The worlds created by large comic book companies are a curious thing. Since there's many different titles being published simultaneously, an odd effect can occur; when a character is set aside, they can seem to vanish from the universe; not being mentioned, spoken of, or appearing in any situation one would expect them in.
This usually occurs to characters who have had their titles canceled and found no appropriate series to migrate to. Many characters, especially supporting characters or those without powers, are permanently stuck in comic book limbo.
Sometimes this is a direct choice on the part of the editorial staff. For instance, in the '90s, Hawkman and his family were purposefully put into Comic Book Limbo because the editors decided that he'd only shown up a few years ago — after other writers had put him into the founding of the Justice League of America. So an alien spy had been masquerading as him in the interim, except when he hadn't, except that he still knew the characters that knew the alien spy him, and then they didn't know if the reincarnated magical pharaoh Hawkman was related to him or not, and then they merged into the even more confusing Hawk-God, and... at this point, limbo becomes a mercy.
Characters can be brought back from limbo at the writer's discretion, unlike a Comic Book Death, where they at least have to give the semblance of having an explanation of why they're back. The likelihood of such a thing happening usually depends entirely on how much the writer likes said character.
C-List characters are often brought back from limbo just to be killed off as part of a Tonight, Someone Dies event. For instance, this happened to several third-string Teen Titans members during Infinite Crisis.
Series with a lot of Meta Fiction often parody this concept by having characters that were banished to a literal limbo, usually just because people forgot about them (or, if the series is Lighter and Softer, a literal game of limbo).
Compare Chuck Cunningham Syndrome.
- During Grant Morrison's highly metafictional run on Animal Man, the eponymous character actually visits Comic Book Limbo.
- Another literal comic book limbo appeared in the final issue of Marvel Comics Silver Sable title. The writers used the Li'l Sylvie comedy back-up strip to comment on the cancellation of the book by having Sylvie (a chibi version of Silver Sable) banished to a limbo inhabited by chibi versions of female Marvel characters who had once headlined their own books.
- Deadpool - After his series was almost cancelled, he had a dream in which he sits in camp with heroes of many closed titles.
- Irredeemable Ant-Man - The last issue's cover shows the titular character fighting many forgotten heroes and screaming that he will never share their fate.
- Magog has entered this since leaving the JSA and his own series turned out poorly.
- The Doctor Thirteen: Architecture and Morality backup had The DCU's premier skeptic exploring Comic Book Limbo and coming into conflict with the shapers of the universe (who bear a strange similarity to the authors working on 52).
- Captain Carrot and His Amazing Zoo Crew! after the Oz/Wonderland miniseries generally only ever appeared as background gags or in Take Thats to their comparatively Lighter and Softer tone.
- Darkhawk was in limbo for a few years, recently returning in a few crossovers.
- Of all characters, the X-Men were technically placed in limbo for about half a year in the 70's. Their series was put on hiatus and only reprints were being published with Marvel contemplating cancelling it all together. Luckily, writer Len Wein (who was soon replaced by Chris Claremont) and artist Dave Cockrum restarted the book with an all new team featuring a certain short guy with claws, and the rest was history.
- The most frequent victims of this (even by X-Men standards) are any of the younger generation X-Men. After Grant Morrison finished up New X-Men, virtually all of them disappeared save one or two who act as sort of 'flagbearers' for that class like Husk and Pixie. The practice became so common that fans call it "becoming wallpaper" since the only time those characters will be seen again is in wide background shots of huge groups of mutants.
- Occasionally occurs in The Beano and The Dandy with past characters disappearing from the two Anthology Comics for years before returning. One character, Lord Snooty, disappeared for almost 20 years - then his grandson, Lord Snooty the Third, appeared, heavily implying that the original Snooty was dead (he'd need to be for the younger Snooty to inherit the Lordship), an unusually dark scenario for the Beano. Occasionally characters brought back are heavily redesigned or openly mocked for appearing odd to a modern audience (see Keyhole Kate and Pansy Potter's treatment in one of Kev F Sutherland's strips [http://utproductions.co.uk/scary1.html]).
- Gold Key's Hanna-Barbera Fun-In, which started in November 1969 and featured H-B characters from 1969 and 1970, went into limbo after issue #10. It returned in February 1974 for five issues and featured characters from mainly 1973 shows (except for issue #13, which featured The Hair Bear Bunch from 1971).
- Several supporting DC Comics characters vanished after the New 52 Reboot. Over a year later after the reboot, and it was still unclear whether characters like Spoiler, Renee Montoya, and Cassandra Cain were still alive or ever existed. Fortunately, they did later return.
- Even before the New 52 Reboot, a Superman supporting character named Keith received this treatment. This wouldn't be so strange except that they'd developed the character to the point where he was actually adopted by Perry White.
- In the Bronze Age, Marv Wolfman created a team called the Forgotten Heroes, whose members were old Silver Age characters that hadn't appeared in years, like Cave Carson, Rip Hunter, Dolphin, and Animal Man. Animal Man has become a more prominent character since then, but the others are still pretty obscure even today.
- Crystar, crystal warrior and his supporting cast on planet Crystalium haven't been seen since their 1980's series. Despite having been part of a toy tie-in, Marvel owns all rights to the characters and could bring them back at any time.
- The Powerpuff Girls saw its final comic book appearance under DC Comics in July of 2009 in issue #59 of Cartoon Network Block Party (its final issue as a singular title was issue #70 in January 2007). IDW revived it in September 2013.
- The Unbelievable Gwenpool has No Fourth Wall which leads to End-of-Series Awareness when her ongoing is about to be cancelled. So, not only is she aware of her own demise, she knows her entire supporting cast will disappear as well. And even if another writer decides to use them in the future, he will twist their personalities to fit whatever story he has in mind.
- Epic Mickey takes place in Wasteland, which is basically Walt Disney Cartoon Limbo.
- SNK used to have several fighting game series, but most have been apparently abandoned, the the only way some character from the older series ever return is through the The King of Fighters series - so there's official artwork of several near-forgotten characters in out-of-focus games waiting for their turn at a KoF return in a locker room◊, which is functionally SNK limbo. Some like Hwa Jai have managed to return from it though.
- Deep Fried briefly recruited Lyman, mainly known in his home-comic for being absent since the early days of the run, as a replacement for one of the main characters.
- Melonpool saw its title character visit an endless void inhabited by Calvin, Opus, and other characters from completed newspaper comics.
- In a dimension-hopping storyline in Real Life Comics, Greg and Tony end up in a blank room where forgotten characters sit around all day playing poker, including Greg's ex-girlfriend Lizzie (who asks if the author got tired of them too).
- This occurred a lot in the Global Guardians campaigns. When players left the game, or when individual campaigns shut down, their casts usually faded into the background, never to be seen again. Occasionally one would move from one campaign to another, but it was rare.