All Creatures Great & Small (2020): Siegfried is much older than his original counterpart. Here he was in World War One, while before he'd been described by James as just a few years older than him. The Mrs Hall of the novels is also described as in her sixties, but here she's played by the 44-year-old Anna Madeley. This may have been altered to better fit actor Samuel West's age, as he's 54 (though he could pretty easily pass for a couple decades younger).
In the Animorphs book series, the characters age from 13 in book 1 to 16 in book 54. In the short-lived TV series, though, the characters start out as 15- and 16-year-olds (played by actors as old as 25). In all fairness, as part of the series' conceit that it was secret accounts of a guerilla war, the characters deliberately obscured their ages; their exact age at the beginning wasn't revealed until the second-to-last book, and the show was canceled long before then
In the definitive adaptation of Anne of Green Gables, Megan Follows, who was seventeen at the time, played an Anne Shirley who was advanced in-text from eleven to thirteen years old. Not, perhaps, a vast difference (Follows is still effective in the role), but the scatterbrained, temperamental, and openly imaginative character seems exaggerated when she's aged up.
In the comics, Roy was young enough to be adopted as Oliver's ward, like Dick Grayson to Batman. In the show, they're closer in age to the point they're more like brothers. Similarly, Mia Dearden (Thea's comic book counterpart) is a young teenager when her and Oliver first meet (around 16), and is at least a decade younger than Roy. While Roy's exact age isn't clarified in the show, she's 17/18 in the first season when the two start dating, implying he's only in his early twenties at most.
Similarly, Dinah Laurel Lance/Black Canary started her crime fighting career when she was in her late teens, and was around 19 when she joined the Justice League and first met Oliver (who was a good few years older than her). In the show, the two went to school together and are the same age. Likewise, the first Black Canary, Dinah Drake, is usually significantly older, having fought crime long before Oliver started, but in the show, Sara Lance, the show's version of the first Canary, is actually younger than Oliver and Laurel by a few years, being Laurel's younger sister instead of her mom. And Dinah Drake is the name of the third Canary, who isn't old enough to be Laurel's mother either.
In the comics, Felicity Smoak is Ronnie Raymond's stepmother, but the show first sees her at 23.
Sin in the comics is an little girl, but the series depicts her as a teenager.
Jean Loring is the same age as Moira Queen and hence older than Ray Palmer.
Ted Grant/Wildcat is usually a Badass Grandpa in the comics (post-Golden Age), while he's played by J.R. Ramirez in the show, who is in his 30s.
Cynthia Addai-Robinson, an actress in her 20s during Season 2, played the traditionally middle-aged Amanda Waller.
Lyla Michaels, a.k.a. Harbinger, is depicted in the show as an adult, as opposed to the teenager of the comics.
Deathstroke is commonly depicted as a middle-aged man with at least one adult son and a full head of white hair. Here, he's in his 40s (in the present day scenes at least). William Wintergreen, who is commonly depicted as Slade's muchOlder Sidekick is also younger, being the same age as Slade.
Comics Darhk is a young man comparable in age to several of the older Teen Titans members. In the series, he's played by 49 year old Neal McDonough — and additionally this Darhk is a peer of Ra's al Ghul.
Count Vertigo is usually a middle-aged man, but in Arrow, going by Seth Gabel's age, only in his 30s. The second Count played by Peter Stormare is closer in age.
Barry himself is a bit younger than his usual depictions, at 25 years old in season 1. This is actually turned into a plot point when it's revealed that the "Man in Yellow" turned him into the Flash seven years early, giving Barry his powers in 2013 instead of 2020.
Wally West is only a few years younger than Barry and Iris, whereas in the comics he was introduced as a young teenager while Barry and Iris were closer to 30. This fits with him being Related Differently in the Adaptation, being Iris's half-brother in the show but her nephew in the comics.
Ronnie Raymond is traditionally a teenager when he becomes the superhero Firestorm; here, he's roughly in his mid-to-late twenties. Jason Rusch is likewise a grad student in the show, not a high school student.
Girder, Peek-A-Boo, and Tar Pit are foes of Wally in the comics, but here's they're the same age as Barry and among his enemies. Girder himself in the comics is a middle-aged man.
Tokamak is an old man in the comics, but around Barry's age on the show.
Played with Griffin Grey. He is currently 18 years old but got his powers at 16, which is part of the age group he belongs to in the comics. However, he's around that age during a much earlier point in time of his existence in the comics, where he was the same age as Impulse, Barry's grandson.
Dante Ramon and Vibe are close in age in the comics, but Dante is 13 years older than Cisco in the show.
Hunter Zolomon has a few years on Barry in the show whereas his comics counterpart was a foe of Wally West and close to Wally in age. When he impersonated Jay Garrick, he seemed to be this for Jay as well, being around his 30s, but the real Jay Garrick averted this, being middle-aged.
Vandal Savage here is a Composite Character with elements of Hath-Set and having his origin tied to Hawkman's; he's only been alive since Ancient Egypt and isn't a caveman.
In the comics, Grant Wilson is Slade's eldest child. Given his apparent age in 2046 and the flashbacks on Arrow set in the late 2000s where Slade only mentions Joe, it's very likely that Joe is the older brother here. Another one of Slade's children in the comics, Rose Wilson, was fused with Isabel Rochev.
Usually depicted in her twenties or early thirties in modern times (her parents met at Woodstock according to a 1992 story), the series's Talia al Ghul would be in her sixties in 2016, assuming she didn't use the Lazarus Pit to stall her aging like Ra's and Darhk have.
Obsidian and Stargirl are both members of the original JSA during World War II, rather than second-generation members of the team. In a later episode 76-year old Lance Henriksen plays Obsidian in The '80s.
Stephanie Brown in the comics starts her career as Spoiler as a young teenager. Here she's 25 (and not a costumed vigilante at all), although her first (behind the scenes) activity in "spoiling" the Cluemaster's crimes was five years earlier.
Avatar: The Last Airbender (2024): Lieutenant Jee and the rest of Zuko's crew were in their thirties or older in the cartoon. In the series, they're all in their very early twenties, not much older than Zuko himself. There's a reason for that. It turns out that they are in fact the 41st Division, the group of recruits who were set to be sacrificed as bait in a battle. Zuko speaking up for them is what got him scarred and banished, and Ozai assigned them as his crew so that he would have a reminder of "the cost of compassion."
The Boys (2019): Jonah Vogelbaum. He's a WWII German defector in the comics, but actor John Doman was born at the end of that war.
Chiefs: In the book, Sonny is a baby the first time Chief Lee shows up to investigate a domestic violence case against Mr. Butts, while he's a Creepy Child in the show.
The Comic Bang, the Chinese live-action adaptation of Monthly Girls' Nozaki-kun, changed the main cast from high schoolers to university students. This is out of pragmaticism since the Chinese high-school curriculum is so much of a Training from Hell (discussed in that trope's Real Life section) that no Chinese viewer can reasonably believe a Chinese high-school student can have the time, effort, and/or parental support to become a professional Sequential Artist.
Deadwood is only Very Loosely Based on a True Story, so a lot about the real-life characters are rewritten. For example, Al Swearengen was a just-married 31 year-old man from Iowa in 1876, while the TV character is a single, globe-trotting Englishman in his 60s.
Many members of the main cast are decades older than their comic counterparts, with one of the more noticeable examples being Dorothy Spinner, her incarnation here being over 100 years old, albeit initially looking like an 11-year-old girl before puberty caught up with her near the end of the second season and she started gradually maturing physically, when her comic counterpart's age was initially ambiguous (to the extent that some artists, such as Erik Larsen in her debut during Paul Kupperberg's run and Glenn Fabry in her depiction on the cover to the Vertigo Jam one-shot, drew her in a way that she looked like an adult woman) before Rachel Pollack's run had Cliff imply that Dorothy was a minor in issue 68 and subsequently clarified in the recap page of issue 70note the page in question being omitted in the Omnibus collection of Rachel Pollack's run that Dorothy was 14 years old, with Dorothy most likely being at least 18 at the end of John Arcudi's run after she is Taken Off Life Support (as it was indicated there that the incident that led to Dorothy becoming comatose had occurred four years prior to the comic's events).
This continuity's version of Darren Jones appears to be decades older than his comic counterpart, who was at most in his 30s.
Dorothy has gone from the young girl in the Land of Oz books to a young adult in her early twenties.
The Wicked Witches of the East and West were depicted as old hags in the books, but are played here by 40-year-old Florence Kasumba and 31-year-old Ana Ularu respectively. However, they are also hinted to be Older Than They Look.
In Fraggle Rock, Doc was middle aged. His Back to the Rock counterpart, in addition to being a blackwoman, is in her twenties, and nicknamed Doc even though she's still working towards her doctorate.
The Fraggles themselves all have Vague Age, but Word of God is that Mokey's redesign is intended to make her "feel" younger, so she's more like one of the gang, and less like the Team Mom.
In The Gifted (2017), the Stepford Cuckoos are grown women rather than teenagers.
Going Postal: In the book, when Moist gives a man a long undelivered acceptance to his marriage proposal, it's been forty years, and he and his former sweetheart have both since been married and widowed. In the series, it's only been a few years, and the two are still in their twenties or thirties and unattached.
Gotham has some characters from Batman universe that are older then the comic book's versions:
While the Penguin is generally depicted as older than Batman, he is now apparently around Gordon's age, which makes the age difference somewhat larger.
Bullock is a little older than Gordon is. He looks the same age as his comics counterpart who reports to an older Commissioner Gordon. Likewise, Sarah Essen is older than Gordon, as opposed to being younger than him.
The Riddler, Renee Montonya, Crispus Allen, Victor Zsasz, Harvey Dent, Mario Falcone and Bane are now apparently around Gordon's age, while usually they are closer to Batman's age or younger.note In Montoya's case, this is explicit, as she turned 29 in Detective Comics #747, not long after Batman: No Man's Land, where Bruce was around 35 and Gordon's in his mid-50s Likewise, Cosmo Krank/The Toymaker, a character created for The Batman, was depicted as around Bruce's age in that show and already an adult in Gotham.
Carmine Falcone is already quite old at this point. He is played by 70-year-old John Doman, and in his first appearance, he mentions being good friends with Gordon's father. In the comics, he is around this age by the time Batman arrives.
Bruce Wayne is 12 instead of 8 when his parents die; Selina Kyle (the future Catwoman) is maybe a couple years older than him instead of youngernote Batman: Year One states Bruce is 25 at the start of the story; later stories establish that Selina was 18 at the time. Given they're regular characters with a lot of heavy dramatic material to carry, it was probably necessary to tell the story as intended here.
Matches Malone is a case of Vague Age, but in the comics, he's young enough for Batman to pull a successful Dead Person Impersonation once he believes Malone is dead and use his identity to spy on criminals. Here, he's already an adult while Bruce is a kid.
Most versions of Ra's al Ghul are around 400-700 years old. This version? Over 2,000.
One of few characters to go the other way is Leslie Thompkins - her actress Morena Baccarin was 35 when she started the role and is only about 8 months younger than Benjamin McKenzie (James Gordon), while in the comics she's depicted as a contemporary of Alfred Pennyworth (played by 50-year-old Sean Pertwee) and old friend of Thomas and Martha Wayne (the former of whom was played by 44-year old Grayson McCouch). Pennyworth himself is a case of Vague Age concerning his age relative to Bruce Wayne's, but as a whole averts this trope.
Also going in the opposite direction is Butch Gilzean, who is a case of Canon Character All Along as his real name is Cyrus Gold and in season 4, he becomes Solomon Grundy after dying. In the comics, Cyrus Gold was a man in the 19th century who died and was reanimated as Solomon Grundy around World War II, which given DC decided to keep Batman (as well as Superman, Wonder Woman, Aquaman, and Green Arrow) as peers of the Justice League, means these events happened before Bruce was even born. Here, they happen while Bruce is a teen.
The Handmaid's Tale: The Commander is older, probably middle-aged at least in the novel. In the series he's played by forty six year old Joseph Fiennes. Serena Joy is also described as being older. Here it's Yvonne Strahovski playing her, who's the same age as Elisabeth Moss, who plays Offred.
Louis de Pointe du Lac is 111 years younger on the show than in the novel; he was born in 1877 instead of 1766. Moreover, the TV character became a vampire at age 33 instead of 25; this change was made to accommodate the fact that Jacob Anderson was 31 years old during Season 1's principal photography.
In the TV adaptation, Antoinette Brown appears to be around 30 in 1917, so her birth year is in the late 1800s. Antoine was born in 1842 in the source material.
The original Claudia was born in 1789, but her TV counterpart is 114 years her junior, being born in 1903. Additionally, while her book counterpart was turned into a vampire at the age of 5, the show's version was bitten at 14, with her actress, Bailey Bass, having been 18 at the time of filming. This allowed the series to both avoid child labor restrictions (as minors are only allowed to act for a certain number of hours per day) and cast someone who could more convincingly portray a character with the mind of an adult in the body of a kid.
In the books, Dr. Fareed Bhansali was an adult when he received the Dark Gift in 1986, whereas his TV iteration is in his mid-to-late 30s in 2022, so the latter was born in the mid-1980s.
Although Lestat de Lioncourt's birth month and year are the same on the show as it is in the novels, what is different in the TV adaptation is that he was transformed into a vampire at age 33-34 (depending on the month) instead of 20 like in the source material. Sam Reid was 34 years old during Season 1's principal photography.
In the series, Armand is 28 years younger than the book character, as his birth year is 1508 instead of 1480. He's physically 17 in the novels, but stated to be in his 20s on the show.
Jesse Stone: Jesse is in his mid-thirties in the novel series, while in the TV movies he's played by Tom Selleck, who's in his 60s. Despite this Robert B. Parker himself approved and said Selleck nailed the role.
In the TV series of Kim's Convenience Janet is 20 and still in college; in the play the show is based on, she's 30 years old, already graduated and is working as a professional photographer. Jung is 24 in the show while in the play he's 32 (and even has a wife and kid). Justified as while a lot of stories from the play have been adapted, the timeline of the show is about a decade before the timeline of the play.
Let the Right One In: Eli in the book has been alive for hundreds of years. In the series, she has only been a vampire for ten.
Donnie Gill, an adult in the comics, is depicted as an 18-year-old S.H.I.E.L.D. cadet.
There's Eric Koenig and his "brothers". In the comics, Koenig is a veteran of World War II and would have to at least be in his 80s, while in the show, he and his brothers are played by 46-year-old Patton Oswalt.
Jeffrey Mace in the comics was one of the men who filled in for Steve Rogers as Captain America when he was still in ice. Here, he's played by 44-year old Jason O'Mara and is a present day character, replacing Coulson as the head of S.H.I.E.L.D. once it once again becomes an official agency.
Agent Carter is set not long after World War II and features Whitney Frost, Joseph Manfredi, and Roger Dooley—all three being present day characters, with Dooley notoriously having sexually harassed She-Hulk, Frost being the supervillainess Madame Masque and a frequent enemy of Iron Man, and Mandfredi likewise being the supervillain Blackwing and having fought Captain America and Daredevil (and his father being the Spider-Man villain Silvermane).
Daredevil (2015): Leland Owlsley, who is usually middle-aged in the comics, is played by a 70 year old Bob Gunton. However, Leland also says several times throughout season 1 that he has a son named Lee (who'd probably be the right age). That, combined with Leland never getting to be the Owl because of Wilson Fisk killing him in the season 1 finale, strongly suggests this to actually be a case of Decomposite Character in play.
Jessica Jones (2015): In the comics, Jessica Jones and Peter Parker were in high school together when the latter started his career as Spider-Man, but because the TV show was written before Spider-Man joined the MCU (and before anyone working on the show had any idea how he would be integrated), Jessica is a grown woman when Peter is only 15. Somewhat moot in that Spider-Man doesn't actually appear on the show, though.
Iron Fist (2017): Ward Meachum is in his fifties in the comics and is Harold Meachum's brother and Joy Meachum's uncle. In the show, he's played by a 35 year old Tom Pelphrey, and is now Harold's son and Joy's brother.
In Runaways, Molly starts off as an 11-year-old who may or may not be starting puberty in the first issue. In the TV adaptation, she's played by 15-year-old Allegra Acosta. She's still The Baby of the Bunch, but it's not as obvious.
WandaVision: In the comics, Agatha Harkness is old enough to have been alive during the sinking of Atlantis thousands of years ago, and is usually depicted as an old woman with gray hair and wrinkles. Her MCU counterpart was apparently born in the 1600s, and physically looks to be in her 40s at the absolute oldest.
The Falcon and the Winter Soldier has the gender swapped Flag Smasher aka Karli Morgenthau played Erin Kellyman who was in her early 20s at time of filming. In the comics Karl Morgenthau is a grown man.
The series cast the 52 year old Owen Wilson as Mobius M. Mobius who appears to be well past his prime (though he doesn’t age) in the comics. Although Wilson’s Mobius has grey hair while the comic version has (receding) brown hair.
Played with regarding He Who Remains. In the comics, he's ancient, and has an emaciated, almost skeletal appearance. Here, due to being made into a Composite Character with Immortus, he physically appears to be in his 30s at the absolute oldest. However, he explicitly claims to be Older Than He Looks, having been alive long enough to predate the current Sacred Timeline.
In the comics, Kate Bishop was still in high school when she first became a costumed superhero. In Hawkeye (2021), she's 22 in the first season.
Constance Contraire from The Mysterious Benedict Society. In the first book, Constance is only two years old, but is incredibly gifted for her age and is able to read, write, and speak at the level of a typical nine-year old. Due to the impracticalities of finding someone who could feasibly play that, the show cast ten-year old Marta Kessler and completely changed her backstory.
Once Upon a Time does this with a few fairy tale and Disney characters:
Ariel was sixteen in her film. Here she is at least late twenties-early thirties.
Snow White (as noted above) is seven in the original tale and fourteen in the Disney film. She's in her twenties.
Peter Pan is eternally five or six in the novel (he's said to still have his baby teeth). His actor Robbie Kaye was seventeen at the time of filming. What's more is that he's really a man in his (physical) 40s de-aged by magic.
Red Riding Hood is often written as a preteen. Here she is around 18-21.
Cinderella's Fairy Godmother is portrayed as an elderly woman in the Disney film. Her brief appearance has her significantly younger.
The Mad Hatter is often portrayed as an elderly man. Here he's in his 20s.
The Wizard of Oz is an older man too but is played by a younger actor.
Although a minor character, the Good Witch of the North is an older woman. She's played by a young actress.
The title character is thirteen (sort of; Mental Time Travel is involved so she's older than she looks) and Min De is eight. In The Princess Wei Young they're both adults.
Historically Tuoba Jun was only twelve when he became emperor. He's an adult in both the novel and the series.
Poldark: Demelza is 13 at the start of the first book, and she seems to be closer to 17 in the show, which is good as she has sex with Ross in episode 3.
A good many of the team in Super Sentai are composed of full-grown adults, whereas their American adaptations, Power Rangers will often (but not always, age them down to teenagers. Granted, there's a few cases of Power Rangers aging team members up (Tsuruhime was indeed was a teenager in her home series, while Delphine was an adult like the others Aquitar Rangers, and thanks to being a Composite Character of several Sentai characters, Tommy Oliver, even as a teenager, was older than Kou, who was a little kid).
Queen for Seven Days: Historically Chae-gyeong and Lee Yeok got married when she was thirteen and he was twelve. For obvious reasons the series makes them both adults.
Roswell, New Mexico changes the high schoolers from Roswell High and the first adaptation, Roswell to adults in their late twenties. It's explicitly stated that at least a decade has passed since their high school graduation.
Salem: Massively done with John Alden. The real man was born in 1626/1627, which would make him around 66 years old at the time of the witch trials, while in the show he's played by Shane West, a man in his 30s.
The Sandman (2022): In this show, Unity Kincaid is 12 years old when she falls victim to the sleeping sickness instead of 19 years old as is the case in the original comic book series.
Clary Fray turned 16 2/3rds of the way through City of Bones, here she starts off the series celebrating her 18th birthday.
Simon Lewis was 17 in the books, but says he's 18 in the fourth episode.
Jace Wayland is 17 in the book, but in his early twenties 20s in the show.
Madame Dorothea was an old woman in City of Bones, but in the show her counterpart Dot is only in her thirties.
Maureen Brown is 14 (but looks about 12) in the books, but on the show she's around the same age as Clary and Simon, who are already older than their book counterparts.
In Sherlock, Professor James Moriarty, the elderly, doddering math teacher, becomes the young, suave, snappy-dressing career criminal Jim Moriarty. Tellingly, where the literary Moriarty assumed the cover identity of a university professor to keep his reputation clean, the series' version does the same thing by crafting a cover identity as a television actor.
Smallville: Kara is 15 in her comic book debut as Supergirl, but is around 19 when she first appears in the show.
The Spanish Princess: Catherine of Aragon, Prince Arthur, and Prince Henry have all been aged up at least a decade for the show here, probably because teenagers in an arranged marriage isn't going to go over well with their modern audiences.
When they first debuted in Infinity, Inc., Yolanda Montez (Wildcat II), Beth Chapel (Doctor Mid-Nite II) and Rick Tyler (Hourman II) were all young adults in their early 20s, with Beth being a medical intern and Yolanda having a job as a reporter for a rock magazine. In the TV show, they're all teenagers who attend the same high school as Courtney, who is much younger than them in the comics.
Odd example with Starman and Stripsey. In the original comics, Sylvester Pemberton was 61 years old when he died, but had the body of a young man in his early 20sdue to having been lost in time for several decades. His partner Pat Dugan was even older, albeit with the same slowed aging applied. The TV show moves Pemberton and Dugan's origins as the Star-Spangled Kid and Stripsey from the early 1940s to sometime in The '90s and ditches the time lost aspect entirely, meaning they were in their 30s when Pemberton died. The show also lessens the age gap between the two, with Pat mentioning that he was 20 when he first met the 15-year-old Sylvester. This is in contrast to the original Golden Age comics, where Pat always looked significantly older than Sylvester.
This seems to be the case for most of the JSA in general. In the original comics, the JSA was formed in the 1940s, with many of its surviving members remaining supernaturally young for one reason or another. The TV show is vague about when exactly the JSA was formed, but most of its members were played by actors in their 30s-to-late-40s in the flashback scenes set 10 years in the past. This also applies to their enemies, the Injustice Society.
Kara is usually in her teens when she becomes Supergirl (she was 15 when she first debuted in the comics), but on the show, she starts out at the age of 24. This prompted an in-universe discussion about why a grown adult would call herself Supergirl and not Superwoman.
Likewise, in both the comics and Young Justice, Miss Martian was a teenager, and even attended high school in her Megan Morse identity. In the live-action show, Megan is in her 20s and works as a bartender.
Lady Silence from The Terror is a teenager in the book that the programme is adapted from. Her TV version is a woman apparently in her late thirties or early forties, one of several changes made to pad out the character’s agency and narrative growth and to change her from being an exoticised love interest for the series’ cast of white men.
Dick Grayson was in his late teens when the New Teen Titans were formed in the comics. In the first season of the show, he's in his late 20s and already has a career as a police detective before the new Titans come together.
Likewise, Donna Troy was established as being roughly around Dick's age in the comics. She's slightly older than him (but still young enough to have been his contemporary in the original Titans) in the show, which would also put her in her late 20s.
The same applies to Hawk and Dove, who were also part of the original Titans alongside Dick and Donna.
Raven was 18 when she was first introduced in the comics, and eventually began attending college. Here, she's 14.
In the comics, Jason Todd was still a minor when he became the new Robin. He's explicitly said to be 19 when he makes his debut in the show.
Thanks to Comic-Book Time, Bruce Wayne is usually depicted in his late 30s/early 40s at the absolute oldest in the mainline comics. In the TV show, he's played by Ian Glen, who was in his late 50s at the time of filming.
Wintergreen, who is usually Deathstroke's senior, is now younger than him, and even playfully refers to him as "Old man."
Likewise, in the comics, Leslie Thompkins is an elderly woman who comforted a young Bruce Wayne on the night his parents were killed. This version of Leslie is played by Krista Bridges, who was in her very early 50s at the time of filming, presumably making her younger than Bruce. Jason even wonders if the two were lovers in the past.
Like Jason, Tim Drake is in his late teens when he becomes the new Robin, unlike in the comics, where he was 14.
Lex Luthor is stated to be 67, quite a bit older than he's usually depicted in the comics. Nightwing also claims that Lex spent 40 years trying to kill Superman, likely indicating that Superman is at least middle-aged in this universe.
True Blood, the TV adaptation of The Sookie Stackhouse Mysteries, casts the fortysomething actress Kristen Bauer von Straten as Pam, who was turned into a vampire at age 19 in the books. The show also gives her the backstory of being a madam of a brothel, an occupation traditionally for an older woman.
Anthony Fremont from "It's a Good Life" was aged up from three years old to six for the television adaptation, as a toddler couldn't have been relied on to act a part or been given any lines.
In the 1967 short story "A Message from Charity" by William M. Lee, Charity Payne is 11 years old in 1700 when she begins communicating with the 16-year-old Peter Wood in the present. In the adaptation, she is several years older. Although her age is not stated, she is seemingly closer to Peter's age. This change was made because the episode places more emphasis on Charity and Peter being each other's first love than the original story. There is also the scene in which Squire Jonas Hacker attempts to rape Charity after claiming that she needed to disrobe so that he could check her for the mark of a witch, which is toned down in the episode compared to the short story. She manages to fight him off in both versions.
The Umbrella Academy (2019) does this to Five, a.k.a., The Boy. In the comic he was 10 years old when he travelled through time to the Bad Future where he grows into a sixty-year-old man; due to a miscalculation he gets stuck permanently in his 10-year-old self's body. In the show, Five is played by Aidan Gallagher, who was 16 at time of filming.
The Wheel of Time (2021): Egwene has been aged up compared to her book counterpart, where she was younger than Rand by a few years. Downplayed for Mat, Rand and Perrin: their age is the same as in the books (19-20, as established by the dates given in the glossaries of the books) but they are also portrayed as far more mature than in the books, including Perrin already being married.
The girls in the books were around eleven or twelve but appear to be around sixteen by the third season of the TV series. So notable that the fourth season was changed to a college setting because it would have no longer be believable that Mildred would still be at school.
Miss Drill was also a strict older woman like the rest of the teachers in the books. In the TV series she is a much younger woman. This is addressed in-universe as Miss Drill is frequently at odds with the traditional older teachers.
The premise of Younger is essentially giving Liza an In-Universe Age Lift, de-aging her with the help of fashion and Internet scrubbing in order to make her appear age-appropriate for her new career.
In the webtoon Yumi's Cells, Daeyong first met Yumi when he was a freshman in college; they were the same age. In the adaptation, Daeyong was a graduate student at the time, making him several years her seonbae.
In the manga, Koenma was a centuries old god with the body of a baby, though he would eventually transform into a teen/young adult in later arcs. The live-action show depicts him with an adult body from the start, presumably due to the challenges that using an actual child actor would have posed.
was born in 1626/1627, which would make him around 66 years old at the time of the witch trials, while in the show he's played by Shane West, a man in his 30s.