Signed Language

Signed Languages are languages which primarily function non-verbally through visual signals, generally invented for the use of the deaf to communicate. As the name indicates, the primary means of communication is generally signs made with the hands in front of the body. However, most sign languages include facial expressions and some, such as Japanese Sign Language, include mouthing as part of their mechanics. It is important to recognize that while almost every community with a spoken language also has a signed language, the signed language used is related more to the geographical region than to the spoken language. For example, English is the primary language of the United States, Canada, UK, Australia and New Zealand, but the US and Canada use ASL, the UK uses BSL, and Australia and New Zealand use AUSLAN and NZSL respectively - all related languages but with distinct signs and grammar.

One important aspect of Signed Languages is that they are, as a rule, fully formed languages with their own grammar and words. They are not pantomime nor do they necessarily follow the grammar of the spoken language of the region. Some signs are iconic, or resemble what they speak of, much like how some spoken words are onomatopoeic, but most signs are abstractions of iconic signs or completely original. The grammar itself frequently differs greatly in part due to the spatial aspects of signs and the ability to convey information non-sequentially. For example, within ASL, it is common to establish specific people in a conversation at spatial locations and later use signs moving from location to the other rather than having to reestablish identities or use pronouns. Similarly, since both hands and the face can be used, multiple pieces of information can be encoded into a single sign. For example, a sentence like "I drove from Jane to John and I enjoyed it" can be conveyed in a single sign if Jane and John have already been previously established in the conversation.

It is worth noting that Signed Language, while non-verbal, is not necessarily quiet. Even deaf users typically make sounds while signing and it is not infrequent for a very low-pitched grunt to be used to catch someone's attention via the vibrations.

Signed Language has nothing to do with the trope of Talking with Signs which involves characters communicating via signs. It is related to Hand Signals, which range from pantomime to a reduced vocabulary, sometimes with a sparse grammar. Especially within fantasy works, it is not uncommon to have races or nations where Hand Signals have evolved into a Signed Language, typically to provide a method to communicate in secrecy.

Comics

 * The Bronze Age Teen Titans version of Jericho communicated only in sign language (his vocal cords had been cut by his father's enemies). If he spoke at all, it was because he was possessing someone. Marv Wolfman also prohibited the use of thought bubbles when writing him in the comic, leading George Perez to get creative when displaying hand gestures. This trait is carried over into his animated appearances.

Film

 * All of the undersea settlers in Dark Life know sign language, because the liquid oxygen substitute they use when diving keeps them from talking out loud.
 * In What Women Want, there's a moment when Nick Marshall believes he has got ridden of hearing women's thoughts. Until he sees two deaf women using signed language and he can hear what they're saying/thinking.
 * Deafula is about a deaf vampire. The film is completely performed in sign language, with no spoken dialog. And yes, it really exists.
 * The Crucible, a 2011 Korean film based on the true story of a sex abuse scandal at a school for the hearing-impaired, naturally has a great deal of subtitled KSL (Korean Sign Language).

Literature

 * Forgotten Realms:
 * The Drow hand code in R.A. Salvatore's novels (the ones with Drizzt Do'Urden). Drow elves are all taught a language composed entirely of hand signals. Any two Drow can communicate in this way in complete silence as long as they can see one another. And in complete darkness, because of their infravision.
 * Some surface Elves in Forgotten Realms, according to Return of the Archwizards by Troy Denning, have "finger talk". As opposed to at least part-"hieroglyphical" Drow signs, it's alphabetical language and at least to some degree useable with human hands. Specifically, it was used by scouts, in which context it makes sense to go for flexibility, rather than for speed like with "tactical" languages.
 * The Finder's Stone trilogy mentioned thieves' hand cant. Saurials can't speak aloud, so it came in handy, teaching a paladin to understand it. Wait...
 * The Clan in the Earth's Children communicate primarily by sign language and Body Language, using vocal noises only for names (based on a now-disproved theory that Neandertals had less-capable vocal cords than do Homo sapiens and could not have supported a fully-verbal language). Visual miscommunication is Played for Drama several times in Clan of the Cave Bear, with The Resenter always turning away before someone compliments him.
 * The Drasnian secret language, of the Belgariad, by David Eddings. All Drasnians involved in the intelligence community (which apparently means "all of them") are taught a language similar to the Drow version above. On more than one occasion, two such speakers converse verbally about something unimportant while having a completely separate discussion with their hands. The language is specific enough that a speaker can gesture with a recognizably outlandish "accent": when Garion first learns it, Silk notes that his initial use of it is a bit off due to learning it in a cold environment (with finger joints frozen).
 * Characters of the Tanith of Gaunt's Ghosts that have been deafened by artillery fire communicate with a form of sign language.
 * In one of the Xanth stories, two characters learn American Sign Language as a way to communicate because a Xanthian girl cannot speak any known Mundane language. They later talk to a deaf man on the bus, because he saw them signing and thought they were deaf, initiating a conversation in American Sign Language.
 * In The Wheel of Time, the Aiel have a limited form of "handtalk", with the Maidens of the Spear expanding it into a more complete language.
 * In Dune multiple characters use hand signals to give orders to their subordinates. In fact, there are entire sign languages developed separately by the Atreides and the Harkonnens that allow them to communicate irrelevant information verbally and important stuff, with their hands, making sure that even if they are overheard, the enemy won't learn anything.
 * In Mirror Friend Mirror Foe, a ninja family is not only trained in that... They can communicate that way while having a verbal conversation on a totally unrelated matter.
 * The giant raccoons in Architect of Sleep use sign language to communicate due to having never developed a complicated enough vocal apparatus to support a spoken language. They do punctuate their signs with trills and chirps, though.
 * The Isitri from the Star Trek novel "Troublesome Minds" by Dave Galanter. They communicate by a mixture of telepathy and sign language, and have no spoken language (they have poor hearing, with many being deaf, and their throats and mouths aren't configured for verbal speech). The sign language is used by the few non-telepathic Isitri, and by all Isitri to communicate with aliens.
 * The telepathic treecats in the Honorverse communicate with humans via sign language, although they can understand spoken word fine.
 * Sword of Truth: the crypt workers in the People's Palace. Darken Rahl had their tongues cut out so they wouldn't speak ill of his father, so they developed one of these. Only their boss understands them at all, and poorly at that. He still has his tongue, primarily for this reason. Cara begins to follow what they mean after a length "conversation".

Live Action TV

 * CHiPs: they meet a deaf woman and learn sign language just in time to use it during a chase scene when they were far away from each other and there was construction noise nearby; then they never used it again.
 * Shows up a lot in NCIS as Abby and Gibbs both know ASL. Actually turns up again NCIS: Los Angeles when Abby is kidnapped and uses ASL to warn the local team about the room she's in.
 * The Korean Drama Can You Hear My Heart centers around several deaf individuals.
 * Switched at Birth has several deaf characters, and hence uses this a lot.
 * Sesame Street included Linda, a deaf woman who communicated entirely in American Sign Language during the course of the series.
 * The BBC has a magazine show for deaf people called See Hear, with presenters and interviewees using British Sign Language throughout. Until fairly recently the BBC would also repeat various prime-time shows in the early hours of the morning with an in-vision sign language interpreter for use as a teaching aid.
 * A children's show that aired in the late 90s/early 2000s called What's Your Sign? had one hearing host and one deaf host, and everything spoken was also said in ASL, to help teach kids sign language.
 * Similar to the Switched At Birth example above, Sue Thomas: F.B.Eye was about a deaf detective and included at least one other deaf character almost every episode.
 * The Heralds of the Heralds of Valdemar series not only have a hand-based signed language, but also a form of "Hand Signals" involving apparently playing footsie under the table for when they wish to communicate in secret.

Music Video

 * In the music video for Savage Garden's "Crash and Burn," Darren Hays sings and signs the final verse.
 * And for People who understand BSL, the video for Faithless' God is a DJ is pretty much sung and signed by Maxi Jazz. Only one small part with an argument being signed is not a direct translation.
 * Francois Pagny's Deliberately Monochrome video for "Savoir Aimer" (Know How to Love), consists of a single shot of him signing the lyrics of the song.

Tabletop Games

 * The Sisters of Silence from Warhammer 40000 use hand signals to communicate, one form for normal conversation and one for the battlefield.
 * Dungeons and Dragons.
 * Original D&D had "alignment languages", which included special signals and gestures. Granted, it had only 3 alignments. This was dropped after AD&D 1.
 * The Drow had a language of hand signs in their original appearance.
 * Forgotten Realms has mentions of "High Drow" sign language, corresponding to the old "High Drow" dialect. Also, the Sourcebook on Harpers mentioned their own "silent code" of gestures and expressions.
 * Star Wars saga edition had handsignals in one splatbook handled elegantly as a language. Well worth the cost, if you're playing that sort of campaign.

Visual Novels

 * Katawa Shoujo is set in a high school for disabled teenagers. One of the routes centres on the deaf-mute Student Council President, where she and her best friend communicates mainly in sign language..