When a work is being adapted, liberties with the original will have to be made. Due to time or length constraints, some things may have to be taken out. Someone being Adapted Out involves taking a character who was fairly important in the original story and cutting them out.
Could happen because of Adaptation Distillation, in a Compressed Adaptation or a Pragmatic Adaptation. These characters would usually fall victim to the existence of a Composite Character, with which there is often plenty of overlap.
Related to Chuck Cunningham Syndrome where a character vanishes without explanation from the original work.
Examples are listed in the original format of the media being adapted from as opposed to the medium they are being adapted to.
Anime and Manga
Midori Days: The anime version is only 13 episodes long, whereas the manga is 85 chapters in all. Because of the difference in length, characters like Nao and her father, Shirou, were left out of the anime, along with Lucy, who's an expy of Tiffany Lords.
One cartoon adaptation of the Fantastic Four entirely dispensed with Johnny Storm aka The Human Torch, and substituted Herbie the Robot.
Gwen Stacy from Spider-man is absent in the first two movies and the 1994 animated series (save for one appearance in an Alternate Universe).
The BBC's radio adaptation of Tintin adventures Destination Moon and Explorers On The Moon omit Thomson and Thompson. Consequently, Jorgen is solely responsible for the oxygen being used up too fast on the rocket.
The character of Mort (one of Basin City's few honest cops) was written out of the cinema version of Sin City. In the comics, Mort is the own who picks Hartigan up outside the prison. In the movie, this was done by Bob. (The extended version still includes a scene where Mort visits Hartigan in hospital.)
Likewise, the real creator of the Hulk, commie spy Igor Drenkov - who Banner told to stop the countdown but didn't - doesn't appear in adaptations with the exception of The Marvel Superheroes, a Motion Comic which used the original comic book panels.
The character of Lisa Miller is absent from the film adaptation of Scott Pilgrim, although she does appear in the animated short.
The giant squid monster is removed, yet the backstory about its creation still seems to exist.
Bernard and Bernie, the newspaper seller and the kid who hangs around his stand, don't appear except during the big explosion which wipes them out, making you wonder who they are. The rest of the cast of their B-plot don't even show up that much.
Carl the friar is absent in the tie-in videogame adaption of Van Helsing. So is Chas Kramer from the Constantine tie-in game.
When The Producers was adapted into a stage musical of the same name, Lorenzo St. DuBois, a hippie nicknamed LSD, was given this treatment. In the original film, he walks into the Springtime for Hitler auditions by mistake and is chosen to play Hitler by virtue of his utter lack of talent. LSD's So Bad, It's Good performance as Hitler plays a large role in the play's unintentional and unwanted success. In the musical, Franz Liebkind is chosen to play Hitler, but Roger De Bris is the one to perform the role onstage after Franz breaks his leg.
Numerous characters in the film versions of Harry Potter. Some do not appear at all (such as Peeves the poltergeist), some are absent in earlier films, but show up later when they're important with an explanation as to why they've been absent (such as Bill and Charlie Weasely) and some appear in earlier films but are absent in later ones (such as Dobby, Nearly Headless Nick and Firenze).
Glorfindel is absent in both adaptations, too. In the Peter Jackson films, his role of rescuing Frodo from the Nazgul and bringing him to Rivendell is given to Arwen. In Bakshi's adaptation, his role is given to Legolas. Similarly, Prince Imrahil who plays a major role in The Return of the King is omitted entirely from both the Peter Jackson films, and the Rankin/Bass versions. In the books his role supporting Gandalf's defense of Minas Tirith and his support of Aragorn as King of Gondor are fairly important plot points, as he's the one that figures Aragorn can cure victims of the Nazgul.
Goldberry, Ghan-buri-Ghan, Quickbeam the Ent, Elrond's sons Elladan and Elrohir are also absent from the Peter Jackson film.
Madge Undersee and her family do not appear in the film versions of The Hunger Games probably due to casting logistics and length constraints. Instead, her role of giving the mockingjay pin to Katniss is given to a vendor.
The Warrior Cats graphic novel trilogy SkyClan and the Stranger (and bonus manga at the end of SkyClan's Destiny) is unique among Warriors mangas in that they try to make all SkyClan cats appear, or at least be mentioned. While almost the entire Clan is in there, the only ones to not show up or be mentioned at all in either the trilogy or the bonus manga are Sagepaw and Egg, for whatever reason.
Disney's Alice in Wonderland adaptation leaves out the Duchess, Fish Footman, the Frogman, the cook, the pig baby, the Gryphon and the Mock Turtle (although sequences were storyboarded for the deleted characters). The latter two characters were dropped for being "too talkative" (or words to that effect). Earlier drafts omitted Alice's sister.
Jan Svankmajer's Alice omits the Cheshire Cat and replaces the Duchess's role with the White Rabbit.
Gor, the film version of Tarnsman of Gor, adapts out Tarl's father Matthew, the Older Tarl (Tarl's instructor at arms), Torm the Scribe, Tarl's sword brother Kazrak of Port Kar, the slave girl Sana, Nor the (sentient) spider, Pa-Kur the Master Assassin, Mintar the Merchant, and Tarl's tarn Ubar of the Skies.
Dirk, the stage adaptation of Dirk Gently's Holistic Detective Agency, drops the Monk and his horse, partly to simplify the timeline of events (in the novel, the Monk spends most of the story off on his own doing things that only become significant in retrospect) and partly because incorporating a live horse was beyond the resources of the theatre that originally staged it.
In the animated adaptation of The Chronicles of Narnia adventure The Lion, The Witch and The Wardrobe, Father Christmas does not appear. Instead Aslan gives the children their weapons.
Several characters are taken out of Disney's adaptation of The Jungle Book, perhaps most notably Tabaqui the Jackal. Most of them do not appear in the live action adaptation either (though the second more loyal sequel Mowgli's Story features Tabaqui and a few others).
The stage adaptation of Mort skips the Librarian due to the difficulty the original production had getting an orang-utan costume. It also replaces Rincewind with a wizard called Stibbons (I think before Ponder appeared in the books) so they could use a "generic" wizard costume rather than Rinso's canonical outfit.
Hyzenthlay's friend Thethuthinang and Nelthilta, the turncoat doe
Plus the mouse Hazel rescues from a hawk on Watership down, who is actually the character in the book that informs the rabbits that the Efrafans have gathered below the down and are planning to attack.
Liir from Wicked (along with most of the characters).
In the cartoon adaptation of Animal Farm, Mollie and Clover are absent. Benjamin the donkey fills in for Clover, if anything.
The original 1902 stage version of The Wizard of Oz removes the Wicked Witch and Toto (who was replaced with a cow named Muriel).
Early Thomas And Friends episodes omitted many one shot or background characters used in The Railway Series novels they were adapted from, with Thomas or some other recurring engine taking their place. Jinty and Pug are absent in episodes adapted from "The Eight Famous Engines" for example, while, due to lacking budget for a model of The Flying Scotsman, "Tender Engines" was loosely adapted from "Tenders For Henry", with only the engines' tenders being shown in a cameo.
Numerous characters from the books (including the Mountain and Small Railway Engines) will also never appear in the television series now that it has broken away from The Railway Series.
When The Relic was adapted to film, Agent Pendergast was written out and Lieutenant D'Agosta was promoted into his role. Pendergast became the Break-Out Character of the novel and is featured as the main character of all the novels that follow. The series is informally titled "The Agent Pendergast Series."
In the original BBC radio version of The Flight of the Conchords, the optimistic New Zealanders trying to make it big in Britain have an even more optimistic Cloud Cuckoo Lander manager, played by Welsh character actor Rob Brydon. Sadly, the magnificent Brydon who did so much to make the radio series work is dropped completely from the TV adaptation.
The live action film version of King of Fighters omitted the vast majority of the cast, in favor of focusing on Kyo, Iori, Mai, Terry, and Rugal.
In the anime adaption of Disgaea, Big Sis Prinny is left out, which is important as she's Laharl's mother and her death is the reason he's so bitter towards Love
A few Pokémon characters never appeared in the anime. With the Porygon episode causing a seizure incident, its evolutions will never appear in an anime episode. Quite a number of human characters do not appear as well, including Janine, Cheren, and anyone involved in Team Plasma.
In the CLANNADVisual Novel, Kappei was actually an important (if late introduced) character with his own ending and everything, but so far has not appeared in any Clannad anime adaptation ever.
The He-Man live action movie dumped Orko for a stand-in character who filled the same role.
Five hats means that five tropers think it is ready to publish.
You are saying that you think this draft is ready to be published. That means the description is not ambiguous,
it doesn't duplicate an existing trope, there are at least three examples, and the title makes sense.
Is that what you meant to do?
You are saying this draft has a ready-to-publish hat it does not deserve and you are taking it back.