On many reality shows (one example being Billy the Exterminator), last names aren't given, even the ones of the people the show is about.
The BBC made a documentary about the research centre Porton Down, which is one of the most secret sites in Britain. The site director was the only person interviewed whose surname was shown, and it is possible that "Alan", "Marcus" and "Cerys" were not those people's real names.
The 4400: In the two-part story "Gone", the real name of the woman from the future who posed as Maia's sister Sarah Rutledge is never stated.
All but one of the cast members in According to Jim are only referred to by their first names. The one exception takes place in Dana after she gets married and adopts her husband's surname.
GOB's wife on Arrested Development is never given a name, to reflect the fact that GOB doesn't know it. She's listed as "Bride of GOB" in the credits and "Wife of GOB" in other material. GOB makes several guesses to it, including "Krindy", "Amy" (Amy Poehler, Will Arnett's wife, plays the role), and "Saul" (actually her divorce lawyer). Michael knows what it is, but the opportunity never arises for him to use it.
From Becker, Linda and Bob's last names were never revealed.
If you're trying to remember the full names of all the characters on The Big Bang Theory, you might find yourself stuck when you get to Penny. We have six characters with fun-sounding three-word names, and then just... Penny. Heck, since her real name being "Penelope" was only implied, we can't even say for sure we know her first name.
Bones has never revealed the name of Angela's father. Or her real name for that matter. We know her dad is Billy Gibbons in real life, but he never is given an onscreen name. And Angela named herself when she became an adult, due to her dad giving her an Embarrassing First Name.
On Angel, "The Host of Caritas" was not given an official name (even to the other characters) until late into the second season. His full name is "Krevlornswath of the Deathwok Clan". As noted before, he's not fond of it:
Host (who is a green-skinned demon): It's Lorne. I don't like to mention it because, well... Angel: Lorne Greene! (Cordelia and Gunn stare blankly) Angel: Bonanza? Fourteen years on the air doesn't mean anything? (They are still blank) Angel: Okay, now I feel old.
One might wonder why he didn't shorten it to Krev instead of Lorne, so that he could say it's short for Crèvecur (heartbreaker). Okay, maybe that's too recherché.
Darla's human name is not known - she was named Darla by the Master, and being a whore, she probably wouldn't have used it anyway. We learn this when she is revived as human; by this time she does not remember having a name before "Darla". By the time she sired Angel she had been Darla for over a century, and in over a century with him she never mentioned her original name.
It's a while before we find out Angel's real name is "Liam".
Faith's surname was not revealed as Lehane (probably a Shout-Out to the crime writer Dennis Lehane) until after the TV shows ended. It was first used in the support material for the official role-playing game. The lack of a surname subtextually places her among the show's supernatural entities and villains, most of whom have Only One Name.
While we know that Spike's real name is "William", only after the shows ended did Joss Whedon reveal his last name is "Pratt".
Glory is introduced as something that predates language, and thus has no name. Indeed, the name "Glory" is a moniker shortened from "Glorificus", which is just Medieval Latin for "glorious" - how her worshipers refer to her.
The dancing demon in "Once More With Feeling" is never named in dialogue, though he is known to fans as "Sweet" because of a credit for "Sweet makeup". This violates the typical formula for a Buffy episode: Weird Stuff Happens/People Die/stuff gets stolen → the gang researches → they learn the threat's name and weaknesses → they vanquish said threat. But in this episode Sweet simply leaves without actually engaging in violence (aside from people bursting into flames).
The human members of the Circle of the Black Thorn are unnamed.
The BBC show Bugs manages this with the three stars, Nick Beckett, Ros Henderson and 'Ed', who has no specified surname.
On Chuck, Sarah's real full name is unknown as of yet. Her other known childhood aliases are Jenny Burton, Rebecca Franco, and Katie O'Connell. As Bryce Larkin's partner, she was known as Mrs. Anderson on some missions. She introduces her father as Jack Burton; it's likely that was just the first name she thought of, since Chuck knew the Burton alias but not that it was an alias, and Jack was willing to play along. She does tell Chuck her middle name is Lisa, and from context it's likely that much is true.
In "Chuck Versus the Fake Name", Sarah's real name is found out: Sam.
Colonel Casey's real name was also not known for some time, but eventually revealed to be Alexander Coburn.
Sarah is more of a case "No Original Name Given", since in "Chuck Versus the Family Volkoff" we learn that "Sarah Walker" is indeed her legal name and probably the one she's had the longest, which makes it as good as real for everybody, including her.
Columbo's first name or his wife's is never given. He is only known by his rank. Being that his wife is never seen. His badge does appear in several episodes showing his full signature but unfortunately never quite clearly enough to be read on VHS although it was clearly seen as "Frank" on the DVDs. Also in Trivial Pursuit and other games his name is a question and the answer is Philip, though this was placed as a trap by Fred L. Worth, to catch out those who infringed the copyright of his book, "The Trivia Encyclopedia". There was also a show called (among other things) Mrs. Columbo in which her name is revealed to be Kate, but again it is not considered canon.
Mac Taylor on CSI: NY. Mac *can* be a full name, but we've never found out for sure. Gary Sinise has said his name is McCanna (after Gary's son), but they've never said it onscreen.
Speaking of Danger Man, due to the concept of the lead character often going undercover, there are many episodes in which his real name, John Drake, is never uttered on screen and is only revealed in the closing credits. The US broadcast of the series, retitled Secret Agent, addresses the lack of name in its theme song "Secret Agent Man" ("They've given you a number/and taken away your name").
On Dark Angel, Max's friends went mostly by nicknames — Sketchy (Calvin Simon Theodore), Herbal Thought, and Original Cindy (say it out loud) (Cynthia McEachin). Her boss was referred to as Normal for the entire series, though a couple of jokes were made about his real name, eventually revealed to be Reagan Ronald.
The messenger boy in Dickensian is only called "Boy". Also Nell's grandfather, who was never named in The Old Curiosity Shop either.
Various Time Lords only go by titles, such the Arch-Enemy Time Lord the Master and minor Time Lord enemies the Rani, the War Chief, and the Monk. The latter four have had their names revealed in the Doctor Who Expanded Universe (The Master Koschei, the Rani Ushas, the War Chief Magnus, the Monk Mortimus) but not the Doctor.
The Doctor's name has never been revealed, with this mystery having been built straight into the show's title. The series initially implied that Time Lords did not have personal names, but this later got forgotten. River Song whispers the Doctor's name into his ear in "Forest of the Dead". The Doctor confirms it towards the end of the episode, though naturally the audience never hears it. Other episodes have alluded to his name being hidden in some dark secret ("The Girl in the Fireplace"; "The Shakespeare Code"; "The Fires of Pompeii"). The end of series 6 reveals there is one time and place where he can be asked who he is and must answer truthfully and that there are those willing to do anything to kill him and stop him ever answering, making the running gag below deadly serious.
In the classic series, UNIT stalwart Sergeant Benton was never referred to except as "Sergeant Benton" or "Benton". (In his first appearance he was "Corporal Benton".) The Fifth Doctor, long after the UNIT era, still referred to him as "Sergeant Benton" even after mentioning all of his other old UNIT pals by first and last name, and despite having also worked with Benton after he promoted to Warrant Officer. Fandom says his first name is John, probably derived from the name of the actor playing him (John Levene), but the name has only been used in expanded universe books and videos.
"Aliens of London"/"World War Three" subverts this. Here it was discovered that the alien enemies were not of a species named Slitheen; the word "Slitheen" was in fact their crime family's surname, similar to "The Sopranos". Their species name later turned out to be the extremely difficult to pronounce Raxacoricofallapatorians. As such, they were primarily known as the Slitheen, ever after.
In "The Pilot", Bill's previous crush (the girl to whom she served extra chips) isn't named the expanded universe seems to have decided her name is Lou.
Dr. Terrible's House of Horrible parodied this with a voodoo man who said "My name is...unimportant." Later, we see on his passport that his name is actually "Unim Portant".
Farscape has the Ancient Crichton meets in "Unrealized Reality". When John asks his name, the being simply states "Unimportant to our encounter." John then refers to him as "Einstein" in reference to their conversation about relativity.
On Firefly, Shepherd Book's real name was never revealed, not even in the movie or the comic-book adaptation. Derrial Book was the name he took from a man he killed.
The protagonist of Fleabag is never named. Although "Fleabag" is used as the character's nickname in publicity, even that's never used in-universe, and the credits simply say "starring Phoebe Waller-Bridge" without calling her character anything at all. Many of the other major characters go unnamed as well, being given nicknames or simply descriptions like "Godmother" and "The Priest".
Doc in Fraggle Rock. In the last episode his name is revealed to be Jerome Crystal (making him "Doc Crystal"; a pun on The Dark Crystal). Doc's multinational counterparts were mostly called Doc as well; exceptions include Norway's Oppfinneren (the Inventor) and Britain's Captain, a lighthouse keeper (the Captain was later replaced by his nephew, who was known as P.K., for "Principal Keeper").
A religious assassin sect called the Faceless Men has initiates give up their names and former lives as part of their training, so for example one of them is only known as "''waif''". Subverted in the case of Jaqen H'ghar, although that was almost certainly just part of his cover as a Lorathi criminal. This was briefly misunderstood by Arya when Jaqen (or another Faceless Man) told her that "no one" by the name Jaqen H'ghar was inside, leading her to believe that she'd gone on a wild goose chase.
Another example is the High Sparrow. High Septons of the Faith of the Seven leave behind their birth names when taking the position.
The Spice King insists his name is too long and hard for foreigners to pronounce, perhaps because he is a Canon Foreigner.
Played for Black Comedy when Arya says that as she'd never heard his name, she can't put Rorge on her death list (the names she recites before going to sleep of those she intends to kill). Rorge introduces himself, and Arya promptly kills him with a single stab in the heart.
The Baratheon General during the last stages of the march to Winterfell is never named in the series and is only credited as 'Baratheon General' in the casting bill.
The conceptual material for the series listed Gilligan's name as "Willy Gilligan", but during the series, it was used as a first name, with the last name never revealed.
Similarly, the Skipper (Jonas Grumby) and the Professor (Roy Hinkley) were known mainly by their titles.
Mrs. Howell was called Lovey but this was a nickname. Her real first name, Eunice, was mentioned in only one episode.
Glee: Puck's little sister. Granted, she's only shown up once so far, and that was in a flashback, but it still poses a problem for fanfic writers who want to include her. Surprisingly many of them call her Sarah.
Cappie in Greek. Though it's not that all of the characters don't know his real name; in fact, one of them threatened to reveal it to everybody as blackmail. He quickly complied. It was revealed in the final episode that his real name is Captain John Paul Jones. Similarly Beaver was known as that for most of the series and his name was just revealed a few episodes earlier to be Walter Boudreaux, only his girlfriend calls him by his name so when she asks for "Walter" nobody seems to know who he is.
In the black-and-white era series (lathough all filmed in colour and released colour on DVD) Have Gun Will Travel, the main character is only ever known as Paladin. Some have thought that a Sheriff called him as 'Bobby' but he was actually addressing another character.
Supposedly, some audience members thought his name was Will. Will Travel. Because that's what it said on his business cards. Have Gun - Will Travel.
His business card also inspired the joke that his first name was "Wire", since it read "Wire Paladin/San Francisco".
Noah Bennet is first credited as "Horn-Rimmed Glasses", referring to his eyewear. In the third episode of the series he is revealed to be Claire's father, and so became referred to by various characters as "Mr. Bennet", but his first name remains a mystery. A lampshade is hung on this in one episode, in which his wife says, "It's so strange that you all refer to him as 'Mr. Bennet'. I've always just known him as—" before she is distracted by her dog. He finally reveals his first name, Noah, in the first season finale.
Mr. Bennet's partner, who appears fairly regularly, is never referred to as anything but "the Haitian". In season 4, people start calling him René out of the blue.
Mr. Bennet's previous partner doesn't appear to have a real name either. He's usually referred to as Claude, but that comes from a joke he made in an early appearance: "I'm Claude Rains! I'm The Invisible Man!"
Another man named after his nationality was The German, one of the escaped level five villains, who had magnetic powers. Knox tore his heart out in his second appearance, so his real name is unknown.
The fourth season of House features a legion of young doctors who are applying for a job with the title character. At the start, each one is given an identifying number. They're rarely brought up except for one woman, who only answers to "Thirteen". Even after she's hired and joins the cast as a regular, nobody says her actual name. House doesn't call anyone by their name if he can help it. The other finalists are given monikers such as Cutthroat Bitch and Bosley, and the audience doesn't learn their real names for a few more episodes. Thirteen's name is eventually revealed to be Dr. Remy Hadley, but everyone on the team, herself included, still calls her Thirteen.
The mother is not named throughout the show. Mostly justified in that none of the characters have met her yet, but great pains have been taken to conceal her name anyway. In "Girls vs. Suits", when Ted goes out with a PhD student who was the mother's roommate, she refers to the mother as "my roommate", even when she talks about her in some detail.
Ted's children, referred to in the credits as "Son" and "Daughter", but fandom often refers to them as "Luke" and "Leia" due to a throwaway gag. As of the episode "Unpause" the children's names are revealed to be Penny and Luke.
Wendy the Waitress' last name is never given. Made even funnier when it's revealed she married one of Marshall's coworkers, who is only known by his last name "Meeker".
Wendy's last name may be an enforced Riddle for the Ages, because the Ted of the year 2021 couldn't remember her name until she prompted him ("Hey! It's...uh...you...""Wendy the Waitress?""RIGHT! Wendy the Waitress!"), so one might assume the Ted of 2030, and everyone in the stories he tells, refers to her as Wendy the Waitress simply because the Ted of 2030 can't remember her last name. Like the girl whose name Future Ted couldn't remember and referred to as "Blah Blah", and so everyone in the past was depicted as calling her "Blah Blah" as well.
The recurring character The Waitress is never given a name. This is lampshaded in a number of occasions. Dennis admits to never remembering her name, and sorts his sex tape with her under "The Waitress." In a later episode, she hears Dee call her "The Waitress" and gets upset that she doesn't know her name.
Dennis: *answering his phone, we only hear his side* Hello? Who is this? Who? Oh! Why didn't you just say The Waitress?
The real name of Mac is not revealed until season 7, when at their high school reunion it is revealed to be Ronald McDonald. No surprise as to why he goes by "Mac".
The Lawyer who opposes them in legal cases has never been given a proper name.
Jeeves, from Jeeves and Wooster, is universally known simply by his last name. It isn't until the final episode that we hear someone address him as "Reggie", presumably for Reginald. Unfortunately, many descriptions of the character freely use his full name, which rather spoils the surprise.
The main character in the one season series John Doe does not know his name - nor his history. All through the series, he tries to find out who he is. His name remains unknown (up to the point that the producers of the show never made one). John Doe is a name used by law enforcement agencies to refer to unknown male people (dead or alive).
In Knight Squad, The princess (Ciara's alter ego), is only ever referred to as "the princess". It isn't known if her name is actually Ciara.
In Leverage, the characters of Parker and Sophie Devereaux are both within this trope. Parker is Only One Name and as a foster child may have no other name, nor a need for one as she has no life outside being a thief. "Sophie Devereaux" is just Sophie's favorite of many aliases, and her real name is yet to be revealed.
On TV and in the radio, The Lone Ranger was this trope. We know his last name was Reid, like his brother and great grand-nephew The Green Hornet, but we never learn his first name in those versions. It is given as 'John' in later media. In the final chapter of the 1938 Republic The Lone Ranger movie serial, he is revealed to be Texas Ranger Allen King. In the second serial, The Lone Ranger Rides Again, he identifies himself as "Bill Andrews".
Jacob's enemy seemingly has no name, just that title - or "The Man in Black" (first seen in ABC's official recap - the press release called him "Man #2" - and actually used in-show by characters). Fans use Esau, Jacob's Nemesis and Mr. X.
Somewhat justified in "Across the Sea". His mom didn't know that she was giving birth to twins and intended to name her son Jacob. Right after the second baby was born, the mid-wife killed her and apparently never bothered to given Jacob's twin brother a name.
The mother in "Across the Sea" also has no name but "Woman". Only two characters in the episode, Jacob and Claudia, have names in fact... which makes discussing it rather difficult.
According to Entertainment Weekly, the scripts called MIB "Samuel", the same name used in the (intentionally misleading) casting call. However, it's not known if this is actually his name or not (given that they also kept calling Terry O'Quinn's character "Locke" after he wasn't regularly playing Locke anymore, it could easily just be out of convenience instead of something canon).
The SmokeMonster has never been named on the show. This has led to more than one scene where characters who were not in the main cast from the start wonder what exactly is meant by "the monster", or otherwise are forced to go out of their way to explain.
MacGyver's first name was only revealed in the series finale.note It's "Angus", by the way.
In Malcolm in the Middle, the family's last name is never spoken, but during the pilot, Francis wears a nametag that reads "Wilkerson", and during a deleted scene shown on the first season DVD, the name Wilkerson is also said. The pilot's script also refers to the family with the name Wilkerson.
Man in a Suitcase featured an ex-CIA man turned Private Eye who was known only as McGill. Supposedly his first name was John, but it was never used onscreen.
Radar's real name (Walter) wasn't revealed until episode 81 ("Quo Vadis, Captain Chandler?") in season 4, even though it appears in the very first sentence of the original novel.
Dr. B.J. Hunnicutt insists that his name was given to him by his mother, Bea Hunnicutt, and his father, Jay Hunnicutt, and his official Army files list only his initials.
Sparky's real name is never revealed. Not his first name, but he's Staff Sergeant Pryor (as shown in the Season 1 episode "Tuttle").
In The Middleman the titular hero is very careful about his name. As demonstrated in this exchange just after a truth gas has been released into the room:
Wendy: So if I were to ask you anything right now, you'd have to tell the truth? The Middleman: Yes, I would. Wendy: What's your real name? The Middleman: The same as my father's.
The unproduced 13th episode, read at Comic-Con by the cast and made into a graphic novel, reveals it. It's Clarence Coulton. Javier Grillo-Marxach, the creator, pauses the read-through for a moment, and then says to the audience, "Yes, that's his name."
In Mr. Bean, the title character's first name was never revealed although "Mr" and "Rowan" are seen, on different occasions, in the first name section of his passport. The book Mr. Bean's Diary included an old report card on which his first name was covered by an ink stain.
Not only is Mr. Lucky's first name never revealed, it's not even specified whether "Andamo" is his sidekick's first or last name.
The Broons are parodied in a Naked Video sketch, where the Twins and the Bairn are taken into care, to be looked after by someone who'd give them care and attention... and names.
Nobody knows C.C. Babcock's full name in The Nanny until it's revealed in the final episode: Chastity Claire Babcock.
In NCIS: Los Angeles, the leading agent of the team, Callen, has no first name. Not even he knows his first name. All we know is that it starts with "G". The others refer to him as "Callen", "Agent Callen", "G. Callen", "G", or "Mr. Callen". Even during the most recent season finale where Hetty leaves her position at NCIS to get a Romanian crime family off Callen's back by faking G's death certificate (complete with video evidence of G's death), we never know his first name. To maintain the mystique surrounding G's name they probably had the first name on the form illegible except for the G, knowing that someone with a DVR could just pause at that exact moment to see it.
Several characters in Ned's Declassified School Survival Guide are known only by nicknames. This is taken farthest with Coconut Head — his real name is obscured by tape with "COCONUT HEAD" on the wall of student pictures, he is named only as Coconut Head by teachers, and in the yearbook. In the "Guide to Nicknames" episode, Moze agreed to call him by his real name (which wasn't revealed)... but only if he got a better haircut.
Many if not most series regulars on Nikita start out this way. The title character stays with no last name until roughly the middle of season 2, when a TV reporter reveals it as Meers. Michael, Amanda, and Percy have no last name through the season 2 finale.
Much like his Disney counterpart above, Prince Charming in Once Upon a Time is tough to pin a name on. When first encountered in Storybrooke, he's suffering from amnesia and can't even remember his cursed identity, and he's only referred to in the Enchanted Forest as "Prince Charming", an originally derisive nickname bestowed upon him by his future wife upon their first meeting. Later it's discovered that his cursed identity is David Nolan, and he is known to many of those in the Enchanted Forest as "Prince James", but this is in fact the name of his twin brother whom he was forced to replace when James got himself killed. It's not until Season 2 that he reveals that his real name is David, the same as his Storybrooke name.
Grandad's first name "Ted" was only revealed in the Only Fools and Horses book series The Bible of Peckham and the pilot episode of Rock and Chips.
Although he appears in every scene of "The Light Brigade", the cadet is never named.
None of the characters in "The Camp" are named. The android overseers seemingly don't have names, while the human slaves are referred to by serial numbers. However, two of the slaves are given the names Tali and Alex in the sequel "Promised Land".
In "The Human Operators", neither the man nor the woman appear to have names. Ship only refers to her as "the female". The man's father is also never named. He simply calls him "my father".
In "Decompression", the Time Traveler is not named.
In "The Grid", the young girl who tells Scott Bowman about the computer controlling the people of Halford is not named.
One character's name has never (so far) been spoken on screen. The name "Pennsylvania Two" was used for the character in the press release for "No Good Deed;" in the press releases for "The Contingency" and "Bad Code," he's referred to as "Special Counsel".
There's also the fact that the names of the two main characters are aliases. While Reese's first name actually is 'John', his real surname is never revealed. Midway through the third season, flashbacks confirmed that 'Harold' really is Finch's first name, but his last name remains unknown.
The real name of Elias' second-in-command is never spoken by any character, and only seen on-screen when the Machine is assessing him; he's also only credited by his nickname. This changes in "The Devil You Know", where it turns out that Elias is very much on a first-name basis with him.
Reese: Anthony, huh? Guess I just always thought of him as Scarface.
Two Sixth Ranger types in Power Rangers Turbo and Power Rangers Lost Galaxy never have their true identities revealed: The Phantom Ranger, and the original Magna Defender. Other Rangers have gone with only first names ever mentioned on camera. These include original Ranger Billy, Mystic Force sisters Madison and Vida, Samurai Rangers Mike, Kevin and Emily, Megaforce Rangers Troy, Noah, Jake, Gia and Emma. (Last names for all but the Samurai Rangers have been revealed in other media. Billy Cranston, Madison and Vida Rocca, Troy Burrows, Noah Carver, Jake Holling, Gia Moran and Emma Goodall.) There are also numerous Rangers of extra-terrestrial origin who are known only by one name, but it is possible that there planets do not have last names. (Andros, Zhane, Maya, Karone, Orion and the Rangers from Aquitar.)
Jarod, Sydney, Jacob, Brigitte, Sam the Cleaner, Willie the Cleaner, Angelo, Major Charles, Margaret, Emily, and Kyle are only known by their first names, and no last names are ever given.
Miss Parker, Mr. Parker, Broots, and Mr. Fenigor are only known by their last names, and no first names are ever given.
Only William Raines, Debbie Broots, and Catherine Parker (née Jamieson) get full names.
Mr. Lyle is an interesting case, as that's an alias he adopted, and he may not even have a first name. One episode does reveal his full childhood name — Bobby Bowman — but he would probably argue that that's not his name any more, if it ever really was.
Number Six and many other residents of The Village in The Prisoner (1967). (It is officially denied that Six is John Drake, a spy previously played by the same actor in Danger Man because although the same company owned both shows, that character was created by another writer who is not credited in the later series.)
Quincy, M.E. is called one of four things: "Quincy", "Dr. Quincy", "Doctor" or "Quince" - while one episode has a shot of his business card showing his first name begins with the letter R, said name is never used. Not even by his girlfriends. Not even by the officiating pastor in "Quincy's Wedding, Part 2" when the main man takes a new bride!
This trope turns up in mainstream shows too: British nostalgic hospital drama The Royal has a major character known only as Matron.
The ronin of Samurai Gourmet is never given a name despite appearing in every episode. Since he is imaginary, this is probably because protagonist Kasumi is Genre Savvy to stories like Yojimbo.
Princess: Samurai-sama! What is your name? Samurai: I am not worthy of a name.
One of the main characters in Scrubs is simply known as "The Janitor". His nametag and uniform also just say "Janitor", and he even calls himself "Dr. Jan Itor" when pretending to be a doctor. It was said (jokingly) that when the Janitor's name is revealed, the series will be over. One episode features JD discovering that the Janitor had a role in the film The Fugitive, suggesting that the Janitor is actually supposed to be the actor portraying him (Neil Flynn), fallen on hard times. In one episode he fools J.D. by signing his name as "Dr. Rotinaj". In the last episode though, he reveals to JD that his name is "Glenn Matthews". He never revealed his name, because no one ever asked. Someone immediately calls him "Tony", making the revelation dubious, but Word of God has confirmed that it is his real name.
Elmo from Sesame Street was a minor background Muppet simply known as "Baby Monster" prior to 1985, when his current character started to take shape.
Mr. Big on Sex and the City. His first name was revealed in the last episode of the series. He gets a full name and e-mail address in The Movie.
Sherlock: Mycroft's Girl Friday introduces herself to John as "Anthea". She cheerfully admits it's not her real name about ten seconds later.
In Simon And The Witch, the witch and Simon's mother are never named. This is turned into a running gag with the former being called "Mrs... Er..." or "old tatty lady" and the latter "Mrs Woman". Simon and Sally's surnames are never revealed.
The title character in Spartacus: Blood and Sand, believe it or not. Batiatus remarks that he fights like Spartacus, the legendary Thracian king of old, after Legatus Glaber explains the he had never bothered to learn his name. Every time Spartacus attempts to mention his real name he is cut off by other characters, oftentimes on purpose, to make clear that his old life is over.
All Wraith on Stargate Atlantis, with the implication that they have names, but they just don't give them out to other species. To compensate, Sheppard gives them common names like Todd and Michael.
The character played by Majel Barrett in the first series pilot, "The Cage", is referred to only as "Number One", the unofficial nickname attached to her position as Captain Pike's first officer.
Neither of the two main Romulan adversaries in the series were ever referred to by name, but simply as "the Romulan Commander".
On Star Trek: Voyager, The Doctor (the Emergency Medical Hologram, not that one) went seven years without getting a name that stuck. In the last episode, he's portrayed as finally having settled on "Joe", but that was in a future that got erased. note Word of God is that he was originally named Dr Zimmerman in the script, but they managed to go long enough without mentioning his name onscreen that it became a plot point of its own.
On Star Trek: Deep Space Nine, none of the Changelings have names, and the 'leader' only goes by 'Female Changeling' or 'Founder'. Odo and Laas only have names because they have interacted with 'solids' and we like to place names on things.
In Supernatural, the names of the supernatural characters are often not given.
The original Big Bad was called the "The demon that killed mom and Jess" or simply "The Demon" for much of Season 1, as that was all they knew about him. After seeing he had yellow eyes, he became known by his arguably most iconic name "The Yellow-Eyed Demon". His name was finally revealed to be Azazel in Season 3 after his death, by another demon who even comments "You didn't really think we all called him the Yellow-Eyed Demon do you?"
Many other demons are only known by their hosts name. Meg Masters is explicitly the name of the demon's first host, but the characters all call her Meg even after she gets a new host (who probably wasn't also named Meg). She has a name, but it never gets revealed. To the point that on the Supernatural wiki, "Meg" is the demon's page, but "Meg Masters" is her host's page. The demon possessing Tammi in "Malleus Maleficarum" never has her name revealed, but supplementary material lists it as Astaroth.
The Leviathans follow the demons, and are known by their host's name. The Big Bad's true name is certainly not Dick Roman, but it is all he is ever called. Given their age, they might not even have names. None that humans can understand or pronounce anyway.
Tata, a Marcin powiedział... is a truly spectacular case, because neither of the main characters is named, despite the duo of the father and the son being the only characters on screen. The series was running for seven years, with 287 episodes.
Stiles' first name is unknown, and is supposedly embarrassing and very hard to pronounce. According to his dad, Stiles himself was the one who decided that he wanted to be called Stiles, which is derived from their last name, Stilinski.
Fez, That '70s Show. Fez is short for Foreign Exchange Student. At one point, someone asks his real name and he is drowned out by a school-bell while seen saying an incredibly long name. (In that scene, actor Wilmer Valderrama was actually saying the first names of all the cast members.) His friends call him Fez because his real name is too long to easily remember or pronounce.
There are several in the UK sitcom Time Gentlemen Please. The landlord is usually referred to as 'Guv' (and other less pleasant nicknames), the old man never tells anyone his name ("I'd rather not say, sometimes you just want to go where no-one knows your name"), and of all the regulars in the pub we only ever hear Terry's full name. Even the pub itself isn't named until the second series when the brewery needs to know the name and nobody, not even the landlord, has any idea what it is, having always simply referred to it as 'the pub by the chemical works'. All this is lampshaded in one episode when the old man is using the telephone: "Hello, it's the old man with no name in the pub with no name."
Top Gear: The Stig. It's not clear what this nickname even means. "Some say that he was born of a planet that has no concept of 'naming'..."
In Torchwood, the real name of Captain Jack Harkness is never revealed. A flashback to his childhood has his parents repeatedly addressing him as "son" while calling Jack's brother Gray by his real name. The EU eventually (nearly twelve years after the character's first appearance!) gives his real name, the rather awkward 'Javic Piotr Thane'. It's no wonder he changed it.
Almost none of the characters in Trailer Park Boys have any last names given. Given that they're often in court for their various crimes, this becomes comical as the judge always just refers to them as Ricky, Jules, Bubbles, etc. (especially Bubbles, as this is explicitly said to be a nickname. We never find out his real first or last name). Jim Lahey and his related family (and Sam Lasco) are the only recurring characters who get both first and last names.
This was the case for some time in True Blood with Andy's daughters who rapidly aged until they hit 18, if you don't count numbers as names. It was only after three of them were killed that he gave them actual names.
The species of the alien invaders in UFO is never mentioned. Even the members of SHADO never use a codename, but simply call them 'the aliens'.
Well, how would anyone know what species they are? If we were sneaking around an alien planet trying to take it over, I doubt we'd be wearing a sign saying "humans" or "Earthlings".
In any case, it is revealed that the UFO pilots themselves are not aliens, but abducted humans possessed by alien intelligences.
Westworld: Until it is revealed that he is actually William in a different timeline no name is given to The Man in Black.
In The X-Files, Deep Throat's real name is not given until the fourth season, despite the character's prominence in the first season. The second season premier implies that Mulder knows it, but he never speaks it onscreen. In the fourth season flashback episode, he and the Cigarette Smoking Man are the main characters, and the Cigarette Smoking Man calls him Ronald.
In season 10 is revealed that Deep Throat's real name is Ronald Pakula, after his grave is shown.
The Cigarette Smoking Man is later referred to by the name C.G.B. Spender, though Scully believed it's just an alias and not his real name. His name was also confirmed in Season 10 as Carl Gerhard Bush Spender
The X-Files was full of this trope, many of the main conspirators are never named and are often known solely by the descriptive terms used in the credits. There's Mr. X, The Well-Manicured Man, The Grey-Haired Man, Second Elder, Third Elder, Toothpick Man, Quiet Willy, The Red-Haired Man, and so on and so forth.