In Ranma One Half, Principal Kunō's first name is never mentioned. Even an anime-only episode where a copy of one of the principal's old high school report cards is the keystone doesn't give it to us. Some people have taken "Kōchō" to be his name, but this is just Japanese for "Principal".
The Jusenkyō Guide pushes this to the extreme of everyone calling him simply "Guide" (or "Mr. Guide" if they're polite.) Plum, his daughter, calls him "Father", but that's it.
Cafe owners in anime are regularly addressed exclusively as "Master" (the English word), most notably in Witch Hunter Robin, where the Master of Robin's local cafe is a fairly important supporting character. It's apparently the standard in Japanese culture.
In Code Geass, the empress of China HAS a name, but in the series she's only ever called the traditional title of "Tianzi". Her actual name, Jiang Lihua, is mentioned in artbooks and magazine articles.
This is because in Imperial China, it was illegal to call the emperor by his given name.
The Captain, The Doktor and The Major from Hellsing. While there are fanon names for The Captain and The Major (Hans Gunsche and Montana Max respectively), they have never been officially named by Hirano within Hellsing canon.
Seras was originally only supposed to be known as "Police Girl" until the editors forced the writer to give her a name. Most people still only called her ''Police Girl, though.
Her name is known to both the reader/viewer and her team-mates however. It's Motoko Kusanagi. It's described as an "Obvious Alias" in the manga however. According to the creator, an English equivalent of her name would be something like "Jane Excalibur". Obvious alias indeed. Appropriately enough, the creator's own last name (Masamune) is also a type of famous sword.
While his superiors call him by name, Chief Aramaki is mostly just "Chief", or "that old ape-face" to his employees. Then there are the Redcoats who also never get their names mentioned, the Operators who have no real names, being androids, and Proto, whose name is more like a description, with him being a Bioroid prototype, and all.
Hokuto's lackey in Cromartie High School is known just like that. While he DOES have a name, every time he tries to say it, he is interrupted somehow. So, no one really knows his name. According to the DVD extras, even the original Japanese recording scripts only refer to him by this designation.
In Naruto, the Kages are addressed primarily by their title, which is often shortened to the ordinal (e.g. "Third Hokage" becomes "Third"), though they're still occasionally called by their actual names. Even the Kages themselves refer to each other primarily by title; apart from Tsunade and Gaara, we don't find out the names of the other post-Time Skip Kages until quite some time after their initial appearance.
We eventually find out the names of the first four Hokages; Hashirama Senju, Tobirama Senju (both sort of a spoiler), Hiruzen Sarutobi (his family name was revealed fairly early, but his given name wasn't revealed until the release of a databook that came out nearly a decade after the series started and isn't used in-series until even later), and Minato Namikaze.
This also holds true to the tailed beasts. Everyone refers to them by the number of their tails (Ex: Naruto's tailed beast is the Kyuubi/Nine-Tails); the sole exception to this is Gaara's tailed beast, introduced as Shukaku. Much later, it turns out that all tailed beasts have names; the only one that still adheres to this trope is the Juubi/Ten-Tails.
Soul Eater has Spirit, who is Shinigami's current Death Scythe. Almost everyone just calls him Death Scythe (apparently it's down to him being Shinigami's personal Weapon as opposed to 'just' a Weapon who has the rank of Death Scythe), including the other Death Scythes.
Except Stein (who calls him 'senpai') and, interestingly, Shinigami himself (who calls him Spirit).
Oddly seeing as he is Maka's (Spirit's daughter) partner, even Soul Eater didn't know Death Scythe's real name until Maka pointed it out during their battle with Stein.
Pani Poni Dash! in the dub. While the original Japanese version has him go by his rank, all the aliens refer to their captain as "alien captain." Also, the second episode starts out this way because Rebecca's too lazy to learn the names of her classmates, calling them by a significant trait they possess...except in the case of Kurumi Momose, who's distinguishing characteristic is that she has no distinguishing characteristics.
Happens quite a few times in Mahoujin Guru Guru. All but a few characters call Nike "Hero". Udberg Eldol is known almost exclusively as Old Kita Kita Man after his Kita Kita dance. Sly, already using a codename, is always called Boss. A slight subversion is Runrun, who Kukuri and Nike only know as the "Dark Magic Society Lady" because Runrun deliberately tries to keep them from learning her Embarrassing First Name.
The eponymous Index from To Aru Majutsu no Index is a living library who has memorized thousands of magical texts and can repeat them verbatim. Even her passport is signed as "Index Librorum Prohibitorum" (approx. "Forbidden Books' Index", in actual Latin) but no one ever questions what Touma points out to sound like an obvious fake name.
Interestingly, said passport reveals that Librorum Prohibitorum is actually her given name. Therefore, everyone's on Last Name Basis with her (except Misaka who's on a Hey You-basis).
Even Accelerator doesn't remember his given name, since he was studied for his ability to redirect and accelerate vectors since he was a small child.
As of Hoshimittsu, we know her name is Tsumugi, though nobody uses this name.
Master Asia from G Gundam, which is a Pragmatic Adaptation of his title, Touhou Fuhai (Undefeated of the East). His real name is never given in the anime, but the prequel manga Fight 7th gives it as Shuji Kurosu, meaning he's actually Japanese.
In Prince of Tennis Momoshiro tries to invoke this trope with Tachibana An, only ever calling her "Tachibana's Little Sister" ("Tachibana-imouto"). It isn't until she almost beats him in a game of tennis in order to snap him out of his angst at being dropped from the regulars that he actually calls her An. He then corrects himself, calling her "Tachibana's Little Sister", and she tells him to just call her An.
An episode of Gintama featured Kondou playing a barkeep known only as "Master" (roughly the Japanese equivalent of, well, "Barkeep"). It turns out that the nickname is actually short for "masturbation", due to his pelvic thrusting while mixing drinks.
Earl Ciel Phantomhive (Or Phantomhive-hakushaku in Japanese) is often referred to as simply Hakushaku by some characters. He's also just called "young master" or "bocchan" by all his house staff.
Ouran High School Host Club has Tamaki's grandmother, who for the longest time was only known as Obaa-sama, President Suou, or Suou Headmaster (the last two depend on the translators). Chapter 75 finally gives us a first name for her. It's Shizue. We're also given the Suou company's lawyer, Kousaka-san's, first name in chapter 75, over 20 chapters after her debut. It's Yuki.
The most mysterious of the Five Dragons in Yu-Gi-Oh 5Ds is usually referred to by fans as the "Fifth Dragon", because it hasn't surfaced as a card yet, and its true name still remains a mystery. In series itself, it hasn't been mentioned at all, but did make an appearance in a flashback and in the credits. Because of this, fans often poke fun at it by giving it wacky and unusual nicknames. It was later revealed to be "Life Stream Dragon", the true form of Rua's "Power Tool Dragon".
Similarly, though he is a very prominent minor character, plot device, and a sort of spiritual mentor whenever we need some Plot enhancement, Yusei's father, The creator of the Momentum system and designer of the first Momentum Reactor, the person who is said to have caused Zero Reverse, and yet saved Yusei Superman-style, is never referred to as anything except Fudo Hakase. It means Doctor/Professor Fudo, but some fans less versed in Japanese think its actually his given name.
The Class President in Seto no Hanayome, who is never referred to as anything but "Class President". It's even a minor point of characterization for her, as she's a bit depressed that no one actually knows her name.
In the same series, Lunar's dad is almost always just referred to as "Lunar's dad".
Kaede's mom and dad in Ninin Ga Shinobuden, who are never referred to as anything other than "Kaede's mom" and "Kaede's dad".
In Pokemon 2000, the Collector has a name — Jirarudan. But it's only given in the program book given out at Japanese theaters. The English closed captions refer to him as Gelarden, an acceptable romanization of the original, but it's still not said aloud and he still only ever refers to himself as "a Collector".
Uranai Baba of Dragon Ball. The name means "fortune-telling crone". Guess what she is and what she does.
Dragon Ball loves this trope. Muten Roshi, "Invincible old master". Kami-sama, "God". Kaio-sama, "Lord of the Worlds".
Android 17 and Android 18 of Dragon Ball Z were once human, but their real names are never revealed.
In Death Note, Light is known to the world only as Kira. It's from the English word "killer". Because he kills people. Yeah.
A far more literal example is poor Watari, whose name derives from watashiyaku (渡し役), meaning "handler" — because he manages and takes care of L.
Jyu Oh Sei has Third who is named such because he's third in command in his tribe. A bit of a subversion in that he actually insists that people call him this, and never discloses his real name (until the end), claiming that he had forgotten it.
Medabots has Mr. Referee. It even goes so far that he calls himself Mr. Referee everytime he pops up.
In Penguin Revolution, the president of Peacock's name is Hidemitsu Torii, but everyone - even his son and adopted son, who are both employed by Peacock as talents - calls him "President."
In Hekikai No Aion, Seine is frequently called a witch instead of her real name.
The Idolmaster - The Producer, which is what the characters will call the player character in the games. As a side effect and subsequent running gag, the rest of the franchise, be it show, or comic, he's still always called Producer even when having an actual name would be justified and make more sense.
The Professor in Nichijou is only ever referred to as "The Professor." Her family name seems to be Shinonome, but her given name has never been revealed.
In Saiyuki, 'Sanzo' is technically the name of the priestly order appointed bearers of the Sutras from the Dawn of Time, not the given name of one of the main characters. His Buddhist dynastic name, the closest thing he has to a first name, is "Genjyo" but it's rarely used except as part of his title or to distinguish him from other past or present members of the Sanzo priesthood (i.e., Koumyou or Ukoku). Goku was the first person to use "Sanzo" as if it were a personal name instead of a rank, because that was the only part of Sanzo's long-ass full title he could easily remember. Hakkai and Gojyo later picked up on this habit of Goku's when they met Sanzo.
Tadakuni's little sister Mei is always referred as "little sister" (imouto), even by people other than Tadakuni.
Sanada North Prefectual's Student Council President and Vice-president, and their counterparts in Central Prefectual, are only referred by their titles.
We never learn the names of most characters from Jinrui wa Suitai Shimashita, so this trope is pretty much expected. Oddly, it applies more to the side characters, as Assistant is the only one of the three main characters to have a consistent 'name'.
In Maiden Rose, Klaus and Taki spent a fair chunk of the Luckenwalde doujinshis at a bar in the town. Despite usually being his only customers, the owner is never referred to as anything but "barkeep".
From Nextwave, the Captain. According to Aaron Stack, if the Captain ever had a real name, he's forgotten it. (He is not actually the captain of anything.)
It is later revealed he'd tried everything, including Captain ☠☠☠☠ ('☠☠☠☠' being an unspecified but extremely rude word), but had been sued and/or beaten up by Captain America until he settled on The Captain. And he still had to pay "some Marine-looking melon-farmer" royalties.
The book's theme song, when describing each character's notable trait, includes the words "The Captain! / ...HIS NAME IS THE CAPTAIN!" (while describing, for instance, that one other character "Is going to microwave your ass").
Fall Out Toy Works has the Toymaker. As for his real name, the synopsis for the second issue had it as Jasper, one of the data files Mr. Moth brings up in the fourth issue has his name as "Chris Toymakeras". The final page of the final issue reveals his name is actually Alistair and brings up the possibility of his last name actually being Toymaker.
In the Transformers comic series "The War Within: The Dark Ages", a character is introduced who is only ever referred to as "the Fallen," as his name was taken away from him by his fellow Transformers after he betrayed Primus and sided with Unicron.
His name used to be Megatronus Prime, and he was one of the original Thirteen before becoming The Fallen.
The Beano extends this to relatives of the characters so named - The teacher of the Bash Street Kids is called "Teacher" and his wife is "Mrs. Teacher". Similarly, one strip features the headmaster's brother - Mr. Headsbrother.
The comic once claimed in response to a reader's letter that Dennis the Menace's father was actually named "Dennis's Dad" at birth, and knew he had found his future wife when he met a girl called Dennis's Mum.
The Adventures of Tintin's constant companion is known only as Captain Haddock until the second last comic in the series, and Tintin rarely refers to him by anything else than simply Captain. In said comic, the Captain's first name is revealed to be Archibald.
The Smurfs don't have names, but refer to one another by their most prominent personality trait: Brainy Smurf, Handy Smurf, Grouchy Smurf, etc. This gets taken to the extreme in the live-action movie with the mention of Passive-Aggressive Smurf.
Used in a significant manner in V for Vendetta. The Head is only referred to by title for the bulk of the story... but people start referring to him by his actual name once his Villainous Breakdown causes a loss of faith in him.
In Calvin and Hobbes, Calvin's parents are never referred to by name, only "Mom" and "Dad" by the titular characters.
As a result, the character of Uncle Max was short-lived because Bill Watterson realized it wouldn't make much sense for him to never refer to Calvin's parents by name (during his appearance, he referred to Calvin's dad as "bro").
Much of the cast of The Wizard of Id are referred to only by their title or job description: the King, the Wizard, the Duke, Turnkey, Lackey...
In W.I.T.C.H., everyone refers to the Oracle as Oracle. Which leads to trouble while asking who was elected Oracle. ("What's the Oracle's name?" "You just said it"). A fallen Oracle is even unable to remember his name.
The Beast from Transmetropolitan. He presumably has a name but it's never shown on-screen, and claims everyone just calls him "The Beast" — including his own kids.
In the Horseshoes and Hand Grenades sidestory Wheel of Fortune, Mei Shirakawa's male 'friends' are simply known as Ros and Guil because she always keeps forgetting their names. This also extends to the forums she visits and when they're killed off, Renenutet doesn't even bother to even reveal what they are.
In The Polar Express, the credits list the main characters as "Hero Boy" and "Hero Girl."
A bit of a Genius Bonus from Mulan is that if one cross-references the storyline with history and myth and accepts that the "Huns" in the film are actually the Xiongnu, the Big Bad is in fact never referred to by his name but by his TITLE, as Shan Yu means "Majesty Sun of Heaven".
Doctor Facilier, the main villain of The Princess and the Frog for some reason, is always referred by everyone in the film as "The Shadow Man."
Also, according to Word Of God, Evangeline (the Evening Star and Ray the firefly's love interest) is actually the Blue Fairy's real name.
The Big Bad of Disney's Dinosaur for some reason, is always referred by everyone as "The Carnotaurus." Guess what dinosaur he actually is! (hint: it's not the one you expect)
It's probably because, unlike the herbivores, the two Carnotaurs are unable to talk.
The Pirates! In an Adventure with Scientists takes this trope to its extremes by applying it to the entire main cast. The Pirate Captain leads a crew consisting of The Albino Pirate, The Pirate With Gout, The Surprisingly Curvaceous Pirate, and various others. Assuming they have actual names, we never learn what they are. The only crew member with a revealed name is Polly, their pet Dodo.
Films — Live Action
In Kill Bill the protagonist is known as The Bride. Later, she is called by the nickname Kiddo. Only later do we discover her real name is Beatrix Kiddo, but she is still called The Bride in the credits. The second film adds "a.k.a. Black Mamba a.k.a. Beatrix Kiddo a.k.a. Mommy"
Lucky Number Slevin has major characters named The Rabbi, The Fairy and so forth. When anyone asks why they are called what they are, the answer invariably is "because he is one".
In the Jurassic Park sequel The Lost World: Jurassic Park, when the Tyrannosaurus rampages through the streets of the city, one poor man makes a failed attempt to get into a building and becomes lunch. He's forever memorialized in the credits as "Unlucky Bastard." Talk about truth in advertising...
This character is played by David Koepp, who wrote the screenplay and therefore named this character as well as playing him.
Repo! The Genetic Opera abounds with these characters — Grave-Robber, Single Mother, Band Leader, News Reporter, and the Repo Man all count.
In Australia, Hugh Jackman's character is only called the Drover.
The Feast series rarely gives the main characters actual names; no names are ever mentioned in the dialogue and the in-film bios and the credits just use nicknames ("Hot Wheels", "Shitkicker", "Secrets", etc.) or just refer to the characters by what they are ("Heroine", "Bartender", "Bossman", etc.)
During Freddy's rampage at the pool party in A Nightmare on Elm Street Part 2: Freddy's Revenge, one of the partiers tries to reason with him, and we're treated to a sequence of the guy treating Freddy like some kind of animal while trying talk him down ("It's okay, nobody's gonna hurt you"); Freddy hurls the guy at a barbecue, which blows up when the kid hits it. The credits just list the character as "Do-Gooder".
None of the characters in The Driver have names. In the credits they're listed as The Driver, The Detective, The Player. etc.
Hilariously used in Rock N Rolla, with the Councilor, to the point when another character gives him something and says "It has your name on it", it actually says "The Councilor".
Many of the characters in The Fall, including the Indian, the Black Bandit, and "the actor with only one leg".
The character Charlie Chaplin played in most of his films was usually just called "The Tramp", as well as being an example of The Tramp.
The majority of characters in Cemetery Man refer to Francesco as "Engineer". Nobody calls him by his first name, except perhaps Franco.
The coffee shop owner in Pulp Fiction is credited as "Coffee Shop" due to his only line in the film being "I'm just a coffee shop—" before being interrupted.
The Butcher and the Postman in Delicatessen constantly refer to each other as "Boucher" and "Facteur" (it's a French movie).
In the Russian film Stalker by Andrei Tarkovsky the three main characters are Stalker, Writer, and Professor, each named for his profession. The viewers are never told their "real" names.
In Robocop, the head of OCP is simply referred to as the "Old Man."
Though they are given names in the film proper, marketing for Inception referred to the main characters by their role in the heist (The Extractor, The Architect, The Tourist, The Mark, The Shade, The Point Man, and The Forger).
In The White Ribbon, children have names but adults only referred as The School Teacher, the Doctor, the Baron, etc.
In Bicentennial Man, the robot butler Andrew calls his human owners Sir, Ma'am, Miss and Little Miss. The characters are also listed that way in the credits. Everyone except Ma'am has their name said out loud at some point, but it's easy to miss.
In Waterworld, the main character is known only as the Mariner. Subverted in the extended edition, wherein after the heroes reach Dry Land, Helen gives the Mariner a real name just before he heads back out onto the ocean. It's "Ulysses", the name of the sailor who was the main character of Homer's Odyssey.
This trope is used to powerful effect in D. W. Griffith's Intolerance, causing the characters to become allegorical and thus universal (although some of them are historical figures).
Zombieland: all the main characters call themselves after the city they are from instead of their names.
Hocus Pocus: Max is repeatedly called "Hollywood" by Salem, Massachusetts, delinquents Jay and Ernie (sorry, Ice) because he has recently moved to Salem from Southern California - and in Jay and Ice's minds, the only important thing about Southern California is Hollywood. (And the fact that "Holly" is a girl's name might also be a factor, in humiliating Max.)
Lady from The Quick and the Dead. She has a real name, but nobody in the town knows it and the audience doesn't learn it till quite late in the movie.
The title character of El Mariachi is only known by that name, even in the sequels where he can no longer play guitar. By Once upon a Time in Mexico, people treat it like it's his real name and shorten it to "El."
Very few characters in Robinson Crusoe and its lesser-known sequel are given proper names, with the exception of Friday and a couple others. Instead we have "the Spaniard," "the captain," "Friday's father," "my wife," etc.
The White Witch note who, confusingly, is also called "the Queen" and "the Witch" actually gets a name—Jadis.
Caspian's wife is never called anything but "Ramandu's Daughter."
The entity who created the Land in the Chronicles of Thomas Covenant is only ever referred to as "the Creator" or as "The man in the ochre robe."
Gods in this setting seem to have a descriptive title as their "true" name; there's also the Despiser and the Lover, though both of these are given other names by mortals and as such don't fit the trope as well.
Subverted in Jim Butcher's The Dresden Files. When Harry meets The Archive in Death Masks, a little girl who possesses the sum of all human knowledge, he insists on giving her an actual human name: Ivy.
Small Favor reveals that some in the White Council believe this to have the potential for some dangerous consequences.
Given the power that names have in the Dresdenverse, the White Council might be right. Stating a person's true name (and pronouncing it exactly as that person would) grants absolute power over the person whose name is being spoken. Now, Harry has named three extremely powerful entities in the Dresdenverse: the shadow of the fallen angel Lasciel, whom Harry names Lash; an air elemental that resides in a skull, whom Harry calls Bob; and The Archive, whom Harry renamed Ivy. The first elected to sacrifice her existence to save Harry; the second managed to fight off a spell cast by an evil former master, Kemmler, and help out Harry. It will be interesting to see if Harry's naming of Ivy has any impact in the future.
At this point he has also named Demonreach, a sentient island and a nexus/origin of leylines. That one has been more or less explicitly stated by the Gatekeeper to have been a really stupid move.
At first glance, the Gatekeeper himself also seems like this, but at one point someone mentions that his name is Rashid.
Again, at first glance, there's Chauncy, a demon Harry summons for information on occasion. The demon's True Name is actually Chaunzagorath (Or something along those lines), which is a bit of a mouthful, so Harry probably calls him Chauncy for the sake of not having to pronounce his name.
Conrad's Heart of Darkness only has three characters that have names (Marlow, Kurtz, and a minor character called Fresleven). Others include the Narrator, the Accountant, the Manager, the Director, the Director's Uncle, the Pilot, Kurtz' Mistress, Kurtz' Intended, Marlow's Aunt, the Russian, etc.
Terry Pratchett's Discworld has the Librarian of Unseen University, simply named "The Librarian". In his case, he actually takes great pains to hide his real name (apparently Horace Worblehat) in order to keep the staff of Unseen University from turning him back into a human, since he prefers his current orangutan form. Just don't call him a monkey.
Most of his faculty colleagues just go by their job descriptions as well, such as The Dean, The Lecturer in Recent Runes, and the Bursar. The Bursar's real name has been given as Arthur A. Dinwiddie ("That's Dinwiddie with an o."), but it's rarely used. This was lampshaded in The Last Continent.
"One of us must know his name, surely? Good grief, I should hope we at least know our colleagues' names. Isn't that so..." he looked at the Dean, hesitated, and then said, "Dean?"
According to the latest (2009) Discworld novel, Unseen Academicals, the Dean's first name is Henry. Ridcully at least has the excuse with regard to the Librarian that he was away from the University for 40 years and didn't know him before his accident. The Dean even uses his title to refer to himself. In Soul Music he monogrammed onto a leather jacket.
In The Alchemist, almost every character is referred to by their occupation (the titular alchemist, the crystal salesman, etc.), and only a select few characters actually have names (including the main character, Santiago the shepherd, but even he is victim to this trope; his name is only mentioned in the first line of the book and he is simply referred to as "the boy" afterward).
It could be an allusion to Ernest Hemingway's The Old Man and the Sea, for the main character's name was also Santiago, but he is almost strictly referred to as 'the old man' throughout the novel.
"The Old Man", erstwhile owner of "The Tell-Tale Heart" in the Edgar Allan Poe's story of the same name.
In one of Rick Cook's Wiz Biz novels, the main character asks his wife "What's his name, anyway? Everyone calls him Dragon Leader." His wife replies "Ardithjanelle. It means 'Shy flower of the woodlands.' It seems his parents were expecting a girl." The main character decides just to call him Dragon Leader.
In Jose Saramago's novel Blindness, none of the characters have a name. They are referred to by their profession or physical appearance.
In the classic Japanese novel The Tale of Genji (which is considered by some to be the first modern novel), characters, especially women, are only referred to by titles, descriptions, and honorifics; their actual names are never mentioned. (Doing so would have been considered very rude.)
Chaucer's pilgrims in The Canterbury Tales are never given names. They're merely identified by their position (The Pardoner), Occupation (The Miller), or status (The Wife of Bath, The Knight). There are only two exceptions:
Diane Duane's Young Wizards books have the Lone Power—the other Powers we meet seem to have actual names, but the Lone Power is only ever referred to as such or by the name some specific culture calls It.
Justified Trope. Naming any Power in the Young Wizards books seems (probably a deliberate move on Duane's part) to be like naming a god in certain real cultures: even if you can obtain and pronounce Its true name the sheer extra-dimensionality and, well, power that comes with invoking such a name will probably kill or injure you in the process. However, the two main characters manage to speak the true name of the Lone Power once, while at the peak of their power as wizards. Mainly because being able to speak someone's truename allows them to alter it; this allows the main character to open a path for the Lone Power's eventual redemption.
The main Caucasian family in Ragtime are only referred to by their designation within the family — "Mother", "Father", "Mother's Younger Brother", "Grandfather". When this was adapted to musical theatre form in 1998, "The Little Boy" was given the name of Edgar (named after E.L. Doctorow, who wrote the novel).
Similarly, the Jewish immigrant family is referred to as "Mameh", "Tateh", and "The Little Girl," the former two being Yiddish for "Mother" and "Father." Aside from the Walkers, almost everyone in the novel with a name is an actual person.
In Mickey Zucker Reichert's The Last of the Renshai series, there is a character that goes by "Captain" who is, in fact, a captain of a ship. When other characters ask for his real name, he says that "Captain" is his real name, because it's the name he uses for himself. Although Frey does eventually reveal Captain's original name.
H. G. Wells's The Time Machine has a framing story of the Traveller telling his tale to a group of men. Apart from Filby, all are identified by their description: The Editor, The Provincial Mayor, The Medical Man, The Time Traveller and so on.
In Stephen Baxter's authorised sequel, The Time Ships, the Traveler refers to his friend the Writer ... who is clearly H. G. Wells, but never named as such.
The Kzinti in Larry Niven's Known Space universe do not have names until they earn them through acts of heroism or importance, although they can earn partial names that combine a real name and their rank or role. Until then, they're known by their rank or role, or familial relations until they've gained a role of some sort: Short-Son of Chiirr-Nig, Flyer, Engineer, Telepath, Speaker To Animals (diplomat to aliens). Speaker earns his name (Chmeee) after returning from the Ringworld. The Kzin captain in "The Soft Weapon" has a "partial name", Chuft-Captain. He doesn't get a chance to upgrade it later, being killed by the titular weapon's Self-Destruct Mechanism.
In Larry Niven's The Magic Goes Away series, the Warlock was so powerful that his nickname became a name for all wizards. Much like Harry Dresden, names in the Magic Gone Away world had power, so he took steps to prevent it. He was so powerful and so old that he had induced mutations in humanity such that no-one was even able to pronounce his real name anymore.
The Rostov children's uncle in War and Peace is only referred to as Uncle.
Kyrie's boyfriend in House of Leaves is only ever referred to as "Gdansk Man", Gdansk being the city in Poland he was born in.
The Ellimist in the Animorphs books has three names: his real name, his "chosen" name, and his "game" name. Ironically enough, his game name is the one we're familiar with; his chosen name is rarely-used Toomin, and his real name is the even more rarely used Azure Level, Seven Spar, Extension Two, Down-Messenger Forty-one. Makes sense, huh?
And the Drode. According to the... er, being himself, it means "wild card."
The Redwall book The Bellmaker features a baby mouse who is only ever referred to as "mousebabe". Brian Jacques, when asked what the mouse's real name was, responded "Didn't you ever know a family who always referred to the baby as just 'the baby'?"
In most likely every book in the series, there's also at least one otter character whose title is "Skipper of Otters", and is referred to throughout the book as "Skipper", though they all probably have their own names. There are also the Gousim Log-a-logs, which have their own names but are normally referred to as "Log-a-log So-And-So."
Fool by Christopher Moore has a royal food taster whose actual name is Taster. Several of the nobles are also referred to solely by their titles as well.
In Stanislaw Lem's novel Eden, the characters (the crew of a spaceship) are only referred as the Captain, the Engineer, the Doctor, the Chemist, the Physicist, and the Cyberneticist.
Lem subverts his own convention halfway through the book, when in the only scene dedicated to character development, The Doctor gets a name - Henry.
Lords of the Bow includes a nameless assassin and spy who infiltrate the Mongol camp during the siege of Yenking. The spy goes by the name Ma Tsin, though this is a pseudonym, and the sections told from his Point of View only ever refer to him as 'the spy'. Bones of the Hills features the Old Man of the Mountains, imam of the Assassins.
In the original novel The Phantom of the Opera by Gaston Leroux, there is a rather plot-central character known only as the Persian. He was, however, cut from Andrew Lloyd Webber's musical based on said book, with Madame Giry somewhat taking over his role.
Done frequently and hilariously in Catch-22: Nately's whore, Nately's whore's kid sister, Nately's whore's pimp, the Texan, the Soldier in White, the Soldier Who Saw Everything Twice, the C.I.D. Men, the Maid in the Lime-Colored Panties, and Dreedle's Girl.
In Shogun, only the ruling class have actual names: everyone else is called things like "Old Gardener" (except prostitutes who take the names of flowers.) The protagonist ends up being called Anjin-san, which is a polite way to refer to his job as Pilot of a ship.
The alien subject named "Subject" from Blind Lake. Done deliberately by the scientists who named it to avoid the temptation to anthropomorphize it.
The Mouth of Sauron from The Lord of the Rings is only ever referred to as the Mouth or the Messenger (both titles descriptive of his role in Sauron's hierarchy — he's the one who takes Sauron's words and relays them to both minions and enemies). This is because he gave up his real name so long ago that even he has forgotten it.
Gandalf revealed his real name (Olórin) to very few people in Middle-Earth, so he's mostly known by the the descriptive names he's been given in various languages: Mithrandir ("Grey Wanderer"), Gandalf ("Wand Elf"), and so on. At a few points, people who're asked whether they know Gandalf say that they don't know his real name, and just call him what everybody else does.
At the beginning of Fellowship of the Rings, Aragorn is known to most as "Strider."
Farmer Maggot's wife is never referred to by name.
In The Hobbit, neither the Elvenking or the Master of Lake-Town are named.note Fortunately, since The Hobbit wasn't written to be part of Middle-Earth, and the use of real Norse names for the dwarves necessitated a complicated scheme in The Lord of the Rings in which dwarves never reveal their real Dwarvish names to outsiders, instead adopting "outer names" in nearby human tongues, which were themselves "translated" by Tolkien into Old Norse. Imagine if the human and elf characters had to receive the same treatment! In The Lord of the Rings the former's name is revealed to be Thranduil.
Throughout The Lord of the Rings and The Silmarillion, Círdan the Shipwright's real name is never once uttered. "Círdan" just means "shipwright" in Grey Elven. Even back in the First Age, most elves didn't actually know the guy's real name, it hadn't been used in so long. Towards the end of his life, Tolkien wrote that some Grey Elves speculated it was Nōwē.
Gabriel from the Wicked Lovely series. The leader of the hounds is always the Gabriel. It's a name of rank, not birth.
Not always, or at least, there's a Distaff Counterpart. When Ani talks about wishing to succeed Gabriel, she says she wants to be "Their [the hounds] Gabrielle." Gabrielle being the female form of Gabriel.
There are three characters in Alice in Wonderland with names; Alice herself and the White Rabbit's servants, Pat and Bill. (There's also the Rabbit's maid, Mary, and Alice's cat Dinah, but they don't actually appear). The rest are only known by their species (the White Rabbit, the Cheshire Cat, the Mock Turtle etc.), their title (the King, Queen and Knave of Hearts, the Duchess) or their profession (the Hatter, the Cook, the Footmen).
Daemon gives us The Major, who is never known by any other name. Turns out, he's not even a Major in any branch of any military, though it seems he used to be.
In Andy Hoare's White Scars novel Hunt for Voldorius, an in-universe example: Voldorius refers to Skall solely as "the equerry".
At the end of the first Inheritance Cycle book, Eragon gets a telepathic message from someone called "The Weeping Sage," or "The Cripple Who Is Whole." Subverted in that in the next book, we find out his name is Oromis.
The Big Bad of the Fablehaven series is always called "the Sphinx" (or "the Ethiopian" at one point). He's not really a sphinx, he's just called this because he's full of riddles and mysteries.
In Robert A. Heinlein's —All You Zombies—, the narrators is only referred to as "the barman," but is at the end of the story revealed to be the same person as the other characters, originally called Jane.
The emperor in Detectives in Togas is mentioned several times, but never by name. From the dates given in the story, we can conclude it's Tiberius, second Roman emperor.
In C. S. Lewis's Till We Have Faces, the King is known only as the King, except for once in the beginning when his name is given as Trom. Similarly, the first priest of Ungit is only ever the Priest.
The characters in The Annals of the Chosen are either known by their profession or a meaningful nickname. For example, the titular Chosen are generally known by nicknames based on their role, such as the Leader being Boss and the Swordsman being Blade or Sword.
In Chuck Palahniuk's Fight Club the main character never gives his proper name. He is referred to as one of the many aliases he uses in his support groups and later in the film/book he is referred to as Tyler Durden, but his true name is never told to us. In fact, he is only listed as The Narrator in the credits for the film.
The main character and narrator of The Diving Universe is known only as Boss, neither giving nor using her real name.
The woman in yellow in Dirge for Prester John, called Theotokos, which is clearly not her real name. She is an authority figure, but how literally we should take this title is unclear as yet.
In Black Prism we are briefly introduced to a pirate shooting a musket at the protagonists. One of the protagonists recognizes him as a rather famous marksman who most people know simply as Gunner. At the end of the book, after his ship is sunk, Gunner has control of the only working lifeboat and decides that a promotion is in order so he requests that his crew call him Captain Gunner.
The man that Katniss bought her sister's goat from in The Hunger Games is only known as the Goat Man.
The children in The Fire-Us Trilogy had their brains rather scrambled by trauma and forgot their real names. Some of them chose names that fit the roles they took after the virus. Hunter "hunts" for supplies to scavenge from houses and stores. Teacher gives the younger children lessons on the world before the virus, and Mommy takes care of them.
The old Provincara from Chalion is never given a name, not even by her daughter or brother.
In American Gods, Shadow's real name is never mentioned. Late in the story, he gives it to Bast and apparently goes without from then on. In the sequel novella Monarch of the Glen, Shadow's name is revealed to be Baldur Moon.
Professor Mmaa's Lecture has Dr. Arsene's Private Detective, Professor Soul's First Assistant and Professor Soul's Second Assistant.
In the Light Novel version of The Slayers, Lina's home country is ruled by a demigoddess known only as the Eternal Queen.
In the Black Company novels, wizards are either known only by a title that describes their position and powers or Only Known by Their Nickname, since a wizard's true name holds power over them and can even be used to strip their magic away. The Dominator, the Lady, Soulcatcher, and Shapeshifter are all examples of the "known by a descriptive title" version.
The Seeker and Doc from The Host. Regarding the latter; Wanda actually asks him why that is, and it turns out he finds his real name embarrassing. It's Eustace.
Everything's Better With Elves: Laura and Kim are the only humans with names; everyone else is known by various descriptions, most prominently the girl with improbably long hair, and her roommate, mostly called the "Elf Goddess".
In Even the Wingless Chatcaava don't put much value in names, thus the highest ranked ones are known by their titles. Emperor, Slave Queen, Second, Third, etc.
Pilot from Farscape. He (and other members of his race) have names the translator microbes couldn't cope with.
The Janitor from Scrubs — he even calls himself that. In the final episode, he tells J.D. his real name is Glenn Matthews.
But unfortunately as soon as J.D. leaves, an orderly walks by and says "Hey Tommy.".The Janitor responds with "What's up?", thus leaving his true name a mystery. That is, until Word Of God confirmed that the Janitor was telling the truth for once.
In the first Star Trek: The Original Series pilot, "The Cage", Captain Pike's second-in-command is only addressed as "Number One" (i.e. first officer). It's uncertain whether this would have persisted had that version of the show become the actual series.
A novel by D.C. Fontana claims she hails from a planet where everyone is genetically engineered, and her name actually is "Number One".
Star Trek: Voyager has the Emergency Medical Hologram, but since that was too long, they just called him The Doctor, which he kept for the entire series despite frequent prodding by other crew members to come up with a name (and the occasional Reset Button when an episode had him adopt one on his own). In his case, it was because he had a computer's knowledge of languages, and everything he liked the sound of tended to mean something offensive in some language or another.
He did eventually decide on a name for himself in the series finale: Joe. However, the timeline in which he decided on this name was negated by Voyager coming home.
For that matter, The Doctor from Doctor Who. As well as several other Time Lords like The Master, The Rani, The War Chief, and The Meddling Monk. Most known Time Lords do have names, but losing the right to use it seems to be an intrinsic part of becoming a Time Lord Renegade.
Drax seems to get away with using his real name, but then again, he isn't nearly as big a troublemaker as the other Renegades.
The Doctor Who Expanded Universe has given names to all the renegades... except the Doctor. The Monk is Mortimus, the Master is Koschei, the War Chief is Magnus and the Rani is Ushas. All we know about the Doctor is that he used to be called Theta Sigma, or Thete - but that isn't his actual name.
However, it's not exactly clear whether the above mentioned names are the characters' real names, or nicknames that they gained in the Time Lord Academy.
It's also worth noting that Magnus first appeared in a DWM comic strip, where the intent seemed to be that he was the Master. Then David McIntee named the Master as Koschei, and Gary Russell attributed Magnus to the War Chief to tie everything up.
Interesting, even at the time a letter to DWM pondering whether Magnus was the Master or the War Chief was met with an enigmatic "You're right, it is one of those."
When the Doctor encounters a woman from his own future whom he has not yet met, his future wife, she convinces him that he will one day trust her implicitly by whispering his true name in his ear.
Also from Doctor Who, Brigadier Alistair Gordon Lethbridge-Stewart is almost always referred to as simply The Brigadier.
The episode "Midnight" lampshaded the fact that one character who sacrifices herself to save other people was only known as "the Hostess".
In "The Doctor's Wife", the Doctor receives a message from a Time Lord named the Corsair. Turns out it was a trap. He finds the arm of the Corsair, though.
In fact, it has been revealed that the oldest question in the universe, the one the Doctor has been running from his entire life is "Doctor Who?"
Gilligan's Island had the Skipper and the Professor. (And Gilligan, too, although that at least was the character's actual last name.) Technically, they have names. It's just that they aren't used outside the pilot. The Professor is "Roy Hinkley", and the Skipper is "Jonas Grumby". There is no official word on Gilligan's first name, but the fan rumor is "Willy".
Chief Petty Officer Galen Tyrol on the rebooted Battlestar Galactica wasn't referred to by his full name until well into the series — even his lover, Sharon Valerii, calls him "Chief". Word Of God was originally she was going to use his name when she was shot but his name had not been mentioned before and they didn't want people suddenly being jerked out of the moment by his being referred to as Galen for the first time. Even after he is later demoted several people call him Chief, probably by force of habit.
Similarly, most of the pilots are rarely if ever called by anything except their call signs; even Helo's lover (... also Sharon Valerii, but a different one) calls him Helo. Hence the subtle power of the scene where she is given the call sign Athena. It shows that the pilots now understand she is a different person to Boomer (the origonal Sharon Valerii) and have accepted her as one of them despite the fact that they know full well she is a Cylon.
Government ministers on Spooks are consistently referred to by their titles, even semi-regular characters like the Home Secretary.
Ned from Pushing Daisies is always referred to by the narrator as "The Pie Maker" (and "Young Ned" in childhood flashbacks), although most of the characters in the show do call him by his first name. His last name hasn't been given.
Frequently in the series, Ned's love interest Chuck is referred to as "Dead Girl" by Emerson Cod.
In Sabrina the Teenage Witch, Sabrina always calls her Quizmaster... Quizmaster. She later finds out in one episode that his name is Albert, and she remarks that she always thought his name really was Quizmaster and the fact that it was his occupation was just a happy coincidence.
Earl always refers to Darnell on My Name Is Earl as "Crab Man", and his relatives (or pets) as "Crab Man's (insert position of relative or pet)".
Lieutenant Murtagh from Family Matters had his first name name legally changed to "Liuetenant." When he told this to Carl, and Carl asked him what his name was before the change, he answered that it was "Sergeant."
Nursie in Blackadder II, sort of. She certainly goes by her title, even though it's not even role she properly fills anymore (granted she continues to do so anyway) but she does admit her real name as being Bernard.
"The Host" had been appearing for nearly a full season on Angel before we learned his name was Krevlornswath of the Deathwok Clan, Lorne for short.
Not only the audience, but the main characters as well. They never bothered to ask.
In The X-Files, the Cigarette Smoking Man's first name was never revealed, and he didn't even get a last name or initials until midway through the sixth season. Many other significant characters are only given descriptive names like "the First Elder" and "the Well-Manicured Man."
Many of the White Lodge and Black Lodge residents in Twin Peaks are known only by a title- "The Man From Another Place", "The Giant", etc.
The main antagonist for the first two seasons of Supernatural is known only as "The Demon" for the first season, which is expanded to "the Yellow-Eyed Demon" for the second (out of necessity after other demons started showing up). His real name, Azazel, was only revealed four episodes into the season after his death.
In the Leverage episode "The Bottle Job", the villain Mark Doyle's two henchmen are repeatedly introduced as "Liam" and "Liam's Brother".
Mike Chang from Glee, despite actually having a name, is known both in-universe and out almost exclusively as "Other Asian."
Not anymore. Since he an Tina got together in the second season, he's been given more screen time and more character development.
Mystery Science Theater 3000 gave us "Brain Guy", whose official name was actually "Observer", even in the credits, for quite a while. Eventually "Brain Guy" stuck, though, especially when he was forced to confront his former fellow Observers in favor of humanity.
The Duke of Cornwall in the 1998 Merlin series. His name in the actual legends is usually Gorlois or Hoel, or sometimes not mentioned. In this series, however, he is simply referred to as "Cornwall". Made even stranger in the novelizations, where the name Gorlois was attributed to him, but many characters continued to call him Cornwall.
Starburns in Community. His real name is Alex Osbourne, but good luck getting anyone to remember that.
Agent 99 in Get Smart is always referred to as 99.
In the episode where she and Max get married, her real name is presumably said during the wedding vows. But a wedding guest gets bored and falls asleep and his snoring drowns out that part of the vows
In season one, The Chief's first name is revealed to be Thaddeus. But he's usually just called "The Chief" or "Chief"
The main characters of Backup all work closely together in one police response van. Thus Sergeant Parkin is just Sarge, Susan Li is called Bruce, ditto Token, Oz, Thug, Flub, Dippy etc etc. When Bruce has been temporarily in command, she is called up over an incident involving PC Barrett. If it wasn't for the scene immediately afterward when Thug is being asked questions about the same incident you'd probably never guess who Barrett was.
In the TV adaptation of James Clavell's The Children's Story, the new teacher explicitly tells the children to call her "Teacher" whenever they ask her name. (In the original book, the narrator refers to her throughout as "the new teacher", but she does tell the children her name when asked — the narrator just doesn't say what that name is. Clavell wanted her to represent an idea without being specifically tied to a particular nationality or ethnicity.)
Several characters on The Muppet Show are known by their titles/professions only. Famous examples are the Swedish Chef and the Newsman. (An Overly-Long Name was given for the Swedish Chef by the guest star in one episode, but it was very possibly a joke.)
La Femme Nikita: Apparently by official policy, the head of Section 1 is referred to as Operations and addressed as "Sir", except sometimes by Madeleine, who is of very high rank, and George, whose position outranks Operations.
In Entourage, Ari's wife is always referred to as "Mrs. Ari Gold" and her first name is never mentioned until the final season (it's Melissa).
Batman TV Series: Miss Iceland from Green Ice / Deep Freeze is never known by his real name.
Subverted in the Wizards of Waverly Place episode "My Tutor Tutor", which introduces a tutor whose name is Tutor. Apparently this is a common practice in the wizarding world, where parents name their children what they hope them to be. This doesn't always work, though, in the case of Dr. Butcher.
For the longest time in Heroes, Noah Bennet's mysterious associate was known simply as "The Hatian". Claire later reveals that his real name is René.
As seen in the page quote, the first barkeeper on Cheers was known as "Coach" because he was Sam's coach when he was a major-league pitcher.
Even more important character in the Bible: God, who goes by His title ("God" or "Lord") as opposed to His name ("Yahweh," "Jehovah," or the nearest transliteration depending on the alphabet) in most translations.
ECW wrestler Kevin Thorne was referred to simply as "The Vampire", and had a couple of matches without any ring introduction that might give away a name, before his name was finally revealed. This may be because the writers simply hadn't figured out what to call him...or because "Kevin" is a really stupid name for a vampire, even if Thorne is a good one.
Same with Hornswoggle. When Fit Finlay's leprechaun companion and son was first introduced in 2006, he did not have a name - but Michael Cole took to shouting "Look! It's that little bastard!" whenever he'd show up, so the nickname "Little Bastard" stuck. Nearly a year would pass before Finlay finally revealed that the leprechaun's "real" name was Hornswoggle.
The name of The God-Emperor of Mankind from Warhammer 40,000 has never been revealed. He is always referred to as the Emperor. Ostensibly, The God-Emperor is a transcendent being who has had tens of thousands of lives (although Sigmar's origin story is very similar to the post-Age of Strife God-Emperor). His backstory is given as being the final reincarnation of thousands of amalgamated shamans 48,000 years before the main storyline: which would give him an innumerable quantity of possible names — and no need for any of them.
It's heavily implied he was a lot of important historical figures, including Jesus.
There is also the Scarlet Empress in Exalted, and both the Death Lords and the Abyssals are reqired to go by title and not name.
For Dungeons & Dragons we have the Lady of Pain and the Raven Queen (Goddess of Death). Some demons try to learn the Raven Queen's true name to depose her of her power and attain godhood.
The Red Knight is the Forgotten Realms demigoddess of tactics and strategy. Only her superior Tempus knows her real name. Faiths & Pantheons states that if anyone else were to learn it, that person would be privy to all the plans and intrigues of everyone in the entire universe.
One of the named (such as it is) characters in the Anima Tactics game is The Colonel, a man implied to be feared over and above others even in his own kingdom (that is made up of badasses and demons). In his description, it is stated that the number of people who know his actual name can be counted on one hand.
The Naga in Legend of the Five Rings use this trope in similar way to the Qunari: Their titles are their names. Their telepathy keeps it from getting confusing when a Naga's rank or job changes.
In a somewhat meta example, Puck from A Midsummer Night's Dream. His name is technically Robin Goodfellow (taken from folklore), but he's referred to as "Puck" several times by Oberon and in many of the speech prefixes. Scripts of the time commonly used descriptive terms instead of names in the speech prefixes, so Puck is not necessarily his name, any more than, say, Feste's name is "Clown", or Shylock's name is "Jew". "Puck" was a word more in line with "pooka", or "sprite". So Puck is what he is, and Robin is his name. The one time he refers to himself as Puck is when he says, "As I am an honest Puck..."
Wallace Shawn's The Hotel Play had over 20 characters, all identified with names like "The Girl Who Broke the Bowl", "The Man Who Looks Like a Walrus", "The Hotel Clerk".
Many characters in The Drowsy Chaperone: The title character, The Man in Chair, the Gangsters, and Underling. And these are all main characters!
In the musical The Phantom of the Opera, the title character (who also goes as "Opera Ghost") is never called "Erik" or by any other proper name.
The Mayor in the Latibćr plays is just called "Bćjarstjórinn" which means "The Mayor", "the" and all.
The Arbiter from Chess has had a few names over the years — Constantine Stannos (Broadway), Jean Jacques Van Boren (Swedish), Kobe Obe (US tour). Most adaptations only refer to the character as "The Arbiter", and the ones that name him generally just call him by his title.
Many characters in Into the Woods, such as the Baker, the Witch, and the Mysterious Old Man.
This applies to just about everyone in Intothe Woods besides Cinderella, Jack, Florinda, Lucinda, and Milky-White.
In Pippin, the leader of the troupe of players is identified only as "The Leading Player"
In Agnes de Mille's ballet Rodeo, all of the named characters share this trait: the Cowgirl, the Rancher's Daughter, the Head Wrangler, and the Champion Roper.
De Mille did the same thing in Fall River Legend (the Accused, the Pastor, the Speaker for the Jury, etc.).
Rock Raiders: The captain of the LMS Explorer is only ever referred to as "Chief".
In Postal, the Dude's wife is just called "[The] Bitch". Nothing else.
Final Fantasy X-2 This trope's name is based on the character Barkeep. Characters refer to this Hypello crewmember as Barkeep because they inexplicably don't know his real name. He doesn't even know his real name.
The game includes a minor NPC named Mankrik who tasks you with finding his wife, who he fears has been killed. Sadly, he's right. Her body, when you find it, is named "Beaten Corpse".note Fanon Choose Your Own Adventure Parody Fanfiction You Awaken in Razor Hill finally gave her a name, over five years later. Marya, or Mary for short.
Players in World of Warcraft frequently fall victim to this too, when in pickup groups. "Tank, are you there?" "Rogue, do this and that."
For some time, there was a human NPC named Captain Placeholder running around. Sadly, he was later replaced by sombody with an actual name.
In the Halo series, the Arbiter's true name is never mentioned, while the Master Chief is referred to only by his rank (or occasionally his designation number "117") until the very end of Halo 3. However, the books reveal that their true names are respectively Thel 'Vadam(ee) and John.
Most pre-4 Covenant characters are never addressed by their names in-game; the names of the Prophets of Truth, Mercy, and Regret, the half-jawed Shipmaster, and the Halo Wars Arbiter have only been revealed in non-game material. note In case you're wondering, they're Ord Casto, Hod Rumnt, Lod Mron, Rtas 'Vadum(ee), and Ripa 'Moramee.
The Expanded Universe reveals that many high-ranking Forerunners were referred to only by their titles; the two main examples would be the Librarian and the Didact, who called each other as such even though they were married.
Likewise, the bellboy in the first game is always referred to as "the bellboy" or "that creepy bellboy."
Wing Commander: In addition to most pilots usually being referred to by their callsign only, the first game had a bartender named "Shotglass" (his callsign from his pilot days) and the second and fourth games had mechanics named "Sparks" and "Pliers" respectively.
The latter was lampshaded in the novelization when Blair, initially unsure if he was hearing a nickname or an actual if unlikely name, has to ask if they really had a mechanic named Pliers.
In Crusader the Silencer is usually just referred to as "Captain" (his rank) or "Silencer" (his old unit). A few people give him nicknames ("Tin Man", "Red", etc.), but they aren't used more than a couple times.
The Doomguy in Doom 3 is only ever called "Marine".
Or Doomguy by the fans.
In both the novel adaptation (Which eventually drifted towards World of Weirdness territory) and the movie he has a name (Flynn "Fly" Taggart and John "Reaper" Grimm respectively).
Played as straight as can be in Stalker - Shadow of Chernobyl, in which a well-known trader and owner of a local bar is known only as "Barkeep".
The Legend of Zelda has the Postman as a character in several of the games. Both Nintendo 64 games also feature the Happy Mask Salesman
The G-Man from Half Life 1. In fact, "gman" was just the name of his character model. Nobody in the game calls him anything, except for Eli Vance, who refers to him as "our mutual friend". In the manual for the Opposing Force expansion, however, Shepard writes about a G-Man watching him during his training and, indeed he can be seen during the tutorial mission. And he is listed as "GMan" (no hyphen) in the credits for Half-Life 2 and its Episodes.
"Wait, the Pub Barkeep's name is actually Pub Barkeep?"
The player character of Knights of the Old Republic II is commonly referred to (in-universe and out) as the Jedi Exile. Atris's handmaidens all apparently go by Handmaiden, including the one who joins the party if the Exile's male (her real name, revealed late in the game, is Brianna). Her counterpart character for a female exile, whom you meet in the Jedi ruins of Dantooine, is known as "Disciple" (his real name is Mical).
There's an interesting case with Mandalore, who is referred to by name only once in the whole game; Mandalore is his title. He spent the whole of the previous game being referred to by his name Canderous.
Star Wars: The Old Republic actually has a few cases of this in its own right. Each one of the classes picks up an appropriate nickname. The Imperial Agent, for example, is given the code name "Cipher 9." The Bounty Hunter is simply called "Hunter" (in the case of a male Hunter, Mako will sometimes call you "Big guy"). A couple of the party members also fall into this. Jedi Knight companion Doc prefers being called that to his Embarrassing First Name, and Consulars get the terrorist turned politician who goes only by "Zenith."
Despite being the title character, Iji's brother is the only one to call her by her real name. All the aliens call her "(the Human) Anomaly" (even the friendly ones!)
Except Ansaksie in a pacifistic run, right before Iji confronts Tor.
Vyers from Disgaea is never called anything other than Mid-Boss by the other characters, to his great frustration. Any attempts to bring up his name are usually shot down before he can even say it.
Straighter examples of this trope are all over Disgaea 2. Immediately obvious are Mom and Dad, but only slightly less noticeable are the Director and Cameraman who follow Axel around. And don't even get us started on "Fake Zenon". According to the Disgaea 2 art book, their names really are Mom and Dad.
Disgaea 3 also features a character only known as the School Board President.
In the Fallout series you have always been allowed to name your player character, but how you are referred to by other characters has been different from game to game. In the first two games this trope is mostly averted since the majority of the dialogue is in text only, and as such you are frequently referred to by your given name. In any of the voiced dialogues, they typically avoided referring to you directly or occasionally by some sort of title (like "Initiate" by the leaders of the Brotherhood Of Steel in Fallout and "Chosen One" by the people of your home village in Fallout 2). From Tactics and onwards however, all dialogue became fully voiced and this trope came into full effect. In all the later games your character (and retroactively, the protagonists of the first two games as well) is referred to only by a title: "Vault Dweller", "Chosen One", "Warrior", "Lone Wanderer" and "Courier". This is an Acceptable Break from Reality so the radio shows can refer to you by name.
"The Lone Wanderer" apparently is Three-Dog's Fan Nickname for the protagonist that ended up becoming an in-universe Ascended Meme, since his original description of them as "That Kid from Vault 101" sounded terrible on radio.
In New Vegas, the protagonist can introduce themselves simply as "The Courier", due to the fact that most people have heard of your miraculously survival from being shot in the head and buried alive and that to be in your chosen profession, you are badass enough to walk across post-apocalyptic wastelands for a living. As Cass so eloquently puts it;
Cass: Rule of the Caravan Wastes: Don't fuck with the guy who delivers your mail!
Happens to three characters in Dissidia: Final Fantasy. The Onion Knight from Final Fantasy III is only referred to by his title with no indication of what his real name is (in accordance with the fact that the Warriors of Light from FFIII - not to be confused with the Warriors of Light from the original Final Fantasy - weren't assigned names until the DS remake). His title is also rarely used by characters in the game, except for the voiceover intro at the start of the chapter — he is generally just referred to as "the kid". The Emperor of Final Fantasy II does have a name, Mateus, but it is only used for his final weapon and never in the dialogue. The Warrior of Light also has a name but in accordance with the story of Final Fantasy I he has amnesia and cannot remember it. Cloud of Darkness, also from Final Fantasy III, seems to invoke this trope, but although it appears as a humanoid female, the Cloud is not really human, and the name is a simple description of the entity — it doesn't actually have any other name.
The Space Pirates in the Metroid series refer to the heroine as The Hunter. When her Evil Twin shows up, they logically name it The Dark Hunter. The benevolent characters use her real name, though. The Chozo sometimes refer to Samus as Hatchling or Newborn.
The merchant in Resident Evil 4. Inversely, the merchant refuses to know Leon's name, only referring to him as "stranger" — or strain-jah if you will.
This continues into the sequel (Chain of Memories, not Kingdom Hearts II), with Journal entries for him and his Friend Card only using "The King". At the end of Riku's half of the game, Mickey tells him he can drop the pretenses, whereupon Riku uses the king's name.
Team Fortress 2: Everyone Calls Them Scout, Heavy, Engineer, Sniper, Spy, Soldier, Demoman, Medic and Pyro respectively, leading to Fan Nicknames such as "Engie" or "Solly".
However, the comic that introduced the WAR! update revealed that the Demoman's name is Tavish DeGroot and the Announcer's name is Helen. The Loose Canon comic reveal the Engineer's name to be Dell Conagher and Meet the Director revealed the Sniper's last name to be Mundy. However, the WAR! comic also indicates Soldier has No Name Given because he's referred to as "Jane Doe", indicating even his employers don't know his name, and one item describes him as "a nameless man".
The Doctor in Harvest Moon: Friends of Mineral Town/More Friends of Mineral Town is just called "doctor," no matter what. Even if you marry him, he continues to go by just "Doctor." (However, in Harvest Moon DS, he gains the name "Trent.")
The Witch and Wizard in Animal Parade are referred to as just that by most of the town, though they'll reveal their actual names when married — Vivi and Gale, respectively. The Harvest Goddess and King turn out to have proper names as well under the same condition. Theirs are Sephia and Ignis.
Cross between Truth in Television and Video Games; this often happens in online adventure games like World of Warcraft... "OK, the rogue will sap that one, the mage will sheep this one, and the tank (not even the class name) will hold the other two."
The ball of stone that everything lives on is Chiron. The entity formed of the miles and miles of xenofungus that covers Chiron named itself Planet, when it first learned to speak to humans, before it had a good understanding of English.
The xenofungus entity is named Planet. The ball of rock is also called Planet (though it is named Chiron) — eg. University of Planet, "Planet's atmosphere", "Planet's industry", "Planet's primary"...
Said supplementary materials when talking about Chiron at one point says, parahrased, "the proper name of the planet the Unity crew arrived on is Chiron, but everyone calls it Planet".
The Qunari in general use ranks as names, at least to other races. Some of these are obvious, like "the" before Arishok, implying it's a leadership title. Saarebas ("dangerous thing") is a word/rank/name for a mage, which are treated a thousand times worse than human mages (their mouths are sewn shut, and the must wear chains and collars).
If the Player Character is from the Human Noble or Dwarf Noble Origins, they are occasionally addressed as Lord/Lady Cousland/Aeducan, respectively, but the rest of the time they are simply called "the Warden". If they hail from any other origin, they are the Grey Warden, period. Which is a bit strange considering your character has a set, unchangeable last name regardless of which origin you pick. Chances are you forget what it was before getting through the prologue, seeing how it is hardly mentioned anywhere again after the character creation screen (unless you made a noble, as pointed out). Even stranger, Alistair is always an available party member for at least three-quarters of the game, and is a (slightly) more senior Grey Warden than the player character, yet it is the PC who is always addressed as "Warden".
Sten isn't the resident qunari party member's real name, but a rank, as his real name cannot be pronounced by a non-qunari.
In Dragon Age: Origins – Awakening, it's likely that most of your party will go through the Joining, becoming Grey Wardens, so the PC is now known as "Warden-Commander" or simply "Commander" to distinguish them from everyone else. This trope gets a bit of a lampshade as a result:
Ohgren: You. Hey, you! Warden: That's "Commander Hey You", by the way.
In Dragon Age II, this trope is probably why the new Player Character now has a static last name, allowing everyone to simply call you Hawke. Conveniently, your siblings, mother, and uncle will use every pronoun and substitute word imaginable to avoid saying your first name (which you can pick), as it wouldn't make sense for them to call you Hawke. However, the Chantry lady in the Frame Story does constistently call you the "Champion of Kirkwall". With most Origins import options, the Warden from the first game will be referred to as "The Hero of Ferelden" by most NPCs in Dragon Age II.
The Illusive Man from the Mass Effect series is a one man Omniscient Council Of Vagueness. Nobody knows who he is, where he came from, where he is currently located, and what he actually wants. The only thing that can be said about him for sure is that he looks like a human male about 60 years of age and apparently has almost unlimited resources at his disposal. He does get an origin story in the comic mini-series Mass Effect: Evolution, which reveals, among other things, that his name is Jack Harper.
Neverwinter Nights referred to the player by name in the text of conversations, but the voiceovers just say "You".
Neverwinter Nights 2 has your party calling you "our leader" and "our fearless leader" at various points. When you get promoted, it becomes "Captain" or "Knight-Captain" in most cases.
The real name of the King of Shadows (as in, the name he had when he was a human) has been lost to the ages. Even the ghosts in the Illefarn ruins don't remember it.
The assassins in the first No More Heroes mostly go by codenames (with the exceptions of Rank 6 and, as clarified in the sequel, Rank 5). Their character cards give the real names of all but the last three. The sequel averts this, as every assassin uses his or her real name save New Destroyman and possibly Rank 9.
Wait, what about Harvey Moiseiwitsch Volodarskii? Isn't that his real name?
The protagonist in Fable I and Fable II. You can choose his(/her) title but most of them are exactly like this trope. All other characters have actual names, then again, although there is also The Guildmaster and The Archeologist.
The expansion pack reveals that the Guildmaster's true name is Weaver.
The Silent Protagonist in Freespace 2 is always Alpha 1, or occasionally "pilot", at least as far as all the other characters are concerned.
Chzo Mythos: Trilby. A trilby is a type of hat and the character is always wearing one, the other characters are never told Trilby's actually name, but Word Of God says that his first name is Malcolm.
The Commander in Dawn of War II is only referred to as such by his fellow Space Marines. His Canon Name, according to the novel, is apparently Aramus.
The player characters of Assassin's Creed: Brotherhood multiplayer seemed to have this at first. There's the Priest, Courtesan, Hunter, Doctor etc. Then the beta revealed that they do have names after all.
The Monkey Island series has the Voodoo Lady, the proprietor of the various Voodoo shops seen throughout the series, from the International House of Mojo to Voodoo 'n Things (formerly just Voodoo), and Guybrush's primary source of advice throughout the series (with a five-game contract from LucasArts). She insists that while her real name isn't important, names have power over people, and refuses to share hers.
The Masters of the Bazaar in Fallen London are known only by appellations related to their primary trade goods — Mr. Wines, Mr. Stones, Mr. Iron, etc. Nearly every other character you encounter has a similar non-name: the Repentant Forger, the Comtessa, the Revolutionary Firebrand, and so forth.
F.E.A.R. loved this trope in the first "generation". The Point Man is only really addressed by Betters, as "Buddy" when called directly, and "my man" or "my point man" when he's talking to others about him. The Sergeant from Perseus Mandate fits squarely into this trope, being called exactly that by his squadmates Chen and Raynes. Nobody else even gets close to saying a vocative to them.
Embric of Wulfhammer's Castle has both the Duchess of Elstwhere and the Good Dwarf. While the former does have a name it is only mentioned in a handful of the Multiple Endings, otherwise referred to only as Duchess, and the latter also has a name (or names, rather) but no-one could understand him, so they compromised.
An odd example in Mega Man Legends. The main character is Mega Man Volnutt, but everyone calls him Mega Man. Later in the game, you encounter other Mega Men, with the implication that "Mega Man" is more of a title than a name.
The protagonist in the Mystery Case Files series is referred to as "Detective" or "Master Detective", even when Cassandra Williams leaves her a voicemail at the beginning of Shadow Lake. Apparently the Master Detective paid extra to get her phonebook listing under her nickname.
Played with a couple times in Escape from Ravenhearst, when the game inserts the name you used for your current profile — a gravestone and a note to you from Charles will both have your profile name.
The voiced dialogue in both Persona 3 and Persona 4 only refer to the protagonists as "Leader", "Partner", or "Senpai". Persona 3's MC is named "Minato Arisato" in the manga and "Makoto Yuuki" in the movie, and Persona 4's MC is "Souji Seta" in the manga and "Yu Narukami" in the anime.
In Citizens Of Earth, this applies to every character. The baker, the conspiracy guy, Mom, the cop, etc. You can rename them, though.
In The Elder Scrolls V: Skyrim, your character usually get called "the Dragonborn" or "Dovahkiin", regardless of the name you gave to yourself. You can get other designations by joining various Guild (Hardbringer, Legate, Listener...), but you will never be referred to by your name.
In Valkyrie Profile, mortals refer to Lenneth simply as "the Valkyrie". This is played with to great effect in Valkyrie Profile Silmeria when the fact that Rufus knows the given names of all three Valkyries is the first big hint that he's more than he seems.
In Fate/stay night, the Servants are called by their character classes to disguise their true identities (and thus, their legendary weapons, abilities, and (most importantly) weaknesses) from their opponents. Unless the Servant is too arrogant to worry about such things, as in the cases of Gilgamesh and the Fate Zero Rider, Iskander.
Scary Go Round has a character named "The Boy" (only recently named as 'Eustace Boyce'). His parents are eventually revealed to be named "The Father" and "The Mother", naturally. There is also an enigmatic character who has not properly been introduced to any of the cast or the public, whom the media have dubbed "The Child". One of the main characters remarks to The Boy that it's suspiciously similar to his name.
Near the end of Scary Go Round, The Child was revealed to be named Poh.
In 8-Bit Theater, the main cast's ACTUAL NAMES are Fighter, Thief, Red Mage, Black Mage, White Mage and Black Belt.
The eventually-revealed surnames aren't any better: Fighter McWarrior and Black Mage Evilwizardington are given, and the author has apparently decided on Red Mage's being Statscowski. As for Thief, his other name is Prince Elf of clan Khee'bler.
They also technically subvert it by going through a class change and not changing their names to Blue Mage, Mime, Knight, and Ninja.
Secondary characters also face this like Dragoon, Onion Kid (an in-series newspaper suggested his named was "Rex Crockett", but Word Of God suggested that's not really his name), Archer, or The Other Warriors: Cleric, Rogue, Berserker Axinhead, and last but not least Generic Half-Elven Dual-Class Rangernote The second class was also Ranger.. Later on we learn that the onion kid's true name is Sarda.
The main villain of ConScrew has somehow kept the rest of the main cast from learning her real name, so they all just refer to her as 'Fangirl' after her always using 'Rabid Fangirl' as the name on her Con IDs.
Jayden and Crusader's character Third officially has no name. He is called Third because he was the Third Character. No one seems to think this is odd...
Perhaps a more fitting example of this trope is Cinema Guy, of the same webcomic. His real name has been revealed to be Kevin, but everyone calls him Cinema Guy much to his annoyance.
All the Deaths in Irregular Webcomic! are refered to by what they are the death of ("Death of Insanely Overpowered Fireballs" is usually called that, although it's been shortened to just "Fireballs"). If they're assigned to be the death of something else, the Death's name changes, too.
Van Von Hunter has an unnamed sidekick. She suffers from overlapping cases of amnesia and can never remember what her name is, so everyone calls her "Van's sidekick/associate/partner/whatever" or just don't call her anything.
The bartender in Corner Alley 13 is just called bartender. The supplemental material even acknowledges it:
His real name is unknown, which kind of shows what his friends are worth.
The Exiles: Wayward Vagabond, Peregrine Mendicant, Aimless Renegade and Windswept Questant. They are more commonly referred to using their initials (WV, PM, AR, WQ) both in and out of the comic. The Exiles collect potential meanings for these initials throughout the story: WV is also Warweary Villein, Wizardly Vassal and Wastelandic Vindicator; PM — Parcel Mistress, Prospitian Monarch; AR — Authority Regulator, Armaments Regent; WQ — White Queen.
The Guardians: John's Dad and Nanna, Rose's Mom, Dave's Bro, Jade's Grandpa. The only one with an actual name is Becquerel, and he's a near-omnipotent dog.
Well sort of. In the B2Universe the new SBURB players are named: Nanna is Jane, Rose's Mom is Roxy, Dave's Bro is Dirk, and Jade's Grandpa is Jake. John's/Jane's Dad is still just Dad in this universe though.
The troll's ancestors: only Redglare, Mindfang, Darkleer and Dualscar are given names; the Handmaid, the Summoner, the Helmsman, the Disciple, the Dolorosa, the Grand Highblood and the Condesce are all known by their titles. Then the Sufferer sort of has a name, Signless, but it's not used as often and isn't his original name (if he had one).
Like the Universe B Guardians, the Ancestors are named when we meet their alternate versions in Act 6.
Almost everyone in The Whiteboard is known only by a nickname; "Doc", "Rainman", "Bandit", etc. The few characters with a "real" name don't have a last name; Jake, Sandy, Pirta, Gino, etc.
An initially nameless character in Bittersweet Candy Bowl was dubbed "Final Fantasy Cat" by fans. Although Word Of God has since declared his name to be Augustus, the author still frequently refers to him as Final Fantasy Cat.
The kobold oracle of Tiamat in The Order of the Stick is only know as "The Oracle of Sunken Valley", or the Oracle for short.
Played in the straightest way possible in The Pigs Ear; the barkeep of the titular pub is, indeed, solely addressed as "Barkeep". It may well be his real name.
Meta-example: Other than the title character and a handful of others no one inminushas a name. Outside the comic, characters have to be referred to by one of their aspects, such as "the green-haired girl".
Hero's team members n Lord Of The Ring The Third Age don't call each other by names but races and occupations, which is strange, since ever character's names are fixed and they shouldn't had any problem with dubbing.
Mistress in Oglaf. No one calls her by name. No one seems to know her name, and, frankly, no one would be brave enough to ask.
The Captain assigned to the central mystery in Kaspall.
The french-speaking MP3 series Le Donjon de Naheulbeuk (The Dungeon of Naheulbeuk) never gave the names of its main protagonists, even when it got adapted into comics or novels. Being typical parodies of standard RPG playable characters, they're only identified by their race or class (the Ranger, the Dwarf, the Elf, the Barbarian...).
Red vs. Blue has a medic introduced with the name DuFresne. It's decided by the other characters that his name is too hard to pronounce and he is christened "Doc" for the remainder of the series.
The Red Team Sergeant is an example for most of the series, known only as Sarge, however it is eventually revealed his name is actually Sarge.
Sister is another example. Her real name is stated by the DVD profiles to be Kaikaina (which is Hawaiian for "younger sibling of the same sex", which counts as a Stealth Insult to Grif), but all characters, including her older brother, only ever call her Sister.
The Freelancers have The Director (whose name is eventually revealed to be Leonard Church, but he's still rarely ever called by it), and The Counselor (whose name has yet to be revealed).
VIC is a final example; while "Vic" is a real name, it actually stands for Virtual Intelligence Computer. Similarly, though FILSS is often referred to as "Sheila", her real name stands for Freelancer Integrated Logistics and Security System. In both cases, their "names" are more descriptors of what they do than a unique name.
The private detective in the 3D Movie Maker film-noir parody Pamela has the first name "Detective", giving him the name plus title of Detective Detective Joe Peterson. (So when another character calls him "Detective", he thinks she's on a first name basis with him.)
The LoadingReadyRun sketch "Johny Four" had the titular Johny tell the story of how he went to the local bar called Bar where he ordered a Beer brand beer which was served to him by a bartender called Bartender. Johnny is an Unreliable Narrator so we are not sure if that is the guy's real name or just the name he uses at work to fit the bar's theme.
Beauty and the Beast: The Beast is only ever called well, "the Beast" ("the" optional), except for his servants, who call him "the Master".
The Brave Little Toaster: Except for Kirby (who is a vacuum cleaner), all of the characters are named after what they are, and the owner of the objects is only known as "The Master". "Kirby" is actually the name of a brand of vacuum cleaner, however, so this trope still applies.
Cow and Chicken features this trope, most commonly with the parents being known as 'Mom' and 'Dad.' Perhaps the most blaring example is when we see Cow and Chicken's school-teacher at her home, where the mailbox is marked 'Teacher.'
The Simpsons: Notably, Comic Book Guy and Sea Captain, both of whom have real names that are rarely used (Jeff Albertson and Horatio McAllister, respectively); the latter had a name (Captain Alastor) before gaining the more popular nickname. There are also a number of other examples who show up less frequently, including the Squeaky Voiced Teen, Bumblebee Man, Blue Haired Lawyer et cetera.
One of Springfield's tourist attractions is Carl's Dad Caverns, with a sign stated they've been discovered by "Carl's Dad". Lenny's grandmother has a tombstone labeled "Lenny's Grandma".
The Critic: The kid's name is actually "Pizzaface" on his name tag at some point.
That's "Pizza FAH-Chay"
South Park: Chef, although a throwaway line in "Chef Aid" revealed his full name: Jerome "Chef" McElroy.
Gerald once referred to himself as "Kyle's Dad" in a commercial advertising his lawyer services. While not completely fitting the trope because the other adults still call him Gerald, the joke was still used with the same intent.
Family Guy: Evil Monkey, Greased Up Deaf Guy, etc., etc.
Hey Arnold! has several examples: Chocolate Boy (chocolate addict, who's still referred to as such without object even after he stops eating chocolate), and Peapod Kid (appeared in a peapod costume in the first episode), Stoop Kid (guy who sits on his stoop at all times).
Stoop Kid is a description/title, as Arnold and friends don't actually know him (at least at the beginning).
Recess does this a lot, with most of the kids outside the main gang known by descriptions such as "Swinger Girl" or "The Diggers". In one episode it was revealed that, to kids other than her close friends, TJ was "Crazy Monkey Boy", Gretchen was "Smart Girl", Mikey was "Large Thoughtful Boy", Vince was "Kid Who Always Wins", Gus was "Friend Of Smart Girl", and Spinelli was "Girl Who Runs With Fists".
The Eager Young Space Cadet in Duck Dodgers. Though his name is probably "Porky Pig".
The Fat Controller in Thomas the Tank Engine is hardly ever referred to by his real name (Sir Topham Hatt) in the original (British) version of the series, although he is always called Sir Topham Hatt in the North American version.
Judge Hiram Mightor: State your first name, last name, and occupation. Lizardman: Lizardman, Lizardman, and uh... Lizardman.
Though immediately after his testimony, the other Lizardmen in the courtroom call him "Bill".
The Earth King of Avatar The Last Airbender is never called anything other then "The Earth King". According to Nickelodeon site he was born "Kuei", but was never referred as anything other than his title after being crowned at age four, which apparently was the same with all of the other kings. If a previous monarch needs to be mentioned specifically, they're simply referred to by number.
Avatar actually does this for quite a few people; Longshot, The Foamy Mouth Guy, Sparky Sparky Boom Man note which, thankfully, was quickly changed to the much cooler-sounding Combustion Man, The Cabbage Guy, The Mechanist.
For that matter, the spirit the Avatar is the host for has never been called anything but "The Avatar Spirit" even though all the other spirits have names. As it's been described as the spirit of the planet itself, a name wouldn't exactly be necessary.
From the Looney Tunes short "Deduce, You Say", a Daffy Duck/Porky Pig cartoon parodying Sherlock Holmes:
Experiment 625 from Lilo & Stitch: The Series was never given a "true name" until the very end of the series, when Lilo finally "caught" him and then helped him decide on a name. They chose Reubennote "the classic corned beef and sauerkraut on rye" , because he's good at making sandwiches.
On Jackie Chan Adventures, nobody knows what Uncle's real name is. Or, for that matter, whose uncle he is. For example, Jade's father believes Uncle to be his cousin and he's not sure of it either.
This notably extends outside of the family, too. EVERYONE calls him Uncle.
Dungeons & Dragons has Dungeon Master and Shadow Demon. For that matter, Dungeon Master almost always addresses the heroes by the titles he gave them, rather than their names: "Fear not, Ranger! Barbarian! Magician! Thief! Cavalier! And Acrobat!"
In Jane and the Dragon we have Jester and Smithy. And Pepper and Rake are only known by nicknames related to their occupations (which are cook and gardener respectively).
The Berenstain Bears: Brother, Mama, Papa, and Sister. Both family and friends refer to them as such, which — if you consider the fact that Mama and Papa are husband and wife — makes things decidedly Oedipal.
Many parents will refer to each other as "Mom" and "Dad" especially in front of the kids. When everyone from your kid's teacher to the man at the grocery store does it, however...
In Disney's Aladdin, Aladdin's genie is known only as Genie, or sometimes The Genie. In the sequels and series this becomes particularly strange, as Jafar is also a genie and another named genie is introduced.
One episode also features a character that's only known as Wazir. It makes more sense than the genie example, as the king he works for is not only a child king, but moody and egocentric, i.e. not the type to be bothered with learning his wazir's name.
The Big Bad Duumvirate of Invader Zim are referred to exclusively in the show as The Almighty Tallests, or The Tallests for short. Their names (Red and Purple) are only shown in the script.
Snack Shack from Stoked, nicknamed after where he works.
The Venture Bros. has a few in the Pirate Captain, the Monarch henchmen (except for #21,) the Alchemist (who is sometimes just called "Al," it is unknown if that is just short for the Alchemist or his real name,) Orpheus' Master is just referred to as "Master," and the Outrider.
The two main characters of 2StupidDogs, neither of which is named on the show. They are simply referred to as Big Dog and Little Dog by fans.
In many families, people are expected to always refer to their parents as "mom" and "dad" or similar nicknames. Referring to your parents by name may be seen as disrespectful. Stepparents are often referred to by their first names, especially if the children knew them for a while before marrying their parent. In-laws can be another exception, and it can be uncomfortable deciding when and if one should make the transition into referring to them as mom and dad.
Many common surnames refer to the trade of the original person, such as Smith, Miller, Baker and so forth. Many other languages have equivalents.
In the Wild West, people tended to be known by nicknames, often referring to their occupation. Just ask Doc Holliday — he was a dentist as well as a gunfighter.
Once a historical figure becomes a legendary figure, sometimes within their own lifetime, they often end up going by a title. Some examples are Augustus Caesar, The Buddha, Christ, Mahatma Gandhi, Genghis Khan, and any Chinese philosopher whose name ends in "Tzu".
Some figures' real names in the Biblical tales have never been recorded and their very existence is shady at best, so people know them only by a moniker: the Roman soldier who pierced Christ on the Cross is just "Longinus" ("the lancer"), while "Veronica" meant just "true image".
Julius Caesar's given name was actually Gaius. Julius was the name of his noble family and Caesar was the branch of the family. But due to Roman naming conventions, he, his successor, and the fourth man in his dynasty were all named "Gaius Julius Caesar" at some point in their lives. They became known to history as Julius Caesar, Augustusnote a title meaning "majestic", and Caligulanote a childhood nickname meaning "little soldier's boot".
Quite a few Middle Eastern historical figures are prone to this. Generally such-and-such "al-Din" would be a title or name adopted or given to a person later, as it refers to "the Faith," and people would take on such names as a result of exceptional piety or success at defending Islam. The Crusades tended to produce people known as things like Nur al-Din and Salah al-Din, neither of whom were born with those names.
El Cid. Who remembers his real name, Ruy Diaz de Vivar?
Subverted with the Sun and the Moon. Every other moon in our solar system is given a name, but the Earth's moon is just called the Moon, and our solar system's sun is simply called the Sun. (somewhat unofficial names for them are "Luna" and "Sol")
The President of the United States is addressed as Mr./Madam President.
They are also allowed to be called "President [Surname]" even after their tenure in office has ended.
In most armed forces, it is standard for lower ranks to address their superiors by their rank, or occasionally by their function. Calling a superior by their surname, e.g. "Sergeant Smith" may net the answer "I know my own name". Unless, that is, you are addressing a group of sergeants, in which case just calling, "Sergeant" will get you a pack of "What kind of idiot are you?" looks because you weren't specific.
The rank of Lieutenant in the American military can net the "nickname" El-Tee (LT), the rank's abbreviation. No other officer rank lends itself such.
In certain contexts, you might be less concerned about addressing one person in particular, and more about finding a certain type of person. Hence, calling for MEDIC when someone is wounded in battle or during training.
Dukes and earls in the UK commonly refer to each other by their title. For example, the Earl of Warwick would be simply addressed by his peers as "Warwick".
Although he is not the only individual to hold that title, if you refer to Lord Byron (whose name was George Gordon), people generally know which one you're talking about. The same goes for the Marquis de Sade (Donatien Alphonse François).