Translator Buddy

One character has a peculiar way of speaking that may be hard for the viewer to understand. Maybe he speaks a different language, is The Unintelligible, is just so smart he can only speak in Techno Babble or suffers from a bad case of Sesquipedalian Loquaciousness. Thankfully, that character has a friend who will interpret what he's saying to the audience (and other characters). A common way to show that these two characters are close friend as only the "interpreter" understands his friend so well. This friend is the Translator Buddy.

One can reasonably expect the person being interpreted to respond to the interpretation with, "that's what I said."

Related to Why Didn't You Just Say So?. This is one of the responsibilities of a Cloudcuckoolander's Minder.

Anime

 * In the Pokémon anime, Meowth of Team Rocket translates for all the other Pokémon, especially in episodes or shorts where the trainers aren't around for the day or where Ash and friends are forced to cooperate with the Team Rocket trio. Most of the time, though, he translates for the Rocket trio's other Pokémon.
 * Kaname can understand whatever Sosuke is saying in his Bonta-Kun suit in Full Metal Panic!, despite the voice box glitch that makes everything comes out as "Fumoffu!"

Comics

 * Ben Grimm/the Thing is this to Reed Richards/ Mr. Fantastic in the Fantastic Four.

Film

 * In Dogma, The Metatron is this to God, who is The Voiceless. Well, he has his own voice present but it causes all humans' head and hearts to explode. Thus the Metatron is the voice of god.
 * Ditto for Jay to Silent Bob in the The View Askewniverse. Jay usually just speaks for both of them, but often he will "translate" Bob's more subtle hand gestures. It's worth noting that Silent Bob can speak... He just doesn't want to.
 * C3PO does it for R2-D2, who is The Unintelligible in Star Wars.
 * Worth noting that Han is not this to Chewbacca: He tends to talk to him by holding normal conversations, and generally everyone acts as if they understood Chewie, there's never some translating going on - mostly because everyone seems to understand Chewie fine.
 * This continues into the Expanded Universe where Chewie and other Wookies rarely (if ever) have spoken dialogue and are described as merely grunting or barking their half of the conversation and you're only able to figure out what they're saying by paying attention to how others respond.
 * The two alien thugs in the Cantina in Star Wars: A New Hope (i.e. "he says he doesn't like you!").
 * Obi-Wan cuts off poor Ponda's arm when things go south, even though all he wanted was to befriend Luke.
 * In several novels, Luke claims he has spent so much time with R2-D2 that he can understand most of his beeps.
 * Police Constable Bob Walker of the Sandford Police Service in Hot Fuzz speaks with such a thick rural accent that Nicolas Angel needs other villagers to translate him - a task usually handled by Danny. However, isolated country folk are unintelligible to everyone but Bob, forcing a translation chain. Interestingly, as Angel gets more familiar with the town, Bob's dialogue becomes more intelligible.
 * There's a member of Robin Hood's band in Time Bandits who speaks only in growled gibberish. Whenever he says something, Robin turns to the guy's buddy for a translation.
 * In The Marx Brothers, Chico translated for Harpo.
 * The native-American gophers in shorts between Underdog cartoons—one talks like Tonto, but translates for the other who speaks Indian gibberish.
 * Toyed with in Four Weddings and a Funeral, with Charles and his deafmute brother David. The time he has to translate what David says, it's when  Predictably, Hilarity Ensues.
 * Pseudolous, Butt Monkey and Love Interest of the Hot Amazon Gymnasia in A Funny Thing Happened on the Way to the Forum. After meeting for the first time his love intest Gymnasia the Silent, a towering blonde amazon incapable of speech and expressing herself in oddly mismatched pantomimes, he reveals that her gestures are actually an highly organized form of sign language, and he's the only character of screen able to grasp it. Everyone else thought Gymnasia as incapable of expressing at all.
 * Used in Love Potion no. 9. When the female lead, Diane, gets a sample of the Love Potion no. 8, she receives the power of a Compelling Voice, of a sexual nature and working only with the opposite sex. Upon entrancing a rich mook, to avoid the potential hassles of being chased, harassed or desired by every single man at her speaking distance, she cleverly puts the mook under the assumption she just enjoys "play the mute game", that is using a simplified form of sign language while in public, and letting him graciously act as her mouthpiece.
 * Mr. Cotton's parrot in Pirates of the Caribbean is something like this, even though Mr. Cotton himself doesn't speak at all (because his tongue has been cut out).

Literature
""It's a self-sustaining barrier produced by a recirculation of the initial power input," Telemain explained. "Because of the rotation effect, most physical substances cannot pass through the shield in either direction. Unlike the majority of spells, this one needs no exterior energy source, so the usual procedure for dismantling such sorceries would be completely ineffective." "What does that mean?" Cimorene demanded. "The spell keeps itself up, we can't get in or out, and we don't have any way of getting rid of it," Mendanbar translated."
 * In The Enchanted Forest Chronicles, there's a magician named Telemain who speaks almost entirely in Magi Babble, so Mendanbar, the King of the Enchanted Forest, often winds up having to "translate".

""And now he's offering you a bribe to snuff her," Dworkin said with a chuckle. "That is highly inelegant," Antoninus remarked. "But mostly accurate," Empodicles added."
 * In The Turbulent Term of Tyke Tiler by Gene Kemp, twelve-year-olds Tyke and Danny are best friends. Danny has a speech impediment which makes most of his words begin with a D-sound and gets worse when he's upset. Tyke frequently has to translate his speech so others can understand it.
 * Although they weren't friends, the dwarves acted as this during Year of the Griffin. Headmaster Corkoran was entertaining a delegation of Roman senators and visiting dwarves at the same time, and the Senators' speech was so eloquent and convoluted that Corkoran couldn't follow a word of it until the dwarves translated.

""The scheme I would suggest cannot fail of success, but it has what may seem to you a drawback, sir, in that it requires a certain financial outlay."
 * A running gag in Jeeves and Wooster is that Bertie has to translate whatever Jeeves is saying for the benefit of one of his "pals", most of whom are Upper Class Twits.

"He means," I translated to Corky, "that he has got a pippin of an idea, but it's going to cost a bit.""

Live Action TV
"Cop: You really think this was only one guy? Reid: The level of overkill indicates an Unsub in a psychotic break. Multiple Unsubs in violent psychotic breaks operating in the exact same location is exceedingly unlikely. Morgan: Yeah. It's probably one guy."
 * Mighty Morphin Power Rangers: Trini, is this to Billy. After Trini left the show, Billy lost the need for this, with the writers toning done his Sesquipedalian Loquaciousness along with his general nerdness.
 * In the Star Trek: The Next Generation episode Loud As A Whisper, Riva, a famous negotiator, is born deaf and mute (as are all members of his race's royal family). He has what he calls a chorus, three telepaths who speak for him, each one representing an aspect of his personality: Scholar/Artist, Passion/Warrior, and Harmony/Wisdom. When his chorus is killed, he is forced to speak by sign language. Data then takes on the role, due to his ability to learn and master 5 sign languages in a few seconds.
 * Also in Star Trek: The Next Generation: Geordi is sometimes the Techno Babble translator for Data, less often it's the other way around. Worth nothing with the Geordi/Data interaction in Star Trek: The Next Generation is that Geordi translates the Technobabble that Data gives to the rest of the crew and also explains the meaning behind various human behaviors and idioms to Data, which might as well be a foreign language to Data due to him being an android. Geordi essentially does double-duty in this role.
 * In The Big Bang Theory, Leonard spends much of his time translating Sheldon's sayings (and explaining his habits) to Penny and other strangers.
 * In The Tenth Kingdom, Tony is the only one who can understand what Wendell (who was turned into a dog) is saying.
 * In Criminal Minds, Morgan sometimes acts as this to Reid when he slips into Sesquipedalian Loquaciousness:


 * Daphne (who signs, reads lips, and speaks) somewhat operates as this literally for Emmett (who signs, apparently does read lips, but doesn't speak) on Switched at Birth.
 * The comedy/magic duo Rebo & Zooty in Babylon 5, played by the Real Life comedians/magicians Penn & Teller. Zotty doesn't speak but wears a machine that they claim translates his thoughts. Rebo usually interprets for him.

Toys

 * Matoro from BIONICLE acts as one for Turaga Nuju, who only speaks in the language of birds.

Video Games

 * In Quest for Glory II, Poet Omar only speaks in poetry verses. He has an assistant that will "translate" for him when you talk to him, explaining what he means.
 * Misha in Katawa Shoujo can and will translate everything to and from sign language when her best friend, the deaf-mute Shizune is around. And sometimes when she isn't around.
 * Hisao sometimes serves as this in Shizune's route, in which he learns sign language.
 * Played straight in Mother3 with Fassad and his interpreter shortly after

Web Original

 * Eleonora plays this role for her brother, Menelaos, in Greek Ninja, as his speech consists mostly of mistranslated Greek.

Western Animation
"Tom: One can only surmise that this establishment manufactures prestidigitation equipment. Suzie: Alan? Alan: This is where they make magic tricks."
 * In the new Strawberry Shortcake stories, Blueberry Muffin does this for Longface Caterpillar.
 * Scarlett to Snake Eyes who is The Voiceless in G.I. Joe: Renegades.
 * Raf is the one who interprets Bumblebee for the other kids in Transformers Prime. How he intuitively understands binary clicks just as well as he does English is not explained.
 * Alan is this for his brother Tom on The Amazing Chan and The Chan Clan:


 * Zilly, for Klunk, in Dastardly and Muttley in Their Flying Machines.

Real Life

 * Stephen Hawking, English theoretical physicist and cosmologist, has a motor neurone disease. It has progressed to the point where he had to have a tracheotomy and now can't speak at all. However, in the past he was able to speak but his speech became slurred so that he could be understood only by people who knew him well. He would teach classes and give lectures with someone translating for him.
 * Sharon Osbourne frequently turns the shaking, Brummie string of near-incoherent non sequiturs that pass for speech in Ozzy's world and translates for the world at large, especially in interviews.
 * Baby talk. Sometimes nobody understands what a toddler says, except a parent or an older sibling.
 * Special needs children can sometimes require their caretakers to translate their speech or signs.