The very term "comic book". Unless you think Batman is hilarious. Whichhe is, but still....
The 'DC' in DC Comics originally stood for Detective Comics. Very few of their comics today feature actual detectives, and officially the acronym no longer has any meaning.note If it did, the company's name would be "Detective Comics Comics." Similarly, while the actual Detective Comics publication does feature Batman, "the world's greatest detective", many of the stories therein feature little or no actual detective work.
Similarly, Action Comics was intended to be an anthology title of, well, action comics. The debut of Superman in the first issue and his subsequent popularity led to the character taking over the line.
While Cable & Deadpool always had the tendency to focus more on the latter than the former, the title became obsolete once Cable (temporarily) died. They lampshaded this by crossing out the word "Cable" on the covers and replacing it with the name of the guest stars.
The comic "Batman and Robin" followed this formula as well after the death of Damian Wayne. Once the guest-stars stopped being a thing, it was Batman and Two-Face since it was a Two-Face arc. Then it involved Damian's resurrection so they kept the original title.
From #3 onwards of the comic series Nextwave, its official title was "Nextwave: Agents of H.A.T.E" (due to trademark issues). This was despite the fact they stopped being agents of H.A.T.E by the end of #1, giving it an Artifact Title from the beginning. This was lampshaded in every comics recap after it became irrelevant.
From the Disney Comics:
The "Stories" in Walt Disney's Comics and Stories were originally passages of text with minimal illustrations (and thus, "stories" about Disney characters) rather than actual comic strips. As those faded out of use in favour for comics, the official title of the series remained Walt Disney's Comics and Stories, but the title logo simply reads Walt Disney's Comics.
When Donald Duck's superhero alter-ego from the Italian comics, originally known as Paperinik, made its way into American comics in Disney Adventures, the characters was given the English name of the Duck Avenger, the obvious reason for the change being so that he'd have the same initials as the magazine. Nine years later, the Duck Avenger is still the character's official English name, even though Disney Adventures is no longer published.
The Italians Paperinik fans (and creators), who, you know, may have something to say about this, prefer to name him Phantom Duck.
The name "Paperinik' himself, however, is an artifact title itself; though it's widely unknown today, it was an allusion to a popular comic book and pulp novels Gentleman Thief named Diabolik, mixed with Donald's Italian name, Paperino. This made sense because the Duck Avenger/Phantom Duck's original adventures showed him as Chaotic Neutral, using more his secret identity and gadgets to avenge himself than to fight crime like in later, more politically correct and editor-friendly stories showed him to. Paperinik is no longer a Disney version of Diabolik, but her kept the name.
The "PK" science-fiction seriesnote PK standing for Paperni K, which are the Darker and Edgier version of Duck Avenger/Phantom Duck (using high-tech instead of cartoony gadgets and fighting an alien invasion), pushes the "Artifact Title" aspect of Paperinik even further, because at least, officially, in the "normal" continuity, the stories in which Donald used his secret identity to act like Diabolik are still canon; we're just supposed to believe that he got softer later and decided to use his powers for more virtuous purposes. "PK" pretended to keep this origin story, but in fact, the second series bearing that name (PK New Adventures) completely dropped the idea by saying that this version of the character never was the original Paperinik to begin with and only started to be a superhero when the alien invaders dropped by. This begged the question of where the name comes from, then. But in fact, the cast of the series had started to nickname Donald's identity simply "PK", like the title of the series, so eventually they retconned that PK stood for some Canis Latinicus meaning "heroic duck" and decided that the series was an alternate universe altogether from the original stories.
In Vol. 4 of Mirage's Teenage Mutant Ninja Turtles series, the turtles are now in their thirties, having aged in real time since the original series.
Turtles however are a species with negligible senescence, meaning that they don't really age past sexual maturity. Speaking biologically, they are still teenaged.
2000AD's title was chosen in 1977 because it sounded futuristic. Publishers IPC Media didn't really think about this trope when they okayed it. They launched new titles on a regular basis, and the predicted lifespan of a children's title (as it was originally) was 18 months. In the 1990s there were a few attempts to change the name to something less "dated", all of which were roundly rejected by the fans. It's still called 2000 AD today. It's now more of a Badass Boast since the stance in Prog 2000 (the last issue released in 1999)note Since 1999, the prog that covers the Christmas / New Year period used the new year as the issue number, as of mid-late 2012 the regular weekly issues are "only" up to the early 1800s said "We were here first. The year can change its name."
None of the main characters in Knights of the Old Republic are (Jedi) Knights: Zayne is a Padawan who missed his first opportunity at knighting due to a combination of circumstances and later refused the offer of knighthood after clearing his name, and his companions never had any formal Jedi training (and most of them aren't even Force-sensitive). The comic inherited that title from the video game, which in turn got it from an even earlier arc of the Tales of the Jedi limited comic series.
When Jack Kirby and Joe Simon created the Newsboy Legion in The Golden Age of Comic Books, they were so-called because they were orphans who sold newspapers to earn a living. This had become an anachronism in later years, which was addressed in several different ways:
When Kirby introduced their identical sons in the Bronze Age, they were also known as the Newsboy Legion, even though they'd never sold a paper in their lives.
The current incarnation of the Legion are clones of the originals (the sons don't exist Post-Crisis), and they still don't sell papers.
Walter Simonson tried to bring them up-to-date in Orion as the Newsgroup Legion, a term more recently used by Jimmy Olsen (although it remains to be seen if he's talking about the same kids).
The home titles of DC Comics' Enemy Ace feature were Our Army At War and Star-Spangled War Stories. For the mostly-American readership, the tales of German World War One ace Hans von Hammer were neither "star-spangled" nor about "our" army.
Stephanie Brown, Batgirl 2009, originally operated under the superhero identity of the Spoiler. Her name and modus operandi came from her relationship with her father, the Cluemaster, who was a B-grade Riddler knockoff. Stephanie grew to despise her father and his criminal ways, so she would go out and leave clues to help Batman and Robin catch him, spoiling his crimes. However, Stephanie quickly branched out into crimefighting beyond her father and she no longer did any "spoiling", she would directly intervene and fight crime herself. She retained the name for years, not counting her brief tenure as the fourth Robin, and there became such a disconnect between her current activities and her original actions that even a lot of her fans did not know where her identity came from. In 2009, following the death of Batman, she inherited the Batgirl title from Cassandra Cain and the Spoiler identity was laid to rest. When she came back in New 52, she was back to her original motivation of spoiling her father's crimes.
DC Comics' World's Finest title has traditionally been a Superman-Batman teamup book. It evolved out of a 1940s World's Fair special comic.
The Marvel Comics line 2099 showcased the future of the Marvel Universe, including future versions of classic heroes. Initially, the comics took place in the year 2099. Instead of straining the confines of Comic-Book Time, Marvel allowed the titles to mention months and years going by, thus the titles eventually took place in the year 2100 and beyond.
The title of the graphic novel series 30 Days of Night refers to the period during the winter in Barrow, Alaska, during which the sun doesn't rise for 30 days straight. In the series, a legion of vampires takes advantage of this to go on a 30-day feeding frenzy without worrying about the sun. The series went on to take place in locations other than Alaska, but retained the title. The events in Barrow set most of the rest of the series in continuous motion by making vampires in danger of being exposed because of the huge massacre in Barrow. So it's partially justified in that the events in the first installment remain important as the series goes on.
The League of Extraordinary Gentlemen retains its title up until the very end, even though the eponymous League was officially disbanded sometime between the events of Century: 1910 and The Black Dossier. By the end, the main cast has ceased to be a "league" and become a dwindling "trio".
In a more general sense, the title of the series was originally supposed to reflect its Victorian setting, since it's the kind of name that a superhero team would have chosen for itself in the late 19th century. Said Victorian setting has been out the window since The Black Dossier (which took place in The Fifties), with the last two installments taking place in The '60s and the 2000s, respectively. The name simply remained the same because, in-universe, there was no actual reason to change it.
Some writers have tried to explain this as Kal El being the last male child born on Krypton.
After Crisis on Infinite Earths, DC got rid of all the other Kryptonians and made Superman the last son of Krypton again. Didn't stick.
In the 1940s, Fiction House had a series called Werewolf Hunter, featuring Professor Armand Broussard, an Occult Detective. While his first appearance had him facing a werewolf, most of his subsequent stories had nothing to do with werewolves.
In his early stories, Desperate Dan was something of a villain, hence his title. However, Characterization Marches On, and he soon developed into a likeable doofus with super-strength, about as far from a desperado as you could get.
Suzie Comics published by Archie Comics in The Forties and The Fifties originally focused on the titular heroine - a beautiful but ditzy young woman who was forever losing jobs due to her ineptness. She eventually gained a friend called Ferdie (who ranged between Unlucky Childhood Friend and actual boyfriend depending on the issue) who slowly came to dominate the comic. By the time the comic ended in 1954 it was still named after Suzie and she continued to appear on the cover but Ferdie was the real star with Suzie largely resricted to playing his Straight Man love interest.
Stark Tower technician: Look, all I'm saying is, his suits aren't even made out of iron anymore. Boss should be calling himself Ceramically-Enhanced Alloy Man while he's in San Fran.
Werewolf by Night hasn't been restricted to being a werewolf only at night since the end of his first solo series in the 1970s.
Not exactly a series title, but the name of the X-Men foes "The Brotherhood of Evil Mutants" became a bit obsolete when Magneto was recharacterized as a Well-Intentioned Extremist as opposed to a Card-Carrying Villain. Usually they justify it by Magneto intentionally invoking Then Let Me Be Evil. Some versions have just been called "the Brotherhood of Mutants".
"Comic-Con" (In particular the annual one in San Diego, California) has essentially become this. Originally, it was a comic book convention that also supported fandoms for the Science Fiction and Fantasy genres as well as related genres such as Anime. Logical, since these genres tend to cross-pollinate each other. Today, the event has mutated into a Hollywood/Pop Culture/Celebrity festival where comic books are relegated to one small corner and most of the comic book related events are related to the mainstream cinematic adaptations of these properties. And it is not unusual for festivities to include non-genre fare such as Glee or Breaking Bad. This has become a subject of discontent amongst hardcore, Old School fans who feel that many of the newcomers are there just for the scene.
Plenty of superhero teams have gone under the names of "new" or "young", even when the team has been around for a while and the members have grown up. The New Mutants and the New Warriors are prominent examples. The Teen Titans also frequently verge into this, with many of the core membership being in their twenties.
When the IDW Star Trek comic was retelling Star Trek: The Original Series episodes in the reboot movieverse, "Return of the Archons" became this. In the original episode, the Betans are humanoid aliens who have a vague history that 100 years earlier the USS Archon visited them and was destroyed by Landru, calling the crew "the Archons". They recognise the Enterprise crew as being the same, therefore this is the return of the Archons. In the comic, the Betans are a Lost Colony who have built a shrine to Landru out of the Archon, and the idea that Starfleet outsiders are "Archons" doesn't exist.
In Loki: Agent of Asgard, the protagonist quit working for Asgard in the end of the final arc (in issue #5). The title subtitle stuck till the series' end.