Aliens of London

"Rose: If you're an alien, how come you sound like you're from the North?

The Doctor: Lots of planets have a North!"

- Doctor Who, "Rose"

When aliens helpfully speak English (or any other Earth language), an issue comes up - what sort of accent do they have?

As is the case for any language, "unaccented" English doesn't exist (although if argued, it could be in Oxfordshire, the origin of the modern English vernacular and the RP dialect) When you don't notice someone's accent, that's because they're speaking with a very familiar accent - either your own, or a "broadcast standard" like American Broadcast English in the US and Received Pronunciation in the UK. So what sort of accent would an alien, a being with a wholly unearthly language background, have?

In movies and television, the most common answers are the most pragmatic: The accents of the actors playing the aliens, or if any of those accents would stand out too much, The accents of the audience.

Those are the easiest solutions, and viewers often don't think about it as long as the accents are unremarkable to them. Have an actor speak with a strong and identifiable accent, though, and the same people who wouldn't think twice about an alien talking like a Londoner or a Midwesterner start wondering why the extraterrestrial sounds like someone from New Orleans, Sydney, or Manchester. You also see this reaction when shows reach other countries and new viewers are puzzled (or amused) at the entire rest of the universe speaking like Brits or Yanks.

Naturally, ignoring the issue of accents isn't the only option. After all, if the aliens have learned how to speak English, they could have their own accent, shaped by their alien language (and possibly their alien mouths). On the other hand, if the aliens work very hard in their language classes, then they might learn to speak with a particular human accent, perhaps that of their teachers or one of the broadcast standard accents. Going the easier route, if translation technology lets humans understand aliens speaking their own languages, then what accents the translator uses are entirely arbitrary; this could be the accent of the manufacturer, one of the broadcast-standard accents, or just an option changed with a turn of a dial.

Now, representing some of these choices is trickier in certain media than others: writing "he spoke with a Rigellian drawl" is vastly easier than making up an accent and coaching actors to use it reliably. That doesn't stop some television or movie productions, though. After all, it's always possible to cheat by boldly mangling an accent or exploiting a foreign actor's own real accent when most of the the audience is unfamiliar with it. Still, getting this week's guest star to properly "talk like an alien" may be easier said than done...

Again, this isn't simply an English-language trope - every language has accents, and the same issues come up in Science Fiction works in those languages.

Anime and Manga

 * In Tenchi Muyo, aliens even have Japanese names... though it's hinted that Juraians actually colonized that little corner of Earth (and explicitly stated as such in the (Japanese-only supplementary material), so... not quite...

Film

 * Contrary to established Star Wars myth, not all Imperial officers in the first three films have an English accent. The storm troopers all speak in American accents, as well.
 * The Clone Troopers in the prequels all have New Zealand accents, because the man they were cloned from had one. This apparently makes sense to George Lucas.
 * He (Jango, not George) did have a large hand in raising the clones, so that may be part of it. Note that the more rebellious clone commandos tend to have different accents, insinuating that they do it as a form of protest.
 * In some Expanded Universe material, there's a reference to a "Coruscanti accent" that is implied to be what we hear as British in the films. Hence characters like Obi-Wan Kenobi or Grand Moff Tarkin speaking with "Coruscanti" accents, while characters from more distant parts of the galaxy use American accents.
 * Considering Palpatine is from a backwater planet where people have American accents, we can only assume he worked to lose his "Naboo accent" and adopt a "Coruscanti" one so as to fit in better with the galactic politicians.
 * Possibly confirmed by Leia's faux British accent when speaking to Tarkin. She was using her Senatorial voice. The rest of the time, she reverts to her normal mode of speech.
 * In the Highlander films Christopher Lambert had a voice coach help him speak in an unidentifiable mix of European accents. The goal was to portray a character whose immortality had caused him to pick up accents from many different places.
 * Interesting in that a person travelling western Europe from the 1500's-1800's would likely speak French a good amount of the time.
 * In "Alien from L.A." the underground Atlanteans are actually aliens who are also apparently Australians. One character even tells Kathy Ireland "You know, in Australia, my voice is as annoying as yours."

Live-Action TV

 * Avertion: Everyone in "Frank Herbert's Dune", the recent Sci-Fi Channel miniseries, spoke with a Czech or other Eastern-European accent and the fictional language spoken in the book is an "Inglo-Slavic hybrid" with buttloads of Arabic and Farsi loan-words.
 * Actually, this only really applied to the secondary characters, as the series was made in Prague. The main characters actually had a wide range of accents. Paul, Duncan, Lady Jessica, Princess Irulan, the Baron Harkonnen, and Guerney Halleck were British, Duke Leto and Feyd were American, the Emperor was Italian, and Stilgar was German.
 * Doctor Who is generally the most recognizable example of this trope to Americans, since it depicts a universe with a wide range of accents, all of them British. This is explained in show with the idea that the Doctor's TARDIS translates all alien languages for its passengers.
 * The original series, which ignored the whole thing for over a decade, actually used someone noticing the language issue as an indication she'd been brainwashed. It's also never mentioned why the translation never seems to go away during times when The Doctor & TARDIS get separated.
 * Lampshaded in Series 5, Episode 10. Tony Curran, playing Vincent van Gogh, shares a Scottish accent with Karen Gillan, playing companion Amy Pond, so he got a line of dialogue indicating that Vincent could actually perceive this - only he was hearing her as having a Dutch accent, like himself.
 * Star Trek the Next Generation: Captain Jean-Luc Picard is the quintessential Frenchman. With an English accent. And when he goes home to France, everyone else in France has an English accent too. But perhaps times have changed. In one episode, Data references French as an "obscure language".
 * There is the language "Federation Standard" which has never been fully explained but is presumably a language to encumber every member of the Federation, regardless of series. It's probably (but not necessarily) based on English. One can assume other regional languages have become merely points of culture to people like Picard.
 * A more intriguing possibility is that due to the widespread use of universal translators, Picard is actually always speaking in French, we only hear it as English due to the translation convention. It was shown in one Deep Space Nine episode that the universal translator works in real time "through the air", so to speak (it took five minutes of episode time for it to start working on the new species of the week, up to which point they could only be heard in their native tongue).
 * For the first few seasons of Star Trek the Next Generation, Marina Sirtis affected a fake "alien" accent based on an Israeli woman she knew. Unfortunately, when her mother (played by Majel Barrett-Rodenberry) showed up, she used her natural accent. The writers rationalized that Troi's accent came from her human-but-well-traveled father. But when he showed up, accentless, for a flashback, Marina finally gave up.
 * This trope becomes more noticeable when it's subverted. For instance, Star Trek VI the Undiscovered Country has David Warner playing probably the only Klingon ever to have a British accent rather than an American accent.
 * Not to mention the fact that Christopher Plummer spent the whole movie quoting Shakespeare with his own personal accent, and nobody's really sure what the hell nationality that's supposed to represent.
 * The original Sarek was American Mark Lenard. In the 2009 film, he is played by English actor Ben Cross. As a result, Sarek inexplicably becomes English in the Abrams Verse.
 * Perhaps it's a side effect of Nero's meddling. A strange rearrangement of Sarek's vocal cords.
 * Most of the characters in the 2000s Battlestar Galactica speak with American accents, but there are a handful of characters who speak with other recognizable accents -- British, New Zealand, and Irish in particular. Why they should speak this way is never explained, as it's otherwise implied that human civilization is linguistically homogeneous. In one episode, Baltar claims his "British" accent to be a result of him, an Aerelon, attempting to affect a Caprican accent -- when he uses his "natural" tongue, it's a heavy Yorkshire accent. See British Accents.
 * They may not be exactly "linguistically homogeneous" either. Writings in French and Chinese have been spotted in the background, and French loan words such as elan and esprit de corps are used. The surname Inviere is said to be "Old Gemenese" for "resurrection".
 * The keyword being "old" - the Twelve Colonies had a bunch of different languages in the past, but everybody seems to speak "English" now.
 * Relating to the above, the spinoff prequel Caprica showcases the Tauron language, based on (or perhaps more likely represented by Ancient Greek. Since it takes place fifty years before Battlestar Galactica, it's not clear whether the other languages all die out later or if they are simply never seen in BSG because everyone speaks Caprican (which is presumably what is being represented by English). It's also useful to note that Gemenon appears to be a sort of more-religious "sister planet" of Caprica, which might be why their language might have died out earlier.
 * Of course, Japan has all aliens, magical beings, etc. speak Japanese as they speak English in English-speaking countries, but one episode of Mahou Sentai Magiranger challenged Willing Suspension of Disbelief when the Heavenly Arch Saint Magiel, the building-sized highest-ranking member of a group of magical beings from the Fluffy Cloud Heaven-like dimension of Magitopia, insisted on not being addressed with a certain honorific by the Big Bad (building-sized leader of the Scary Pit Hell-like dimension of Infershia.) Usually, Aliens of London draw the line at speaking the same language and don't go as far as to be particular about being treated according to specific social niceties of the culture they've never experienced. The American equivalent wouldn't be Aliens Speaking English, it'd be Aliens Insisting On Being Addressed As 'Ms.' or Aliens Being Offended By Being Called 'Gringos' or something like that. Finding a slightly less distinctly Japanese way of having the two characters disapprove of each other would have helped sell the premise a bit better.
 * While Power Rangers doesn't quite have an example that bad, it too repeatedly runs into this trope as a number of Monsters Of The Week have accents for no reason. Mora/Morgana of Power Rangers SPD is the most obvious, as she was a regular character. The fact that the show has repeated problems with accents since production was moved to New Zealand only complicates things.
 * The language spoken in Red Dwarf is officially called "Earth", but sounds an awful lot like British English.
 * Even funnier when you realize that most major signs in the ship are posted both in English and Esperanto, implying a bilingual culture (or a multilingual culture with two lingua franca), yet we almost never hear anyone use Esperanto at all (part of why it was later quietly retconned out of the series). Or anything other than English.
 * We only meet a small number of characters who come from the time shown at the start of the series, and it's made clear that Rimmer, at least, is hopeless at learning Esperanto, while Lister is quite good at it. Do all Canadians speak both English and French fluently?
 * It's actually a blend of British and American English. Englishman Lister uses several American terms in "Legion" (for example, he says sneakers rather than trainers) whereas American Capt. Hollister uses several British terms (and 'vacation') in Series VIII.
 * Particularly jarring in season 9 of Smallville. Zod (From Planet Krypton) is played by Callum Blue (From London). Every other Kryptonian (And we see plenty of them during this season) speaks as an American, but Zod somehow has a very noticeable English accent.
 * Since Farscape was produced in Australia, a large percentage of the cast have some variation of an Aussie accent.
 * Claudia Black also used a distinct accent for Aeryn Sun, causing problems for other actors playing Sebaceans.
 * Lampshaded in one episode where Crichton needed to impersonate a Sebacean, he asked if the translator microbes would translate accents.
 * This trope actually worked for Farscape's premise, as John Crichton was an American astronaut lost in the Uncharted Territories (clearly the outback of the galaxy), so it would make sense that the aliens spoke in accents different than his own. And since many of alien species, unlike the people of Earth, regularly make contact with other aliens and travel to other star systems, it makes sense that their accents are more similar to one another than to a human from Earth.
 * Speaking of Claudia Black, she played Vala on Stargate SG-1 with her native Australian accent. Similar to the above Next Generation example, it was Hand Waved that she had gotten her accent from her mother when Fred Willard was cast as her father and, of course, used his American accent. So apparently there's some alien planet out there where people have Australian accents. (The show didn't last long enough after that to give Vala's mother a chance to show up.)
 * While Babylon 5 gave each of its alien ambassadors noticeable accents, the other members of their respective races didn't share them -- which implies a great deal of regional differences on those planets, similar to Earth culture. While Londo Mollari sounded like an over-the-top Russian nobleman, his aide, Vir Cotto, sounded like he was from New Jersey (or perhaps Northern Virginia, where actor Stephen Furst was from). G'Kar spoke with something resembling Received Pronunciation (and not a not too shabby one, at that, given that Andreas Katsulas was from St. Louis); most Narns had some kind of American accent. While Mira Furlan's (real!) Slavic accent brought an exotic air to Delenn, Bill Mumy's Lennier merely had a clipped, precise mode of speaking not too different from any other incarnation of The Spock.
 * Katsulas is not speaking with an RP accent in B5, he's merely speaking with a fairly precisely articulated General American accent. Further, Jurasik is on record as saying: "Because I'm the first Centauri, so I make him talk any way I want. So, I made the accent up, a kind of amalgam of a number of different accents. I used a little of my Slovak grandmother, and I mentioned Ireland – I love the rhythms of Irish. So I mixed it up and made it my own.".
 * One of the TV movies featured a Centauri woman with a thick French accent.
 * An interesting thing to note was that older alien characters had thicker accents than younger ones.
 * Which make sense considering earth had only recently became a galactic power, so younger aliens probably started learning English at a younger age than their older counterparts, which would explain their lack of accent
 * Attempted avert by the wonderfully talented William Forward who played Lord Antono Refa in seasons two and three. Forward made every attempt to emulate Jurasik's bizarre creation.

Toys

 * In several of the Transformers continuities, giant robots from another planet, some inactive for millions of years, have accents mimicking a variety of present-day Earth cultures; the majority speak American English, but Cybertron Jetfire and G1 Outback are distinctively Australian, for example.
 * In his bio, Jetfire is said to have picked up his accent while stationed on Nebulon, which means we have an entire planet of Australians now.
 * And the entire populace of the planet Gigantion have incredibly fake Scottish accents.
 * In the original series, most of the robots had a straightforward, almost accentless tone, but Ironhide, Wheeljack, Prowl, Jazz, Rumble, and others had accents ranging from soft-but-noticeable to thick-yet-somehow-suits-the-character-so-we'll-let-it-go. Yeah, Ironhide is from the Texas part of Cybertron.
 * Not to mention Tracks and his Thurston Howell III, upper Connecticut accent.
 * Also pops up in the films, when the first Autobot to die happened to be voiced by a black man. In the second film, Skids and Mudflap are two idiotic robots who seem to have based their mannerisms on hip-hop culture. Specifically; they're wiggers. There's also an Australian 'Bot.
 * Let's not forget Transformers Animated, where Blitzwing has three separate German accents, the Jet Twins have Eastern European accents, Jazz is still black (but in a fairly different way, more Beatnik than Jive Turkey, and also is the first Transformer to wear pants), and, as usual, uptight bad guys are always British.
 * Timelines throws in Shattered Glass Blaster who sounds... something approaching German, while Wings of Honor Ironfist is vaguely Australian.

Video Games

 * Inverted in Star Ocean - the aliens, from Earth and with quasi-Caucasian names, all speak English in their voice clips, while the audio for the Fellpool, the alien race all the main characters are, are quite Japanese. Text is homogeneously Japanese, of course, which can probably be blamed on Translator Microbes.

Western Animation

 * Spoofed in Futurama, where French is actually extinct (except among gargoyles, apparently). Yet several characters speak it at various points... Making it just another inconsistent joke in the series (similar to how there aren't any wheels in the year 3000... except for the thousands of wheels that they have, that is)

Comic Books

 * Justified in Transformers Generation 2 Redux. While several Transformers have accents from various Earth countries, it's because those specific Transformers were either created and "raised" entirely in those various countries, or resided in one long enough to pick up the accent.

Film

 * Star Wars has the Fetts (man and clone) who speak with a distinctly foreign accent. Except to New Zealanders, who just laughed and laughed. As did South Africans (at the young Boba Fett, who seems to grow up with a South African accent but inexplicably develop an NZ one later).
 * And Australians, mind. "These Wookies are dyd", anyone?

Literature

 * Robert Heinlein's Between Planets had intelligent "dragons" inhabiting the swamps of Venus. Unable to speak human languages, they can still learn them and use hand-operated vocoders to synthesize the sounds of speech. One dragon thus "speaks" with a pronounced Texan drawl due to having a Texan teach him English, and an important character in the book is a Venerian dragon who is a highly respected physicist (not to mention a member of the aristocracy of his species)...who learned English from someone with a pronounced Cockney accent.

Western Animation

 * In Justice League, Hawkgirl speaks with an interesting, difficult-to-define accent. This ended up informing the voice acting for the entire Thanagarian species.
 * On Invader Zim, Tak has a British accent while none of the other Irkens do. Lard Nar has one too, though we only have one other Vort to compare him to.

Web Comics

 * Lampshaded in Homestuck when u uses the phrase "Bob's your Uncle" and then reveals that she isn't sure she used it right. Turns out that her British accent is a deliberate affectation or "quirk", something all trolls do to an extent.
 * Tavros does this with Spanish, and Vriska to a limited extent with Italian, both of which are straighter examples.