
* ''Fanfic/WarriorsOfTheWorld'' uses New Runic to unite the continent where the story takes place. There are other languages used (Morrocian, Umbalan and Payan within the Kingdom, Zwald within the Republic of Schwarzwald) but no one speaks any of the other languages unless they've confirmed the person they're speaking to can understand those languages as well.
* In ''Fanfic/EmpathTheLuckiestSmurf'', there's Smurf language, and there's human language which most beings (humans and non-humans alike) speak, including Psyches (though they call it Psychelian). There's also the "lost languages" of the Smurfs, which correspond to other human languages, such as Schtroumpf (French), Pitufo (Spanish), Schlumpf (German), Puffo (Italian), and Smurfentaal (Dutch). Painter Smurf occasionally speaks in Schtroumpf while Zipper tends to speak in Pitufo at times.

* ''Franchise/StarWars'' uses Basic, the language of the Galactic Republic. Nearly everyone understands it, even aliens that lack the ability to speak it. Likewise, most aliens have one language that they speak constantly. Interestingly, multilinguism is quite common--Han, for example, speaks Huttese, Wookie (though he sounds really stupid when he tries), and Rodian.
** Huttese is a secondary example, as it is physically easier to speak for many non-human species than Basic.

* The TropeNamer is Creator/JRRTolkien's [[Franchise/TolkiensLegendarium Middle-earth]]: While different lingua francas exist for different times and places, the most known is the "Common Tongue/Common Speech" of ''Literature/TheLordOfTheRings'', which at that time is spoken by lots of peoples either as a mother tongue or as a second language ''lingua franca''.
** Tolkien's work may be the trope namer, but Tolkien's handling of languages was much more subtle and realistic than later fantasy works. The CommonTongue in the time of the novels is Westron, which evolved from Adûnaic, the language of one of the tribes of men of the First Age. Adûnaic became the language of Númenor, which later became the major imperial power in Middle-Earth. When Númenor collapsed, Adûnaic was inherited by its successor kingdoms, where it evolved into Westron under influence from Elvish languages. While now almost every kingdom of men has its own language, those geographically or culturally close to Gondor, the main successor kingdom of Númenor, speak Westron as a lingua franca. Kingdoms farther away or antagonistic to Gondor such as Harad or Rhûn do not speak it. Orcs speak a bastardized Westron out of necessity, as the countless tribes each have their own mutually unintelligible dialects and can't understand each other when in large groups, as members from many tribes are likely to be present. Elves also have two languages: Quenya and Sindarin. Quenya was spoken by those Elves that journeyed to Valinor, while Sindarin was the main language of those who remained in Middle Earth. When the Elves who journeyed to Valindor returned, they kept Quenya among themselves but also learned Sindarin, making it a kind of lingua franca among the Elves. Both Quenya and Sindarin have their own dialects as well, however. The only race that has only one language are the dwarves, who speak Khuzdul, and they refuse to speak it to anyone besides other dwarves. The rest of the time they learn the language of the land in which they reside (this state of affairs is reminiscent of the Jews, on whom Tolkien based the dwarves.)
* ''ClanOfTheCaveBear'': the various individual camps of Clan people have their own languages but there is a formal Clan language that everyone can "speak" (it's non-verbal); when Ayla meets Jondalar she wants to learn the human Universal language and can't understand for a while that there isn't one.
* ''Franchise/{{Dune}}'' has Galach, derived from English mixed with some Slavic languages and a smattering of other Old Earth tongues. But there are many other languages such as the Chakobsa hunting speech of which a dialect is spoken by the Fremen, and the Atreides battle language that is signed (so enemies can't overhear) instead of spoken.
* In the ''EndersGame'' universe, there is a common language based on English called Stark, short for Starways Common.
** At the same time, many cultures, who have spread out among the stars, have retained their own languages, even though they still use Stark when working with computers or sending messages. When traveling to Lusitania, settled by descendants of Brazilians, Ender tries to learn Portuguese, and the book is peppered with Portuguese words and phrases. Several Swedish words are also used constantly, specifically those dealing with the so-called "Hierarchy of Foreigness".
* ''Literature/{{Animorphs}}'' has Galard, a Yeerk language briefly mentioned a couple of times. The Yeerks designed it to be spoken by all kinds of different host bodies with unusual vocal chords.
* In the Literature/LiadenUniverse, the common language is called Trade, and that's what it's mostly used for.
* In ''Hellspark'' by Creator/JanetKagan, the common language is called [=GalLing'=] (presumably from "galactic lingua franca"); it's an artificially-constructed language, and one of its design features is that it only uses phonemes common to all human languages, so that anybody can speak it without difficulty.
* A language called "Tongue" in ''Literature/HouseOfSuns'' by Creator/AlastairReynolds is described as the closest possible equivalent to a universal galactic language, and even then a lot of civilisations don't understand it.
* This is a puzzling matter in ''TheWheelOfTime'' series, and one of the greatest flaws in what is otherwise a masterwork of worldbuilding. Everyone in the entire world speaks the same language, with minor dialectical variations, including people who have been completely isolated for ''a thousand years''. No explanation for this is ever given.
** There are many, many accents, and some places, notably Illian, even use different syntax. As for the Seanchan, remember they were invaded and taken over by people from the main continent, who may have forced their language closer to that of other places. Still, having Common is probably just for the sake of convenience, given how there are characters from just about every country in the cast.
** Also, according to WordOfGod, literacy within the setting is unusually high due to the Printing Press being one of the few technologies to survive the Breaking of the World. Cuts down on linguistic drift a bit.
* ''Literature/{{Discworld}}'' (specifically, said by Lord Vetinari, in ''Discworld/{{Jingo}}''):
-->"And Morporkian is something of a lingua franca even in the Klatchian empire. When someone from Hersheba needs to trade with someone from Istanzia, they will undoubtedly haggle in Morporkian."
* In the ''{{Foundation}}'' series everyone speaks Galactic Standard, albeit with some dialects.
* The titular nation of Creator/TamoraPierce's ''Literature/TortallUniverse'' speaks "Eastern Common," a language shared with its immediate land neighbors like Galla and Maren.
* In the Literature/CircleOfMagic universe, characters in different countries speak different languages, but everyone also seems to know how to speak Imperial.
* In the {{Robotech}} Expanded Universe, it's revealed that though there are many languages still spoken amongst the Sentinal's races, [[ProudWarriorRace Zentraedi]] has become a sort of common tongue that everyone can understand. This is justified because the [[BigBad Robotech]] [[TheEmpire Masters]] used the Zentraedi as soldiers to create their empire, and thus the language was spread.
* The ''HumanxCommonwealth'' universe has "symbospeech", an InUniverse ConLang that became a common tongue through serendipity. Shortly after humans and [[BeePeople thranx]] met one another, they spent some time working out a language that was easily pronounceable by both species, as they had wildly different vocal apparatus, and the thranx language incorporated significant body language aspects in addition to vocalizations. When additional species were encountered, symbospeech was found to be functionally pronounceable by them, too, and thus became the ''de facto'' galactic language.
* Anne Mason's Kira Warden novels have "the interplanetary language". Theoretically, most people know how to speak it; in practice, a lot of them are pretty bad at it, and it's not very good at nuance, providing lots of work for interpreters like the protagonist.
* In ''Literature/ASongOfIceAndFire'', the main language of Westeros ("translated" as English) is actually referred to as the Common Tongue. It is contrasted with the Old Tongue, spoken by the original people who lived on the continent, as well as High Valyrian (i.e. Latin) and Low Valyrian (fantasy counterpart Romance languages), spoken by other peoples.
* In the ''Literature/{{Uplift}}'' series the ridiculously organized and stagnant culture of galactic civilization has resulted in at least twelve different Galactic languages (numbered 1-12) designed to accommodate the wide variety in vocal structures, humans seem to have the easiest time with Gal 7. One of the assorted ways that [[HumansAreSpecial Earthclan]] is different from the other oxy-breathing races is that they have languages other than Galactic, mostly Anglic and Trinary, a poetic language designed for dolphins.
** Gal One is a binary language like Morse code, mostly used to program computers.
** Gal Two is basic, logical, unambiguous... and boring.
** Gal Three, Four, and Ten are hard for humans to speak but neo-dolphins have little difficulty.
** Gal Five and Nine are completely unpronounceable to Earthlings.
** Gal Six, Eight, Eleven, and Twelve are difficult for Earthlings but possible.
** Gal Eleven is intended to be used to bridge the gap between different orders of life (oxygen, hydrogen, machine...), it's only partially successful and intended to be transmitted by radio or psi.
** On Jijo in the second trilogy, colonized by six species living a low-tech lifestyle, most people speak Gal Two, Gal Seven, and Anglic interchangeably (though Urs speak Anglic with a lisp). The latter is because the humans were the only species to know a means of recording information without electronics (books), so nearly every written word on Jijo is in Anglic.
* Generally, Creator/HarryHarrison's novels set in the future will have [[UsefulNotes/EsperantoTheUniversalLanguage Esperanto]] (a failed RealLife attempt at making one language out of many) as the language of the old Empire and as lingua franca of all worlds. In the ''Literature/{{Deathworld}}'' novel ''The Ethical Engineer'', Jason finds himself on a LostColony and tries to converse with the locals. After some attempts, he quickly finds out that their language is a degraded form of {{Esperanto}} and is easily able to communicate.
* ''Literature/TunnelInTheSky'' briefly mentions the simple but global Lingua Terra being used in an argument between an American guard and his Chinese counterpart.
* The aptly named "global tongue" in ''Literature/SsaliaAndTheDragonsOfAvienot'', which is spoken in most parts of the planet with varying degrees of fluency, though not usually natively.
* Universal in the ''Literature/{{Paradox}}'' universe is spoken by most of TheAlliance's member races, as well as their own tongues, most of which were developed by the [[{{Omniglot}} linguistically talented]] Seersa. Though in some races, such as the Hinichi and Glaseah, their own languages never caught on and they just speak Universal with a few unique words.
* In ''Literature/WatershipDown'' each species of animal has its own language, and animals don't speak each other's languages. However there is "hedgerow vernacular", a very limited language which allows inter-species communication.

[[folder:Live Action TV]]
* Commonly [[ZigZaggingTrope Zig-Zagged]] in ''Series/BuffyTheVampireSlayer'' and ''Series/{{Angel}}''. Almost every demon speaks English, even ones in alternate dimensions, until it's more dramatic for one not to.
* ''Series/BabylonFive''
** Interlac, which seems to be math-based, is strictly used for cases when this is absolutely necessary (e.g. FirstContact situations where communications need to be relatively easy to decipher).
** As it happens, most of the aliens [[AliensSpeakingEnglish spoke English anyway]], as [[JustifiedTrope because most of the aliens we see are diplomats and interstellar merchants, and Earth is the new dominant power in both of these areas]] (the Minbari being semi-isolationist SpaceElves).
** Also applies to humans, who seem to have all of their ancestral languages (for example, Susan Ivanova's native language is Russian; she has an American accent from her education in American schools) but use English as a common tongue among themselves.
** And played for a plot point in one episode. A Minbari ship, meeting an alien race for the first time, communicates to them in Interlac... [[AliensSpeakingEnglish and gets a reply in Minbari]]. Recall that bit above about the Minbari being isolationist, and you will realize the same thing the crew did... [[TheReveal the aliens were lying about not meeting the Minbari before.]]
* There was also a situation in ''Series/StargateSG1'' where four ancient races used holographic displays of various periodic elements as some kind of universal language, though the intended effect was a little vague.
** Of course, the way they chose to represent the elements (as orbiting spheres) doesn't sound like something various alien races would come up with on their own. Especially since the Asgard claim that they can't think primitively.
*** Given the language itself is thousands if not millions of years old, it was most likely a time when the Asgard could "think primitively."
* ''Franchise/StarTrek: The Federation'' had Federation Standard and the Klingon and Romulan empires had the racial languages of the Klingons and Romulans.
** Although, the line between this trope and TranslatorMicrobes was frequently blurred.
* In ''Series/DoctorWho,'' this trope is subverted - the TARDIS is translating for both the Doctor and his companions. This comes across to the audience as British-accented English.
** Except for the Ninth Doctor, who had a Northern accent.
--->"Lots of planets have a north!"
** If you attempt to speak a native's language to them on purpose while being translated, it will sound like a foreign language they know of, but can't speak themselves.
** Translation also fails if the language lacks the concept for the word you are using, E.G in ''Fire of Pompeii'' when a companion tries to warn the citizens about a volcano they didn't understand as Latin didn't have a word for it during that time period - until Mt. Vesuvius erupted. This justifies the Doctor's technobabble as both things untranslated (nonsense words), and him having to work around this limitation by explaining things out or use metaphors. A good example of this in real life is "layman's terms", wherein somebody is trying to explain specialized knowledge to somebody who doesn't know specialized vocabulary or key concepts.
* [[AllThereInTheManual Some background materials]] for ''Series/{{Firefly}}'' indicate that just about every human ethnic group is represented in the 'Verse ''somewhere'', so English and/or Mandarin Chinese are this in-universe.

[[folder: Tabletop Games ]]
* ''TabletopGame/{{Space 1889}}'' Mars has Koline as a trade language.
* ''TabletopGame/DungeonsAndDragons'', being heavily based on ''Literature/TheLordOfTheRings'', uses this extensively. But tries to not give in ''completely'' as it has language-related magic. Specific settings are likely to have a "Lingua Franca" and a handful of specific languages.
** ''ForgottenRealms'' subverts this by having several "trade languages" even on Faerûn. Usually people can talk to each other, but on the larger scale there are Common "common" (Heartlands' dialect of [[{{Planescape}} Planecommon]]), Kara-Tur "common", Undercommon (mix of Dwarven, Gnomish, Low Drow, Upper Common etc), Auld Wyrmish ("common" across dragon subspecies). Other continents may have their own "common" languages, like Midani of Zakhara. While [[FantasyCounterpartCulture many specific cultures]] retain their own tongues still, though some reduced to dialects of "common". So learning all half a hundred or so present tongues (like Wemic or Gnomish speech) is unnecessary, but doesn't that ''comprehend languages'' spell seem worth learning now? (If you want to talk back, you might need the ''tongues'' spell too.)
** Some other D&D settings have a named language (usually human) that serves the in-game function of a Common tongue, such as Thyatian in Mystara (the language of the Known World region's dominant empire) or Balok in Ravenloft (language of its oldest domain, favored by merchants).
** Simplified in 4th edition, (no surprise there) for the most part there are only ten languages, with Common being the trade language. There are however 7 other languages for different regions.
*** Of particular note is the Supernal language, the language of the Gods, the very first language. When the speaker speaks in Supernal, everyone would understand what the speaker says as if in their own native tongue. In fact, all other languages are variants of the Supernal, in how the various races perceived the Supernal language. While you can learn the Supernal language, ultimately subverted because mortals lack the necessary power to fully speak in Supernal, thus losing its capability as universal language.
** One old 1E article on AD&D languages proposed that Orcish, Goblin, Kobold, Gnoll and similar tongues weren't separate racial languages, but dialects of a ''monsters''' version of this trope. This would explain why such races, never renowned as intellectuals, automatically knew each others' languages in the 1E era.
* ''{{Traveller}}''. Galanglic was the official language of the Third Imperium, though many worlds only used it for interstellar communications or traffic control. The Second Imperium spoke English and the First Vlani.
* ''TabletopGame/{{Rolemaster}}''
** In the ''Spacemaster'' setting ''Privateers'', the language Species Standard is spoken by all of the known intelligent races.
** ''Shadow World'' setting supplement ''Star Crown Empire and the Sea of Fates''. Across the Central Basin the most commonly spoken language is Trade Common, AKA Imperial Common. It is even spoken outside the Star Crown Empire.
* TabletopGame/{{Warhammer}} tends to lean on Reikspiel, the language of the Empire, in this capacity. It isn't a universal world language by any means, but the Empire is easily the biggest and most prominent of the human realms, and hence its language has a certain reach and importance as a Lingua Franca. Most elves, dwarfs and others who deal with humans tend to learn Reikspiel for communication (the elder races finding it childishly easy, but crude and ugly on the tongue), and even brutish races like Orcs and Beastmen tend to learn a few choice boasts and insults to torment human victims with. In the RPG, set largely in the Empire, all characters are presumed to know Reikspiel, but non-Imperial characters also get their own native language for free. In the first edition, however, Reikspiel was just a dialect of a true common tongue called Old Worlder (which had its own Greek-and-Latin equivalent in Classical Old Worlder).
* The "Gothic" language in TabletopGame/{{Warhammer 40000}} serves this purpose for the Imperium, acting as a way for cultures from different worlds to communicate. There is also High Gothic, which is used for official purposes and has a role similar to Latin in medieval Europe in that no-one actually uses it as a first language but scholars and those of high rank are expected to know it.
* ''Dark Dungeon'' RPG, supplement ''Samaris, Island of Adventure''. In the world of Yaddrin, the Common Tongue is spoken by most merchants and travelers.
* ''[=Mythus=]/DangerousJourneys''. The common tongue of the Aerth was Trade Phoenician.
* In the default ''TabletopGame/{{Pathfinder}}'' Inner Sea setting, Common is actually Taldan, the language originally spoken in the VestigialEmpire of Taldor, which was the last major empire to control most of the region.

[[folder:Video Games]]
* ''Franchise/MassEffect'' makes heavy use of TranslatorMicrobes in the form of computers that need to be regularly updated for new languages, as practically every species in the setting is as linguistically diverse as humans. There is, however, a "trade tongue", which Shepard refers to as "Galactic" at one point -- a simplified artificial interspecies language, essentially Space {{Esperanto}}.
* ''VideoGame/TheLongestJourney'' gave us Na'ven or Alltongue, a magical language spoken in all of Arcadia (a parallel universe). Its omnipresence is justified with the fact that you can become a fluid speaker after listening to it for just a few minutes, as April does upon her first visit to Arcadia. It's magic. Interestingly, Zoë from ''VideoGame/DreamfallTheLongestJourney'' doesn't appear to need to listen for several minutes before learning the language. Perhaps it's because [[spoiler:she's not really there and is only dreaming]].
* Common in ''VideoGame/{{Warcraft}}'' games. It is primarily the language of humans, but nearly everybody can speak either it or Low Common, which sounds like a HulkSpeak version of Common. Now, it makes sense that races allied with humans would learn their language, and the orcs could've picked up how to speak it during the war or while in internment camps, but it makes less sense when tauren in ''VideoGame/WarcraftIII'' can communicate with humans and orcs despite never meeting either one. In ''VideoGame/WorldOfWarcraft'' Common is the Alliance universe language (the Horde has Orcish) and is not understood by Horde races. However this is because of game mechanics (blood elves and undead should definitely be able to speak it, as well as many orcs and goblins) and there are still [=NPCs=] in game that can be understood by all factions.
** It's implied that the Forsaken lose the ability to speak the languages they knew in life (a tailor in the undead city in WoW says his former family were speaking a language "I no longer understand".
** However, a later RPG book states that Forsaken can still speak Common, but refuse to do so to distance themselves from their old lives. Instead they speak Gutterspeak, formerly the thieves' cant of Lordaeron.
* In ''DarkstarOne'', all alien races use a language called Terra (read: [[AliensSpeakingEnglish English]]) in order to make communication between them easy.
* ''Franchise/TheElderScrolls'' series does this, though it also features extinct languages, like the languages of the Dwemer and Falmer, and formerly extinct languages like the Dragon language, which the player can learn in ''[[VideoGame/TheElderScrollsVSkyrim Skyrim]]''.
** And ''living'' languages, such as Dunmeris (and a number of other languages, but Dunmeris is the one that got the most exposure and translations). And then there's Aldmeris, the local Latin-equivalent in that it didn't so much go extinct as gradually evolve into a set of related languages.
* ''VideoGame/FlightRising'' has Draconic as the general language most dragons use. The Coatl breed is the only breed to have its own seperate language and they struggle to speak Draconic but can learn it if necessary. The non-dragon Beastclans have their own separate language as well.
* While the [[ScaryDogmaticAliens Covenant]] of ''Franchise/{{Halo}}'' make liberal use of TranslatorMicrobes, the common tongue between their various species is the main language of the Sangheili/Elites.
* ''Franchise/DragonAge'' has the King's Tongue, which was apparently invented by the dwarves to replace a more archaic and formal language, and spread to the surface races through trade. Humans seem to have no other language, while the elves have forgotten all but the last vestiges of theirs.


* ''Webcomic/SchlockMercenary'' actually has ''five'' common languages: Galstandard West (which seems shockingly like English), East, Eight, Brown, and Peroxide. Given recent revelations that Galstandard Peroxide is only spoken by ocean-dwelling creatures, it seems as though each language is tailored to a specific voice and vocal type.
* Most units in ''{{Erfworld}}'' speak Language, but Natural Allies have their own (unnamed) languages, and only a few members of each tribe speak Language.
* Standard English in ''Webcomic/{{Pacificators}}''. Moreover, the Pacificators are actively discouraged from speaking in their native languages (hence why the platoon always nag on [[SiblingTeam Larima and Taffe]] when they speak in French). [[spoiler: The fact that Muneca has slipped into Spanish a few times is a significant CharacterDevelopment.]]
* In ''Webcomic/{{Harbourmaster}}'', Standard is the primary language for communication in the futuristic civilization the story takes place in.

[[folder:Web Original]]
* [[AliensSpeakingEnglish English]] is the common language of the ''entire universe'' in ''ChaosFighters'', as explained [[http://journal-of-murazrai.xanga.com/755247488/page-104-random-chaos-fighters-tidbit-1/ here]].
* The First Federation of ''OrionsArm'' attempted to standardize "Anglic", but once the Feds lost power Anglic evolved into a family of languages several times more diverse than the current Indo-European family.

[[folder:Western Animation]]
* All the various cultures in ''WesternAnimation/AvatarTheLastAirbender'' appear to share the same language. From pole to pole and around the world.
* ''WesternAnimation/HeManAndTheMastersOfTheUniverse1983'' and ''WesternAnimation/SheRaPrincessOfPower'': Pretty much all of the countless species and races on Eternia speak or at least understand English. Furthermore the same applies to Etheria, Trolla, Primus... pretty much any planet or dimension the characters encounter, including Earth making this also a case of AliensSpeakingEnglish.
* Applies to the original [[MyLittlePonyTVSpecials My]] [[MyLittlePonyTheMovie Little]] [[MyLittlePonyAndFriends Pony]] cartoon. Everyone in Ponyland and the surrounding territories speaks English, which was certainly helpful when Firefly enlisted Megan's aid.

[[folder:Real Life]]
* The alternative name for common language is ''lingua franca'', which translates literally into "Frankish language". The original ''lingua franca'' was a pidgin language based on Medieval northern Italian dialects, but also containing elements of Medieval Latin, Medieval French, Medieval Ibero-Romance languages (e.g. Old Spanish) and Arabic. It was used as a trade language all around the Mediterranean during the Middle Ages. Since all Romance languages stem from Latin, even today they are mutually intelligible to some extent, and in the Middle Ages they resembled each other much closer than today, it was easily understood everywhere.
* English is the most universal example of this trope In RealLife, due mostly to the very expansive English speaking British Empire and later the global dominance of the United States in the latter half of the 20th century. Although it is not the most natively spoken language, it is the most often taught as a second language, and thus the most widely spoken. This is confirmed by international treaty, which stipulates English as the official language of aerial and maritime communications, and is considered a working requirement for various scientific fields. They don't call it "The world language" for nothing.
** Previously, French held a similar position due to its widespread use among the aristocracy of Europe. Today, French is still extremely common as a second language.
** While German is still a rather universal language in mainland Europe, it is mostly useful when talking to older people who never learned English in school but learned German for historical reasons (especially World War II). Many younger people can still speak some German, but as a second language English has gotten ''much'' more popular (few young Europeans without German as their native language speak it fluently, while many young Europeans without English as their native language do speak it fluently). So when the older, German-proficient generation has died out, it seems that English will be even more universal and German will not be that useful anymore.
* Spanish is the second most widely spoken language in the world after English due to the vast Spanish Empire of the XVI century. Nowadays, it's used in Spain ([[CaptainObvious obviously]]), most of Latin America, the south of the United States (states like Texas even are officially bilingual, while states like California are de facto, if not de jure, bilingual), a couple of African countries and Philippines. Since the Spanish language is supervised by the institution known as the "Real Academia de la Lengua Española" or R.A.E., grammar rules are 99% the same in all of them. However, vocabulary and idioms vary a lot from country to country, and even from region to region. There are around 9 different accents in Spain alone. Nevertheless, when something needs to be written or translated for all Spanish speaking countries equally, there is a convention known as "Neutral Spanish", which consists in using the most plain words in the language so anyone can understand it without major confusions. Not a perfect solution, though, since there are always words or sentences that sound a little bit unnatural to people from one country or another. That without mention that it limits the quality of the writing.
* {{Esperanto}} is an attempt at this.
* [[http://en.wikipedia.org/wiki/Transpiranto Transpiranto]] is a parody of this.
* Further constructed languages attempting this: Interlingua and Ido.
* Also Loglan and its derivation Lojban (short for "logical language" in English and Lojban respectively). The former of which was mentioned in a couple of Creator/RobertAHeinlein's novels for use with AIs.
* As part of the legacy of the conquests of AlexanderTheGreat, Greek used to be pervasive throughout the old Eastern Roman Empire, to the point where even Literature/TheBible was translated into it so that it could be understood by Hellenized Israel. Hellenistic Greek is actually the Trope Co-Namer, as its most basic and used variety was known as ''Koine Dialektos'' (literally, the Common Tongue).
* Russian, conversely, enjoyed this status in the Communist bloc; learning Russian there was like learning English in Europe. It still works that way in the countries of the former Soviet Union.
** In newer generations, not exactly anymore.
** Russian, with English, also functions as a common tongue language in outer space.
* There have been attempts to "reconstruct" the original Sioux language, before the splitting into five dialects. This results in things like a sound not unlike the Japanese r instead of the /l/, /d/, and /n/ that are so famous, though no r-like sound exists in modern-day Sioux languages.
* In past centuries, French was the language of choice for international communication. Many French are still bitter about this.
* The language people know as "Chinese" is actually only Mandarin, which is spoken largely everywhere due to it being taught as part of the official curriculum. Otherwise, people in China speak a large family of languages sufficiently dissimilar that knowing one doesn't help in understanding another.
** However, their common descent (from the Old Chinese language spoken up to about the [[DynastiesFromShangToQing Warring States Period]]) means that ''learning'' them is easier once you know one of them; ask native English speaker who has taken French and then Spanish (or any other combination of Romance languages) how much easier the second language was than the first for a comparable phenomenon[[note]]Conveniently, the split has further analogues: the Min languages split off before the other ones (which evolved from Middle Chinese), much in the way that the Balkan dialects of Vulgar Latin that became Romanian and its close relatives were more separated from the Italian and Western dialects were separated from each other[[/note]].
** Chinese linguistic unity is further increased by its logographic (each symbol represents a word) system of writing; the same glyph would be pronounced differently in each language, but usually remains the same. Therefore, a written language independent of speech, known as Classical Chinese, developed, serving as a CommonTongue (or Common Pen?) for the educated not only in China, but also countries under Chinese influence (Japan, Korea, and Vietnam). However, Classical Chinese was based on Late Old Chinese and thus did not reflect several features of more modern Chinese languages, including pronunciation[[note]]Contrary to popular belief, most Chinese characters ''do'' reflect pronunciation; they are usually composed of two parts, one giving the sound of the syllable it represents, and the other indicating the meaning)[[/note]] and grammar. Classical Chinese fell out of use shortly after the [[UsefulNotes/NoMoreEmperors Xinhai Revolution]] of 1911, but the Republic of China (Taiwan) used it well into the 1970s for certain government documents.
*** That said, the bit about each character having the same meaning in different languages only bears true for single-character words. Various languages and dialects in Chinese will use different character groupings to describe the same thing, particularly for things that did not exist until recently. This is what was lost with the end of Classical Chinese: it was an exclusively written language which carried the same meanings across dialects but which would be pronounced differently based on who was reading it. When that was abolished, the ability to communicate in writing across linguistic boundaries in a "neutral" manner also disappeared.
* India is in the same boat as China: there are ''thousands'' of languages, but almost everybody there speaks Hindi or English.
** After India became independent, there was a movement to purge British influences including English. The return to traditional languages failed because it was far too useful to have a single standard language that most educated people already knew. Economic reforms in TheNineties, which opened India to the wider world economy in which English is a huge advantage, put the final kibosh on any attempts to remove English from the country (and gave rise to the OperatorFromIndia trope).
* In even earlier centuries, Latin was the preferred language for scholarly discourse. Latin is ''still'' in use by the Roman Catholic Church as its preferred language for edicts and internal documents.
** A working knowledge of Latin was still vitally important for students of zoology, biology and medicine until well into the second half of the 20th century, and has occasionally been used as a ''lingua franca'' when scientists from many different cultures lack another common language.
* The Standard Italian language was standardized by Dante Alighieri (author of ''TheDivineComedy'') as a heavily-Latinized variant of the Tuscan dialect of Florence, with a variety of other influences from other dialects (mostly Northern and Central Italian). Various other poets and writers had started writing in the vernacular, but Dante made it an acceptable literary language.
* In general, when a large empire spreads its language around and then dies (either by being conquered or by [[BalkanizeMe splitting up into squabbling fiefdoms]]...or as often happens, [[TheRomanEmpire both]]), the language usually starts to diverge into dialects, which dialects eventually become mutually unintelligible. However, that language may persist as a CommonTongue for the educated.
** One of the weirdest cases of this has to be the situation of UsefulNotes/{{Arabic|Language}}. Nationalism and the printing press--factors that tend to stabilize languages--arrived at a time when the dialects of Arabic formed a continuum[[note]]e.g. an Egyptian speaking entirely in dialect can relatively easily understand a Palestinian doing the same, and a Palestinian a Syrian and a Syrian an Iraqi and an Iraqi a Kuwaiti and a Kuwaiti a Bahraini, but the Egyptian and Bahraini can barely understand each other if at all[[/note]] with only one significant break (between Western "Maghribi" and Eastern "Mashriqi" dialects,[[note]]Or alternately between ''Darija'' and ''`Ammiyya'', after the native word for the colloquial speech: ''Darija'' ("low, base") is used in Western, ''`Ammiyya'' ("popular, common") in Eastern[[/note]] right about where the border between Egypt and Libya is today), and even that wasn't a complete one. Additionally, everyone in the region used various forms of Classical Arabic (the language of Literature/TheQuran) for educated writing. As a result, Arab scholars developed Modern Standard Arabic, a streamlined form of Classical Arabic that also tends to get flavored with the dialect of the user[[note]]For example, Egyptians will pronounce as a hard "g" what everyone else pronounces as a soft one, a Tunisian and a Syrian will call months by different names, and ''everybody'' prefers to use subject-verb-object sentences ("Sam eats oranges") rather than the verb-subject object ("Eats Sam oranges") preferred by Classical Arabic, to say nothing of how lists are now almost universally "X, Y, and Z" rather than "X and Y and Z")[[/note]], but which is universally understood by anyone who has been to school in an Arab country. However, people still speak their native dialects in all but the most formal circumstances; even in semi-formal situations, people will speak in their native dialect but use a lot of Modern Standard vocabulary. This last bit is the cause of a major fight among the Arab literati--many feel that this "educated colloquial" should form the basis of a new standard, abandoning the Classical entirely. Those who accept this view themselves bicker about whether one "educated colloquial" should be adopted as a single standard for all Arab countries (creating a new CommonTongue) or whether each country or group of countries should adopt their own standards (abandoning the idea of a single Arabic language altogether); those who agree that there should be a single new standard are wont to bicker over whether it should be based on one dialect of the "educated colloquial" (usually Egyptian, because everyone knows it anyways[[note]]from watching altogether too many Egyptian movies and altogether too much Egyptian TV[[/note]]) or some kind of amalgamation (in which case, how would you do that, etc., etc., etc...).
*** Arabic itself could count as a common tongue, since it is widely used in Muslim countries for studying the Quran, though only a fifth of all Muslims use it as everyday speech.
* The Japanese dialects aren't so different that people would have too much trouble communicating with each other (aside from a few cases of SeparatedByACommonLanguage and when Okinawan get involved), but they still have ''hyojungo'', or "standard language", that is roughly based on the Kantou dialect.
* American Sign Language is this for the deaf world, mainly because for the longest time, the United States was the only country with colleges for the deaf, and even today, it still remains the only country with the ''only'' university for the deaf (Gallaudet University). Many American deaf students would grow up, and go to establish schools for the deaf in other countries; therefore many of the countries' own sign languages are either derived from or affected by American Sign Language - or they simply use American Sign Language. (Fun fact: American Sign Language originally derived from French Sign Language, with strong influence from the old sign language of Martha's Vineyard; British Sign Language is totally different.)
** As a strong example of this, American Sign Language is much more popular and spoken much more often than Japanese Sign Language in Japan... ''to the point that some of the younger Japanese deaf students don't know Japanese Sign Language.''
* Software often can be described into a common tongue, mostly by using pseudo code. This breaks it down a routine into commonly used keywords that can be "translated" into other languages easily. Another method is describing it with diagrams and models, for which the Universal Modelling Language (UML) was designed to do.
** In a more literal sense of this trope, almost all programming languages are in English.