In DC Comics, this problem was temporarily deferred from the 1960s to the mid-1980s by introducing parallel universes, where the original version of a long-running character lived on "Earth-Two" and aged, while the current version of the character did not age, but lacked most of the long history. Earth-Two was destroyed in 1986 in Crisis on Infinite Earths, but Crisis also reset the histories of many characters, again halting the problem for a few decades. The whole thing was, however, done piecemeal and in an inconsistent way; Batman, for instance, has only had minor resets done, and his history back to the 1960s still has to fit in the aforementioned "about twelve years".
However, characters which existed only in Earth-Two and were re-integrated as the Justice Society were allowed to bring along their age: Alan Scott as Green Lantern, Jay Garrick as The Flash, Wildcat, and the original Hourman have all visibly aged. Even still, Jay Garrick is looking remarkably well-preserved these days for someone who should be pushing 100 years old.
A notable, headache-inducing sidenote for the Earth-Two characters is that Earth-Two used a rough approximation of real time while Earth-One used Comic-Book Time. The fact that the two crossed over regularly was only going to get more bizarre as time went on if it hadn't been halted by Crisis.
Another consequence of this is the utter retcon of Black Canary, originally from Earth-Two and Green Arrow's on-again/off-again love interest. Originally an older woman, she's now clearly younger than Ollie's given age of early 40s, possibly by as much as a decade. It doesn't sound so bad until you put the couple into context with Nightwing. Ollie's infamous in-universe for being a Batman copycat, so everything Batman's done, Ollie did a little later, like get a sidekick. Speedy (later Arsenal, later still Red Arrow, and now Arsenal again) is clearly a year or two at most behind Nightwing in age. In his late teens, Speedy also had a drug problem, from which Black Canary helped him recover while she and Ollie were split. The experience tied Black Canary and Speedy together so closely that they consider each other mother and son. The problem is that this story was written when Black Canary was in her mid-30s, Ollie in his late 20s, and Speedy in his mid-teens. The timeframe now is such that only seven years at the most separate Black Canary and Speedy in age, so even assuming Black Canary was exceptionally mature for her age, the "mother" moniker would be unlikely. Even more egregious is, of course, that if this occurred approximately ten years ago in continuity, she and Ollie would have been very early in their relationship, and more importantly, she'd have barely known Speedy, who had turned to drugs after an extended absence from Ollie.
The "fix" applied to Black Canary (circa 1980) was that she suddenly discovered that she was actually her own daughter, with false memories.
The Stargirl (2020) TV series tries to avert the whole thing by having the JSA's adventures taken place in the (relatively) recent past, with the Golden Age of heroes having ended ten years ago rather than after World War 2.
This isn't even consistent among all writers. Brad Meltzer, for example, had Elongated Man muse that he'd been a hero for almost two decades in the opening pages of Identity Crisis (2004).
The maxi-series 52, which covered the "One Year Jump", was notable for being explicitly real time, with each of the 52 weekly issues covering the week since the last release.
Its weekly sequel, Countdown to Final Crisis, claimed to be real time early on, yet took place concurrently with the rest of the Comic-Book Time DCU.
The confusion was caused by Countdown to Final Crisis. Because of DC's original stance that Countdown was going to be in real time like 52, Geoff Johns initially believed that Final Crisis was going to occur "two years" after Infinite Crisis (a panel in an early issue of Booster Gold stated "Week 104, The Final Crisis"). But since Countdown was shunted into "vague what-ever time" status… yeah. Or maybe Geoff doesn't know how long it's been since Infinite Crisis… no one can say.
This trope is taken advantage of in the Batman: Hush storyline, where a flashback has Bruce Wayne, age 8 or so (before his parents' murder), watching the original Green Lantern Alan Scott fight his enemy the Icicle. Originally, both superheroes were active at the same time (Batman's even "older" in terms of publication history!), but because the issue of Comic-Book Time was handled differently for each of them, Alan Scott was active as Green Lantern when Batman was a kid.
Infinite Frontier and Dawn of DC have taken a much more relaxed "everything is canon" approach. The most striking results of this are on Batman, who is now written and drawn as being visibly middle aged, complete with greying hair, and has his advancing age, the problems it represents for his crimefighting, and the knowledge that almost all of his children (adopted or not) are well into adulthood by now as major themes of his comics.
Also of note is how back in Emerald Twilight in the early 90s, Hal Jordan was depicted with grey hair as if he were old which was retconned as a sign of Parallax possessing him to keep the sliding timescale — which said Hal was young — intact. Fast-forward to Green Lantern (2023) and has Hal's hair turning grey naturally because canon now dictates that he's been Green Lantern for several decades now.
Batman has been protecting Gotham City for about a decade. Batman has always been protecting Gotham City for about a decade.
Interestingly, the movie Bruce Wayne and his parents went to see has consistently been The Mark of Zorro starring Tyrone Power. This movie's first theatrical run was in 1940. This would place Bruce in his 80s. It's probably only a matter of time before he went to see the Antonio Banderas version from 1998. Quite frankly, at this point there is nothing stopping the ten-year old Bruce from watching the 1989 Batman movie.
Selina Kyle: I've known the Departed since... well, it was a couple of years before Pearl Harbor. I guess that dates me.
After Infinite Crisis, it's closer to twelve years, one of which was covered by the "One Year Later" jump.
The Batman is a textbook example of adaptations avoiding this; it starts right when Batman has been around for three years, and advances in time as it goes along (in the third season Batgirl was in High School, and in the fifth we discover she's already started college; Robin also gets noticeably taller in the fifth season).
The rebooted Post-Flashpoint timeline has Batman's career condensed to five years. This has caused a major continuity snarl, in that Bruce's son Damian is still established as being around 10 years old, and yet flashbacks show that Bruce was already Batman when he first met Damian's mother Talia. It was later retconned that Damian was artificially aged up.
It has now been said that Batman has only really been in the public spotlight for five years, and there are years before where he was doing his whole "mysterious urban legend" thing. Then Scott Snyder wrote "Zero Year", which establishes that Bruce didn't really have an urban legend phase at all, and has indeed only been Batman for about five years. Oops.
In the very first issue of Harley's Little Black Book, it's said that Harley Quinn is a closet Wonder Woman fan, and a Flashback shows that she owned an officially licensed Wonder Woman costume (which also had a picture of Batgirl on the box) when she was a little girl. Such a revelation already would have been pushing things in the pre-New 52 continuity, but post-New 52 and with the revelation that Wonder Woman only came to America around five years ago, it makes absolutely no sense whatsoever. Given that Harley Quinn generally runs on Rule of Funny, that might be the point. Ironically, it made more sense after the next retcon, with Wonder Woman #750 establishing that DC Rebirth Diana made her debut in 1941.
Batman has been the same general age as three full generations of a Legacy Character.
A negative review of The Brave and the Bold #33 cited the fact that the issue (which is a Whole Issue Flashback set just before The Killing Joke) features a scene where Batgirl, Wonder Woman and Zatanna sing "Single Ladies (Put a Ring on It)" by Beyoncé. The song came out in 2008, while the issue was published in 2010, meaning that the story is essentially implying that Barbara Gordon's entire history as Oracle took place in under two years.
In the Tomasi run on Detective Comics, Astrid, the future Arkham Knight, was born during a fight between Batman and a whole bunch of Arkham inmates (including characters who traditionally didn't appear until Batman was established for a while, like Harley) and is now an adult. Figure that one out.
As observed above, all of this has been more or less thrown out by the arrival of Infinite Frontier's more fluid approach to continuity and willingness to let the characters age. The Chip Zdarsky run on Batman's main title explicitly establishes Bruce as now being middle aged, in his very early fifties at minimum, which for once actually makes sense if one presumes he has been aging in more or less real time since Crisis On Infinite Earths. This extends to the rest of the Batfamily as well; of Bruce's various sidekicks and children — adopted or otherwise — only Damien (who was a child no older than 8 to 10 when introduced and spent several years being dead before being resurrected at the same age he died) is still especially young. All the others are now adults in their twenties to mid-thirties despite each being introduced as teenagers. Meanwhile, the now dead Alfred is treated as having been near senior citizen when he died.
Pre-Crisis, Superman was always, officially, 29 years old. It actually became a plot point in one story where a hippie had gained supernatural powers and magically barred everyone over thirty from entering Metropolis. Superman could enter because he was 29.note Head editor Julius Schwartz jokingly claimed this was because his birthday was February 29, meaning he "only" aged on Leap Years. Probably the most famous use of this was in For the Man Who Has Everything.
Averted in John Byrne's Superman & Batman: Generations series, which operated under the premise of "what if comic books followed real time from the beginning." Kal-El and Bruce Wayne make their heroic debuts in the late 1930s, as in real life, but then proceed to age and have families, with their children taking up their respective heroic legacies. Eventually, the heroic lineage intersects when Kara Kent (Supergirl) and Bruce Wayne Jr. (Robin II/Batman III) are married.
Jimmy Olsen is a unique case in the Superman cast. While most of the supporting characters are old enough that aging or deaging a few years doesn't noticeably affect how they look or their station in life, Jimmy ages between his mid to late teens where he's a "cub photographer" into his early 20s where he's usually a novice reporter and then snaps back into his late teens and being a photographer multiple times over the decades.
When Supergirl she first appeared in 1959, she was 15 (and explicitly celebrated her sixteenth birthday in 1960) and aged at a slightly slower than real time rate throughout the Silver Age. She met JFK and his wife in The Unknown Supergirl (1961), graduated high school in 1965 and graduated college in 1971, after which she became more or less 'fixed' as a young adult woman in her early 20s... until the start of the 1980s when she was inexplicably de-aged to about 19 so she could star in a college setting again.
Superman is largely averting this as of Infinite Frontier. Clark is now written as being roughly middle-aged, in his forties or fifties which fits with him being in his twenties or so at the start of Post-Crisis, and has worries about his advancing age and legacy as recurring themes hanging over his head. By extension, Supergirl is written as if she's in her early twenties at youngest and clearly isn't a teenager anymore.
As of Adventure Comics #2, the time between Superboy's death in Infinite Crisis and his return in Final Crisis (i.e. 52 + Countdown) is said to be slightly over a year.
After The Death of Superman, DC released an in-universe Newsweek equivalent that had, at one point, short quotes from various real and fictional people about Superman, his life, his death, etc. One was from William Shatner, describing how he wore a towel around his neck and jumped off his garage roof when he was six. This makes William Shatner roughly 16 in the DC universe.
Pre-Crisis, Superboy's time-era was originally shown as being either vaguely defined or taking place at the time of publication. Adventure Comics #174 (1952) shows Lana Lang competing to become "Miss Smallville of 1952" for instance. Starting in the late 50s, the writers of the Superboy (1949) and Adventure Comics books corrected this and set Superboy as taking place in The '30s (before Superman's 1938 debut date in the comics). By the late 1960s, this was clearly becoming unfeasible, and Superboy was then placed firmly on a sliding timescale 13-15 years behind the present-day Superman, moving his time-era up to The '50s and then the late 1960s / the early 1970s by the time Crisis on Infinite Earths hit. This resulted in such things as the classic story Superman (1939) #170 "Superman's Mission For President Kennedy" (July, 1964) being retold in Superboy 1980 #27 (March, 1982) as "Superboy's Mission For President Kennedy".
A 30th Anniversary special for the Return of Superman establishes that The Death of Superman and subsequent storylines occurred only a few years ago In-Universe. Four flashback stories focussing on each of the successor Supermen show people with smartphones, widespread internet access and social media; but Bill Clinton is president and everyone is dressed and talking like it's The '90s.
Harley's Black Little Book indicates that the Superman vs. Muhammad Ali crossover from the 1970's is somehow still canon, despite Ali having been retired for decades. This is even jokingly referenced in the solicitation for the issue:
(Mumble-mumble) years ago, the alien race known as the Scrubb forced Superman into a boxing match for the ages, against Earth's greatest heavyweight champion, (mumble-mumble)!
Pre-Flashpoint, Batman and Superman debuted in the same year. Circa the start of Final Crisis, Bats, Supes, and the in-universe Silver Age of Superheroes is around 13-14 years old.
In one Green Lantern storyline published during Crisis on Infinite Earths, it was speculated that John Stewart was about 12-years-old back when Abin Sur's ring first first chose Hal Jordan as Abin's successor (and Guy Gardner as Jordan's backup). This suggested that Hal had been Earth's Green Lantern for quite some time, which was further supported by the gray temples he began sporting in the 90s. This would later be supported by Kevin Smith’s Green Arrow run in 2001, which claimed that the “Hard Travelling Heroes” era where Hal and Ollie trekked across America (first published in 1970) took place a decade ago. Geoff Johns' run tried to compress Hal’s career and deage the character, even retconning his gray hair to be a sign of Parallax’s possession rather than a natural consequence of growing older. The later "Secret Origin" storyline would show that Hal and John first met back when they were both part of the military while in their early 20s, removing the implication that Hal was many years John’s senior.
The Teen Titans storyline "Titans Hunt" begins on the eve of the third anniversary of the New Teen Titans. The New Teen Titans was first launched in 1980 and "Titans Hunt" was published in 1990, meaning the team had a decade's worth of adventures in just three years.
One memorable issue of The Brave and the Bold from 1981 brought back former teen heroes Hawk and Dove, with the two now portrayed as disillusioned adults. The story suggested that the duo had aged in something approximating real world time, with Dove explicitly stated to be 27-years-old, as well as there being references to them having gotten their powers back in the late 1960s. However, due to the massive timeline problems this caused (for reference, their former teammates from the Teen Titans like Robin and Wonder Girl were still in their late teens or very early twenties at this time), the issue was later declared non-canon.
This causes some hiccups when the character's backstory is closely tied to an certain aspect of society only to have social change happen. Take Maggie Sawyer, DCU's first openly gay character: Being in her 30s when she was outed back in 1987 it made sense for her to have an angst-filled failed marriage and a daughter whose father was given full custody in her backstory. As society moves forward she then in 2012 makes references to having been pretty much out to her self her entire life and her decision to hide in a straight marriage seems quite odd. (The original story mentioned her having been raised Catholic, but no writer has run with this.) For comparison her girlfriend Kate Kane is approximately her age but was introduced in 2006 and has been out to herself her entire life without much angsting, her big thing being that she was thrown out of West Point under "Don't Ask, Don't Tell" - which will subject her to this before long (it was abolished in 2011; the 2016 film Batman: Bad Blood changed it).
In the final issue of Grant Morrison's Animal Man run, Grant Morrison breaks the fourth wall, has a conversation with the main character, and justifies Comic-Book Time by implying that, in order to get from point A to point B, a comic book character moves instantly from panel to panel instead of actually walking there, saving a lot of time.
There was also the issue where they revisited Buddy's origin. The first flashback had everyone dressing and acting like it was the 60s (when Animal Man was created), but when Buddy pointed out that the scene was not how he remembered it, the flashback then started over, now showing everyone dressing and talking like it was the 80s.
In the original Silver Age Suicide Squad stories from The Brave and the Bold, the leader of the team was Rick Flag, a World War 2 veteran. When Flag was revived for the Post-CrisisSuicide Squad relaunch decades later, he was kept young by having his WW2 backstory retroactively given to Rick Flag Sr., his newly created father.
Ignored in Hellblazer, in which John Constantine's birthday (10 May 1953) has remained static over the years and he has aged realistically, with issues being set on his 35th and 40th birthdays. Likewise, his niece has grown from a ten-year-old girl into an adult, and his friend's granddaughter has aged from a baby into a young girl. This does cause problems when he interacts with DCU characters, such as at Hal Jordan's funeral or Green Arrow and Black Canary's wedding. There is also his relationship with DCU's Zatanna — when their past dating history was established, he was only a couple of years older than her, but as he aged while Zatanna didn't, their relationship looks more and more problematic with each passing year.
This is another reason why most Vertigo stories are not considered in-continuity with the regular DC Universe. See also Exiled from Continuity.
The New 52 reboot attempts to fix this by establishing two entirely different John Constantines. The older Constantine in the Hellblazer series firmly exists outside the DCU, while a younger version exists alongside Zatanna on the Justice League Dark.
Though Hellblazer has since been cancelled and replaced by a new book called Constantine, which features the younger version.
One of the problems with the sliding timescale results in a variant of Fad Super Syndrome. In Infinite Crisis, Black Lightning claims that he chose his name because, at the time, there were very few black superheroes. Which was true enough in the seventies, but by this point, he had to have gotten his start in the nineties with the rest of the DC crew. In fifteen years or so, he'll have chosen the name Black Lightning sometime around now.
Lampshaded in Neil Gaiman's The Sandman (1989). During the Wake, we see Clark Kent, Batman, and J'onn J'onzz discussing their dreams. Clark mentions that he has a recurring dream where he gets infected with a virus that forces him to only move one direction through time.
Someone mentioned that Wonder Woman "has lived among us for nearly a decade" in a comic from 2003, nearly six decades after Wonder Woman's real world debut.
The first arc of the New 52Justice League title occurred five years ago, after which the title is set in the present day - but in the first issue after it, none of the subplots or characterisations appear to have changed at all despite five years elapsing between issues.
In Captain Carrot and His Amazing Zoo Crew!, its own extreme 80s-ness notwithstanding, an example occurs that could have been avoided had they not specifically called attention to it. The series was conceived as a Spiritual Successor to the Golden AgeFunny Animal comics DC published in the 30s and 40s, and it features characters from there in the then-present, namely Peter Porkchop and his erstwhile wolf nemesis. Yet, during a time travel arc, Fastback is transported back to World War II and meets up with his own uncle, who was also a character during that time but is now apparently very old. No explanation is given for why some characters aged and others didn't.
In Doomsday Clock, Dr. Manhattan actually views this phenomenon in action. He surmises that Comic-Book Time is actually caused by the various Crisis hitting the "Metaverse", causing comic book character histories to be pushed up by pushing up Superman's arrival. We see that the rocket originally crashed on Earth during prehistoric times, as well as future iterations of Superman, whose rocket crashed into Earth in 2016, 2038, 2045, and beyond. Manhattan summarizes that Superman is the one constant across generations, and his purpose is to lead the entire world to peace. He causes his own change by allowing Alan Scott to die before he can become the Green Lantern, which causes a ripple effect that results in the JSA having never existed. This was used to explain the lack of the JSA in the New 52 continuity, as well as why superheroes didn't start appearing en masse until the early 21st century.
The 2021 Generations miniseries appears to star characters from multiple different eras in DC’s history, i.e. the Golden Age Batman, the Silver Age Superboy, the post-Crisis Starfire and also characters from possible futures like Kamandi. It’s revealed at the end that they are all from the same universe known as the “Linearverse”, where people age extremely slowly, so the Batman who began his career in 1939 is the same Batman operating in the modern day.
Aztek: The Ultimate Man has a character named Curtis Falconer who is forced to resume his supervillain persona the Piper. He is said to have been active as the Piper in the 1960s and to have fought Elongated Man and the Atom, neither hero showing any signs of aging at the time.
by Fred Hembeck pondered the situation of Superman and Superboy having met John F. Kennedy (and posited that by the late 80s, it'd be Superbaby having met JFK) (The actual Superman (1939) #458 was released