If an adaptation of a series is popular, it will leave its stamp on subsequent adaptations. More strangely, a popular adaptation may leave its stamp on the series it was adapted from, if that series is still ongoing. Ret-Canon is when elements from an adaptation of a work (or the adaptation as a whole) is later made canonical due to the source material acknowledging it or Word of God stating it as such.
For the more general application of changes to the work, see Retcon.
The Canon Immigrant is often a walking example of Ret-Canon. See also: Recursive Adaptation, Adaptation Displacement, and Canon Discontinuity.
Compare Ascended Fanon, where it's Fanon that becomes canonical instead of adaptation-only material.
Example subpages:
Other examples:
- G.I. Joe: The Rise of Cobra recast Ripcord (formerly a redheaded white guy) as black. Since then, Ripcord has been introduced in three new continuities—the IDW comicbooks, G.I. Joe: Resolute and the G.I. Joe: Renegades cartoon—and in all three of them he's a young black man.
- In order to manage the many characters in Arthurian legend, John Boorman's Excalibur merged the characters of Morgause of Orkney and Morgana le Fay into one Composite Character, keeping the latter's name and powers of sorcery, but giving her the former's role of mothering Mordred after an incestuous affair with Arthur. Though he may not have been the first to make this change, his film popularized the incestuous angle between Morgana and Arthur in many adaptations to come.
- The Lion King:
- "The Morning Report" was written for the theatrical adaptation but later animated and added into the IMAX re-release of the movie (with different voices).
- "He Lives In You" from The Lion King II: Simba's Pride is from a CD for the original film that was later added into the theatrical play. The film version is more well-known. The context was changed between the versions. The theater version is sung by Rafiki to Simba during the part where Simba speaks to Mufasa while the film version happens during Kiara's (Simba's daughter) presentation and is sung by an outside source.
- A map in Star Trek Into Darkness shows the Klingon homeworld, Kronos/Qo'noS, to be located in the "Omega Leonis sector block". The "sector block" descriptor is a cartography term created by the Star Trek Star Charts licensed reference book by Geoffrey Mandel, and the Omega Leonis sector block nomenclature was created for Star Trek Online's overworld. (Sector blocks have since been removed from the game in favor of rendering the entire quadrant as a single map.)
- Power Rangers and Super Sentai:
- Mighty Morphin' Power Rangers originally had Zordon existing in a limbo dimension, with the tube he spoke out of being only his form of communication. Mighty Morphin Power Rangers: The Movie had Zordon being physically in the tube in a pocket dimension and capable of being killed by rupturing that tube. In Power Rangers Turbo (about two years after the first movie) Zordon was magically brought to the physical tube in a pocket dimension, allowing him to return to his homeworld and exist in a state similar to the movie, and in fact became a major plot element of Power Rangers in Space where Zordon is captured.
- Speaking of homeworld, Power Rangers: The Movie had Lord Zedd acknowledge that Zordon's home planet is Eltar, something that was never mentioned in the show. Since then, Eltar was mentioned in a few post-MMPR seasons. Though this was in the Universe Bible, so it's more that the movie was just the first to say it out loud.
- Power Rangers RPM introduced a special move using the wheels from the Rangers' suits, an attack which didn't exist in Engine Sentai Go-onger. The move was later incorporated into the Super Sentai canon in Kaizoku Sentai Gokaiger.
- When the TyrannoRanger from Kyōryū Sentai Zyuranger showed up in the Kyoryuger vs Go-Busters movie, he was given a modernized Transformation Sequence based off the one Adam Park used during his guest spot on Power Rangers Operation Overdrive. They even used the Legacy Power Morpher toy that Bandai had released for the 20th anniversary of Power Rangers for the transformation scene!
- Red Dwarf:
- As of Series IV, Lister's backstory with Kochanski was retconned to one closer to what appeared in the novel Red Dwarf: Infinity Welcomes Careful Drivers and Red Dwarf USA than had been detailed in the first two series. Originally he'd been hopelessly in love with her, but never had the nerve to ask her out ("In your entire life, your conversations with her totalled 123 words. You had a better relationship with your rubber plant"); in the books they dated for a while, then she got back with "Tim, or Tom, or it may have been Tony" from Catering. The breakup first gets mentioned on screen in the Season IV episode "DNA", and Tim is referenced in Season VII's "Ouroboros" and Season VIII's "Krytie TV".
- Also, Kochanski's first name was originally "Christine" as indicated by her hologram box ("KOCHANSKI C.Z."). The books named her "Kristine" which the series eventually went with.
- One episode of that series was adapted from a section of a novel, rather than the other way around: the episode "White Hole" is based on the "Garbage World" section of the novel "Better Than Life". This includes the return of Talkie Toaster, who in his Season I appearances would occasionally nag Lister to eat toast, but could talk about other things, and even dreamed of "something more, something greater, something unimaginably more splendid than heating bread". In the book he was given a monomaniacal obsession with toast that carried over into this episode and his much later appearance in "Mechocracy".
- Also in "Ouroboros", Kryten says he always ends up alone, like on the Nova 5 and Lister responds "You killed the crew! All right, it was an accident, but still..." This refers to Kryten's expanded backstory in Infinity Welcomes Careful Drivers, where the Nova 5 crashed because he decided to clean the navigation computer with soapy water.
- Series IV's "Justice" states that Lister and Rimmer worked a shift called "Z-Shift". While them being the two lowest-ranked members of the crew had already been established, Z-Shift specifically originated in the books.
- As of Series IV, Lister's backstory with Kochanski was retconned to one closer to what appeared in the novel Red Dwarf: Infinity Welcomes Careful Drivers and Red Dwarf USA than had been detailed in the first two series. Originally he'd been hopelessly in love with her, but never had the nerve to ask her out ("In your entire life, your conversations with her totalled 123 words. You had a better relationship with your rubber plant"); in the books they dated for a while, then she got back with "Tim, or Tom, or it may have been Tony" from Catering. The breakup first gets mentioned on screen in the Season IV episode "DNA", and Tim is referenced in Season VII's "Ouroboros" and Season VIII's "Krytie TV".
- Smallville
- Season 7 gave us a one-off immortal villain, and clear Expy of Vandal Savage, who went by the alias "Curtis Knox". When Vandal Savage became the Big Bad of the first season of Legends of Tomorrow, one episode had him using the alias "Dr. Curtis Knox".
- Season 9 introduced an Expy of the Green Arrow foe Merlyn known as Vordigan the Dark Archer. When Merlyn was brought into Arrow, Malcolm Merlyn became his real name (his real name in the comics is Arthur King), while his codename was changed to the Dark Archer.
- Kato in The Green Hornet is now always a martial artist.
- Doctor Who:
- Various TV Dalek stories sometimes incorporated elements from the Dalek comic books and annuals, as well as the Amicus Dr. Who movies. The Emperor Dalek from "The Evil of the Daleks" is a Canon Immigrant from The Dalek Book, from which the word "rels" in New Who also originates. "The Parting of the Ways" uses Dalek spaceships modelled after the comic book ones, and even shows a Dalek with a movie-style claw attachment in place of a plunger at one point (although it is a flamethrower).
- "The Power of the Doctor", without giving details, suggests that Ace stopped travelling with the Seventh Doctor after a serious moral disagreement between them that she later regretted, reflecting her initial break with him in the Doctor Who New Adventures novel series continuity.
- After UB40 hit the top of the charts with a reworked reggae version of Neil Diamond's "Red Red Wine", Diamond began performing their version of the song in concert.
- UB40's version was based on Tony Tribe's 1971 reggae reworking of the song, but evidently that hadn't been popular enough to justify Diamond changing his arrangement.
- Johnny Cash's version of Nine Inch Nails' Hurt. Trent Reznor himself even said:
It feels like I've just lost a girlfriend, because that song isn't mine anymore.
- Bob Dylan in concert tends to perform Jimi Hendrix's cover of his song "All Along the Watchtower".
- Billy Joel likes Garth Brooks' version of Shameless so much that he lets Garth come out and sing it when he gives a concert.
- Noel Gallagher of Oasis went through a phase of doing Ryan Adams' cover of "Wonderwall", most notably on his solo and acoustic tours.
- Suicidal Tendencies brought in significant funk influences from their side project, Infectious Grooves.
- Robert Smith, singer and guitarist for The Cure, enjoyed Dinosaur Jr.'s cover of "Just Like Heaven" so much that it has drastically influenced the way that The Cure play the song in concerts.
- Humorous example: After "Weird Al" Yankovic parodied Madonna's "Like a Virgin" music video with his own "Like a Surgeon", Madonna appeared in a second video dressed as a surgeon.
- Warhammer 40,000:
- The game didn't even have two-handed Thunder Hammers before Dawn of War gave one to its Force Commander. It was not available for a power armoured character until the 5th edition Space Marine codex, which came out after Dawn of War.
- The Tau Railrifle was first introduced in the Fire Warrior game, and was given rules as a White Dwarf supplement before being added to the next codex.
- Pathfinder: The Player Party in the 2018 Pathfinder: Kingmaker video game, adapted from the Kingmaker Adventure Path tabletop campaign by Owlcat Games, included two characters from the tabletop game (Amiri and Jubilost Narthropple) and eleven original characters. In 2022, Paizo released an add-on for the Second Edition remake of the Kingmaker Adventure Path, the Kingmaker Companion Guide, which adapted Owlcat's implementation of all thirteen characters back into tabletop format, along with personal sidequests for seven of them. The Kingmaker Bestiary re-stats them for First Edition.
- Revivals of a musical with a successful movie version will often try to find places to add songs written for the movie back into the show. E.g. Cabaret, The Sound of Music, Grease.
- Additionally, some stagings of Grease will use T-Birds, rather than Burger Palace Boys, as the name of the boys' gang.
- Revivals of Anything Goes invariably include "It's De-Lovely," "Friendship" and other Cole Porter songs originally written for other shows.
- The licensed version of The Wizard of Oz as a stage musical still has ruby slippers, while the originals were silver.
- Richard O'Brien revised the script for The Rocky Horror Show in 1990 and incorporated a few changes made for the film. Notably, "Time Warp" was moved before "Sweet Transvestite", and "Charles Atlas Song" was replaced by "I Can Make You a Man".
- After the Pirates of the Caribbean movies became popular, references to the characters were added to the original Disney World ride, along with several animatronic appearances of Captain Jack Sparrow. The latter are particularly jarring, as all of the original characters are cartoony caricatures of human beings, but Jack is a perfect likeness of Johnny Depp's character (although Depp himself may be sufficiently cartoony to justify this). More jarring is the sound. Jack Sparrow and redone sound clips mentioning him sound very clear, while any audio still from the original version of the attraction is far scratchier.
- Transformers:
- The idea that Jetfire wears a helmet/battle mask resembling his G1 toy design was first introduced by Dreamwave's Transformers: Generation One comic book, and has since been used for subsequent G1-style Jetfire action figures.
- Transformers: Animated has a group called the Cybertron Elite Guard serving as the commanding military and security force for the Autobots. Then, the BotCon 2009 theme was about a similar group (with the same winged Autobot insignias) set in G1 continuity called the Cybertronian Elite Guard. The Elite Guard are also in Prime, with Smokescreen having once been a member.
- In another Transformers example, the Beast Wars toyline originally portrayed the events as taking place on present day Earth and Optimus Primal and Megatron being merely new forms of Optimus Prime and the original Megatron. When the animated series premiered with the events taking place on prehistoric Earth via time travel and Primal and Beast Megatron being made legacy characters, the toyline was changed to match up with the cartoon.
- Transformers: Prime shows heavy influence from the Transformers Film Series, including the general appearance of Optimus Prime, Bumblebee and Megatron, as well as Bumblebee's muteness (although he now speaks in generic beeps and tones instead of talking using clips from his radio). Many fans have described the aesthetics of the robots as a mix of Movie-style and Animated-style.
- The War for Cybertron game was effectively a G1 prequel, stated to be in the same universe as the Prime series by the toy company despite the existence of Dark Energon being the only thing the two stories had in common. However, the sequel, Fall of Cybertron, is upping the similarities to Prime with Cliffjumper's head design changing from a G1-inspired design to a clearly Prime-inspired on as well as Bumblebee having his voice box destroyed by Megatron, muting him in the same way as in the Films and Prime. Prime has also had a few nods to the games. Both versions have left their marks on each other to the point that they've sorta converged.
- Prime also follows in the footsteps of Exodus lately, incorporating bits from across franchise history. Four key macguffins that go into an "Omega Lock"?
- Beast Wars introduced the concept of a robot soul called a Spark, all subsequent material have included this as a major component of the Transformer culture. This was even retroactively applied to all G1 characters, with the original Optimus Prime and Megatron having particularly powerful sparks able to upgrade the forms of Optimus Primal and Beast Wars Megatron.
- An earlier concept of this was hinted at in Generation One, when two episodes referred to a "laser core." Once, the 'cons wanted to make sure Prime's was extinguished rather than assuming he was dead due to the damage he'd taken earlier; another time, Megs ordered Devastator to extinguish the Autobots' laser cores forever. This was very spark-esque (something in your chest that, if "extinguished," means you're dead-dead and not cartoon dead, and checking for this is the only way to be sure) and may have been in the back of the Beast Wars writers' minds. However, there's no clear indication that they were aware of it when they conceived of the 'Spark' concept, and it was mentioned on those two occasions only. Since then, most canons mentioning laser cores combined them with the spark concept, stating the laser core was what the spark was housed in.
- They also introduced Protoforms, though what they are can vary from the equivalent young, infant, or even prenatal Cybertronians, to simply a Cybertronians' basic form. (The movie toy packaging stands alone in using "Protoform" to mean "Cybertronian who hasn't scanned an Earth mode yet," which would make the entire casts of The War Within or War for Cybertron protoforms.) Not every series included them, but a lot did.
- IDW Publishing's Transformers series begins life as an updated retelling of G1, but bits of other versions begin to sneak in. These days, not using things like the units of time (cycle, megacycle, etc.) and what we know of Transformer biology (sparks, etc.) that Beast Wars originated is unheard of. Also, by now, we've met Lockdown (Animated-original) and Grindcore (Movie comics original), quite a few characters from the Japan-only G1 sequels, and Omega Supreme uses his name as a Badass Boast (Animated Omega was the first to do that.)
- To make a long story short, once any Transformers property introduces a character or concept, it becomes fair game for both new series and new versions of older series. In The Multiverse, one Demolishor or Barricade or Omega Lock existing means that every universe probably has one that you just haven't met... yet.
- The use of the term "Titans" to describe massive, city-sized Transformers like Metroplex, Scorponok and Fortress Maxmimus originated in the IDW comics. It's since been officially adopted as the classification for such characters from Hasbro, featuring most prominently in 2016 Titans Return toy line.
- The movies introduce the idea of Megatron and Optimus Prime being brothers-in-arms before the former fell into villainy, and the Megatron of Transformers Prime was a dissatisfied gladiator who sought to put an end to the Cybertronian caste system until Megatron's anger and jealousy consumed him and he fell out with Optimus. These aspects of his backstory would become a common occurance across Transformers material from the 2010s onward, such as Transformers: Cyberverse and Transformers: War for Cybertron Trilogy.
- In the NES DuckTales video game, Scrooge McDuck can breathe on the moon with no explanation. In the 2013 remake, it is handwaved that Gyro Gearloose invented Oxy-chew taffy to allow users to breathe on the moon without a space suit. In the 2017 reboot, Oxy-chew appears, explaining how Della Duck stayed for so many years on the moon.
- The Moon Stage Theme from the NES video game was used in the 2017 cartoon, with added lyrics and sang by Della Duck.
- The chapter books and comics based on My Little Pony: Friendship Is Magic were initially considered Loose Canon. With Hasbro's official position that if something happened in the official comics, the official chapter books, or even in Equestria Girls, it's canonical unless outright contradicted by the series itself. Despite the fact that no episodes prior to Season 5 (save for at least one episode) make outright references to either. Several episodes in Season 5, however, either explicitly reference or allude to events in the books, largely due to the books' main writer joining the show's writing stable.
- The Series 9 finale name-drops King Vorak, Tirek's father from the comics, making him canonical to the show.
- Ninjago: Season 8 came out after The LEGO Ninjago Movie, and implements several touches from the film: the ninja's faces and hairstyles now resemble those of their movie counterparts, their uniforms are more personalized and distinct (such as Cole's lack of sleeves and Nya's armored skirt), and the Asian-style ciphers are prominently on display. The Destiny's Bounty (the team's flying Cool Boat Home Base) is also redesigned to match its movie counterpart.
- PJ Masks: The show is adapted from a series of French children's books, but drastically changed the tone from fantastic stories to a more traditional heroes vs. villains superhero show. It also added several new elements, like the heroes having their own vehicles, new villains like Night Ninja and Luna Girl and the fact one of the hero is a girl. While the overall tone of the books has remained the same, these changes were nonetheless incorporated into the books after the show became a success.
- Inspector Gadget: When the first live-action film had a talking Gadgetmobile with a hip and fun attitude, it was well-liked that they kept his traits into the cartoon after 1999.
- The Transformers: The third season featured a flashback to Cybertron's pre-history, revealing that an unidentified Autobot leader helped to defeat the Decepticons in their first war before he was killed by Megatron, leaving the Matrix of Leadership in Alpha Trion's hands before he passed it on to Optimus Prime. Around the same time, the Marvel Comic identified Optimus' predecessor as "Sentinel Prime," but only in its pages. By the 2010s, Sentinel had gone on to greater prominence in Transformers media, notably as both an an authoritative jerk, and a villain, so Hasbro deemed the previously unidentified Autobot leader from the cartoon as its version of Sentinel.