What's a writer to do when a minor character that he created for a show suddenly becomes much more popular than the other members of the cast? Why, re-write him as a (if not the) main character of course!
This is that character. Usually starring in a sitcom, the Breakout Character quickly grabs hold of the audience's attention and writers take advantage of this energy. Someone who was once a one-note C-character (such as a Satellite Character or a Living Prop) becomes a central part of the regular cast. Often liable to lead to a Spin-Off, or be subject to becoming an Adaptational Badass. Sometimes a Breakout Character becomes such because he fills a niche in the cast that wasn't previously filled or acts as an impressive foil to the Hero.
When a character gets a larger- but still supporting- role because of the fanbase, that is simply an Ensemble Dark Horse (which they also are even if they don't get any increased role). Ascended Extra is when a character gains any sort of increased role regardless of the character's popularity (or lack thereof). When a character simply takes over the existing show, see Spotlight-Stealing Squad.
It isn't always good though. Sometimes if a Breakout Character character gets too much screentime they risk making the audience feel that the character is overexposed or worse, become a Scrappy. Always remember that you still have other characters in the cast who need screen time too and just because one character is extremely popular doesn't mean that the others should always be Demoted to Extra. This pitfall can be avoided by occasionally giving breaks to the Breakout, other characters can get their stories told and his fans will patiently wait for him to reappear in the story and be all the more excited when he does reappear.
Trying to intentionally make breakout character before they're even introduced to audiences can also lead to some unfortunate results.
Also see Breakout Villain, a Sub-Trope for villain character, and Iconic Sequel Character, a Sub-Trope for when the Breakout Character in question doesn't appear until a sequel. Compare to Breakup Breakout. Contrast The Artifact.
Although the Geico Gecko was always the main character of his own commercials, he started out as a complainer, annoyed that the company's name was similar to his own, causing him to get calls from prospective customers. When he proved sufficiently popular, he became the company's mascot (justified by a commercial that actually depicts him getting hired as the company spokesman...spokesreptile?), the focus of most commercials, and, inexplicably, changed accents. The Geico Cavemen were so popular they got their own show. Of course, that didn't last very long.
In one campaign, commercials for Capital One credit cards featured rampaging Barbarian hordes, who would mercilessly attack anyone not bearing the correct card. Because Barbarians are more interesting than shoppers, they quickly became the main characters of these commercials, using the cards themselves to stock up for their various acts of mayhem.
Sugar Bear, the mascot for Super Sugar Crisp (now Super Golden Crisp) cereal, started as the least-of-the-least on a cartoon show sponsored by Post. Of the characters in that show, he's the only one still in use.
In the UK, the character Aleksandr Orlov, a meerkat, was created to advertise an insurance comparison site called "compare the market.com", presumably based on the idea that "compare the market" and "Compare the Meerkat" sound similar if you say them in a silly accent. The character has become a huge success, spawning his own franchise (books, toys, general merch etc...). He's even been interviewed on a talkshow, despite being a CGI character. His wikipedia page is actually longer and more detailed than that of the company he was created to promote.
Fate Testarossa. Originally The Dragon of the first series, her interplay with Nanoha after they joined forces proved so popular, the two of them were made equal partners starting from season two, and she is essentially a co-protagonist from then on.
Nanoha herself was originally a very minor character from Triangle Heart 3: Sweet Songs Forever. She proved popular enough to get her own game, and soon afterwards - a Spin-Off show. The original concept of the show was a straight up Magical Girl series until somebody in the staff commented about her design resemblance to a Gundam. The creators took the idea and ran with it, packing the show to the brim with Magitek, tense battles that wouldn't look out of place if mages were substituted with Humongous Mecha, and, as the seasons progressed, an increasing number of Military Science-Fiction and Space Opera elements. As of Nanoha herself, she is now one of the most iconic and widely recognizable Magical Girls, and by a large margin the most Bad Ass. Very few people realise that she was originally a supporting character in another series that they most likely never even heard about.
Hiei from YuYu Hakusho was originally meant to be a one-shot character (this is clear in his first appearance), but he proved so popular with fans that he was given another appearance - and continued to prove popular enough with fans to make him a main character, complete with his own plotlines and backstory.
Code Geass: Jeremiah Gottwald was supposed to die early in the series' run, but proved to be so popular that he was allowed to survive and become a more important character than originally planned.
Zelgadis the chimera and Amelia the princess were protagonist duo Gourry and Lina's allies for a couple of novels and were eventually replaced. When the anime began branching off from the novels, chimera and princess had proven popular enough to become as major characters and as integral to the story as Lina and Gourry. All adaptations of manga and games have followed suit with this. The replacements, on the other hand, are virtually unknown.
Xellos the demonic priest is also this combined with Ensemble Dark Horse; he only appears in five books (cameoing in the last one); like Zelgadis and Amelia above, he became more integral as the franchise evolved.
Vegeta from Dragon Ball Z was originally supposed to be just the Big Bad for the Saiyan saga, but proved to be so popular among the fans that Akira Toriyama continued using him and turned him into the Anti-Hero as a result.
Frieza. He is often cited as one of the best and most important villains in the franchise. His popularity has reached such a point that is remembered on several occasions, including in the latest film "The Battle of the Gods".
Broly. The non-canon (read: not part of the original manga) Monster of the Week in one of the movies proved so popular that not only did he get two more movies as the antagonist, but is now practically guaranteed to show up in every tie-in video game, regardless of whether or not he fits into the story. His English voice actor, Vic Mignogna, has a love-hate relationship with this. He likes Broly as a character, but doing the voice is hell on his vocal chords, so he was understandably dismayed when he and the others at Funimation found out that Broly was going to be more than a one-time gig.
Bardock, father of Goku, was an anime creation for a special going into detail the events that led up to the destruction of Planet Vegeta. The special was well received, and Bardock was actually so well liked by Akira Toriyama that he actually included him in the manga. Years down the line, Bardock became more heavily featured in the video games and eventually got a spinoff manga and OVA where he got to turn Super Saiyan too.
Osu! Karate Bu: Anti-Hero Yoshiyuki Takagi from the manga was originally the mentor of the original main character, Tadashi Matsushita. Takagi became so popular with readers, that the author decided to make him the main character, reducing Matsushita to a supporting role.
Shikamaru Nara started off the series as being one of the definitive darkhorses. Following the surge of popularity, Shikamaru was given more prominence and Character Development in the series. Come Shippuden, he finally was upgraded to being a Main Character, even given an entire arc dedicated to him.
To Love-Ru - The sequel series took fan favorite Golden Darkness and promoted her to the co-protagonist position, alongside Momo.
Syaoran Li of Cardcaptor Sakura. Originally a secondary character, Syaoran became a more prominant friend (and later love interest) for Sakura, with some later episodes revolving more around his perspective than the title character. Like Sakura, Syaoran also provided the basis for several other CLAMP characters, many of them just as (or more) prominant than the former. Somewhat ironically Nelvana and WB attempted to endorse Syaoran as co lead for the ''Cardcaptors' dub to appeal to male audiences early on in its run.
In One Piece, Chopper. Most likely due to him being the most marketable character. (So much that some believe 4kids skipped arcs just to get to Chopper so they could rake in the cash.) What really brought him out was the Chopperman bits. So much so that he now has his own spinoff manga series! He's a relatively mild example, as he was intended to be one of the (currently) 9 main characters from the start. But the author probably didn't expect him to become that iconic.
And the irony is that in-universe, he is merely thought of as the Straw Hat Crew's pet, only getting a bounty after Enies Lobby of 50 berries, highlighting how unimportant the Marines consider him. If only they knew...
A non-character example: the Duel Monsters card game, which was originally meant as just one of many games played throughout the series, but eventually became so popular that the series was given a Re Tool to make it the only game that mattered- even the few games played that weren't Duel Monsters were still about battling monsters. This carried over to the sequelseries, where there's not even a hint of any other games.
For a character example, Kaiba, who was made to be a one use enemy for the Duel Monsters chapter and got to come back as a larger villain due to popularity, then as one of the most important characters after that, tied to the Pharaoh's backstory itself.
Accelerator was a villain who slaughtered 10,031 clones and was eventually stopped by the protagonist, but he was so popular with the fanbase that he was given a chance to atone for it. Ever since then, he's become the Deuteragonist of the series. He later got his own spin-off series, A Certain Scientific Accelerator.
Kumagawa Misogi is a truly outstanding example of this. Introduced as The Dreaded several chapters before his appearance as the second big bad, he then proceeds to be essentially the biggest, most destructively psychopathic troll the series had seen up to that point. However, through a combination of interesting character traits and fourth wall breaking humor he rocketed to the top of the second character poll, beating out the second place character (Kurokami Medaka, the main character) by several times the amount votes. His pinup in the poll results has him crying tears of joy at finally winning (and, probably, achieving his wish to see all the female characters in naked aprons). He's even getting his own spin-off!
Naze Youka also qualifies to a lesser extent. Originally just a member of the Class 13, once it was revealed she was the older sister to the titular character, her significance continued to increase, as well as her popularity. She's now Vice-President of the Student Council.
In Gunslinger Girl, Triela. Originally a secondary character, she replaces Henrietta as the central character in season 2 of the anime.
For Hayate the Combat Butler, in the Popularity Polls for the manga, Hinagiku Katsura came in the first place by a landslide in every single contest. She's also the most marketed character by a huge margin with figurines of her coming out before anyone else's, two special character albums, and having the greatest volume of stuff put out.
Osaka from Azumanga Daioh got considerably less focus than the other main characters in the first volume of the manga, mostly due to being introduced towards the tail end of the book. Compare now where she's pretty much the face of the series.
Yun of Simoun. Originally tripping all of the Sacrificial Lamb flags (not in the OP when the character that's introduced alongside her is, portrayed as a prideful, somewhat antisocial fool who refuses to listen to the wisdom of others, etc.), creators reacted to her unexpected popularity by giving her one of the most important roles in the story.
Most people equate JoJo's Bizarre Adventure with Jotaro Kujo, Dio Brando, and the psychic powers known as Stands (most importantly THE WORLD), without realizing that Jotaro is only the protagonist of Part 3. Of 8. And that the parts that preceded Part 3 featured no Stands at all, and instead a martial art that emulates sunlight so you can fight immortal vampires.
Admiral Gar Stazi of Star Wars: Legacy. Introduced basically to explain what happened to a pre-existing galactic faction, his appearance featured some memorable examples of badassery, prompting the author to write more and then some more stories about him. By the end of the series, he basically has his own secondary plotline, spanning one third of the issues.
Occurred on a meta-level with the official "Tintin font◊" that is used for the album titles. It looks vaguely "far east" because it was originally used for The Blue Lotus, which takes place in China. However it stuck around and became the font for all subsequent titles.
Back in the early to mid 1980s, The X-Men comics were known for their ensemble cast. Everyone was allowed their moments to shine. However, Wolverine eventually became popular, and over the next decade or so, he not only had his own solo comic, but also seemed required to be in every X-Men comic (and plenty of other ones) as well. It got to the point where one writer even lampshaded this by including one scene where Wolverine complained to his leader that he couldn't be assigned to every X-Men subgroup. In adaptations, the franchise has made a complete shift from "X-Men" to "Wolverine and some other guys in the background." Can you say Wolverine Publicity? Wolverine wasn't even an X-Men character originally to begin with. He was originally meant to be a one-shot nemesis for the Incredible Hulk.
The Avengers has Hawkeye. Originally a villain and one of then-villain Black Widow's many short lived boyfriends that she manipulates into fighting Iron Man. Then, Hawkeye joined the Avengers, where he became The Lancer to Captain America. He would then go on to get several largely successful miniseries until finally becoming the leader of his own Avengers team in the form of the West Coast Avengers, which lasted quite a while. Then he fell back into the C-list, but in recent times has returned as one of the core Avengers, being a member or supporting member of most Avengers team, and to tie in with the 2012 film even got his own ongoing that, currently, is the most critically acclaimed book (or tying for it) Marvel is publishing, while also being a core cast member of the Avengers Marvel Now! book, the Avengers Assemble comic book, and the Secret Avengers.
Amazing Spider-Man #42: Peter Parker has a blind date with the neighbor's niece, Mary Jane Watson, whom the writer and artist intend as a minor character to play second banana to the real love interest, Gwen Stacy. But when in the final panel Mary Jane's face is finally seen and she says the much-quoted words "Face it, tiger, you just hit the jackpot!", the letters calling for her to become Peter's girlfriend start coming. Stan Lee and John Romita eventually discover that no matter what they do, MJ is more popular with the readers than designated love interest Gwen. To cut a long and complex story short, 250 issues later Mary Jane finally consents to become Spider-Man's wife.
Two alternate universe characters, Spider-Girl and Ultimate Spider-Man, were suppose to be a one-shot and a mini series respectively. Sales and fan response were so positive that Marvel decided to create an entire alternate universe and a line of comics for both characters, The Marvel Comics 2 and Ultimate Marvel.
Heck, Spidey's one himself. He was originally intended to be a one-shot character in the final issue of anthology series Amazing Fantasy. Stan Lee's editor was against a spider-based superhero appearing in comics since it was generally common that people hated spiders. After his appearance in the comic he wasn't intended to appear again but the readers liked him so much from this little 11-page story he got his own series less than a year later, and nowadays he's easily one of the most popular and recognizable comic book characters in history.
Static of the Milestone Comics line. Originally created as one series among many during the companies run in the 90's, Static started off as a fan favorite. Later on, he was even star of the, at the time, company's swan song; Static Shock: Rebirth of the Cool. Due in part to his cartoon series, Static has gone on to become the most well known and famous of the Milestone characters, and has since become the poster child of the line.
Vincent Van Goat from Quantum and Woody. Originally intended as a one-issue gag, he became so popular that fans brought goat-themed toys, drawings, and memorabilia during promotional tours.
Marv from Sin City proved popular enough in the very first story that the series switched to being told in Anachronic Order so that he could reappear after getting killed off.
Nightwing (Dick Grayson), the first Robin, and formerly Batman. He started off as a kid sidekick in the 1940's, finally officially becoming his own hero in the 1980's in the Teen Titans comics. From there, he got his own series which ran for over one hundred issues, but it was cancelled... because he was getting multiple ongoings once he became Batman. Geoff Johns and Dan DiDio went on to later describe him as "The Heart and Soul" of the entire DC Universe. There were plans to kill him off (permanently), but the idea was scrapped because of the above reason and because he was just too popular. Most fans don't consider Azrael to be a true successor to Batman, and in fact, hated the very idea of him being Batman. The same fans didn't complain when Dick became Batman, and plenty of fans were disappointed when it was announced that he would return to his Nightwing persona in the New 52.
Batman himself. Originally he was just one of many characters being published in the anthology series Detective Comics. He then became the most prominent character in the book as well as the most popular, and now, he's probably the second most well known superhero, right after Superman.
Likewise, Doom Patrol is relatively obscure, but Garfield Logan (Beast Boy, Changeling, or Menagerie depending on the era) certainly got a boost in prominance after the first Patrol was destroyed.
The Smurfs made their debut as one-shot supporting characters in Johann and Peewit, a Belgian comic book about a heroic king's page and his jester sidekick. The pair went on adventures that often featured magical creatures of the author's invention. The Smurfs were one such group of creatures, and were only intended to appear in one story. They became so popular, however, that the author kept bringing them back, and within a year they had received their own spin-off series, which completely eclipsed Johann and Peewit in popularity. What goes around comes around: Johan and Peewit (now named "Peewee") became minor characters in the Smurfs cartoon, eventually getting entire episodes to themselves (with the Smurfs showing up as cameos at the most).
Princess Sally Acorn, from "Archie Comics' Sonic the Hedgehog" and "Sonic Sat AM". Had more of a supporting role in early Archie. Arguably as prominent a character as Sonic himself later on. This is even more evident counting her earlier background as a minor captive in the games.
Mina the Mongoose, first appear in the issue #76 of "Archie Comics' Sonic the Hedgehog" Although, She was originally as a background character in the comic issue of #52, then her appearances shows up in the later issues, starting with her super speed before meeting the Freedom Fighters. She was first discovered by Sonic the Hedgehog after Dr. Eggman captured her mother and roboticized her, leaving Mina mourning and vulnerable to capture by Shadowbots. She fell in love with Sonic after spending more time with him, and tried to win over his heart. When she realized that Sonic loved Sally Acorn, she gave up on pursuing him, and she instead began a singing career, eventually becoming the lead singer for Knothole Knuts and later the Forget Me Knots. Though she left the Knothole Freedom Fighters, she remains an ally and friend to them, as well as an active-if somewhat misdirected at times-citizen of New Mobotropolis. Mina, her character design has become very popular among Sonic fans, that some of her supporters wish for her to appear in the next future Sonic the Hedgehog video games. But, still no word from the Sega Corporation.
Dr. Robotnik became this in Archie's Sonic X comic. It got to the point where Robotnik was practically the main character and the series was more about the many misadventures he and his robot mooks get into than about Sonic himself. Quite impressive considering that he was a side character at best when the series started.
Swerve, a formerly minor background character, has become this in IDW's recent Transformers comic largely because he's totally hilarious, spending all of his time making snarky comments and lampshading the many tropes and cliches that everyone else stubbles into. He also gives the greatest idea for a prank ever, moving around the furniture in someone's room while they're sleeping then pretending that nothing changed the next day (he also says that he's planning on taking it up a level by wheeling the victim into another room while they're sleeping]]).
Bucky Barnes from Captain America. He was just another teen sidekick when introduced, and then killed off in flashback by Stan Lee when he reintroduced Cap into the Silver Age. For decades Bucky became a running joke as "the only character to stay dead" in comics. Fast forward to 2005 and at the very beginning of his run Ed Brubaker proceeds to bring Bucky back as the Winter Soldier, a brainwashed assassin used by the Russians during the Cold War who is eventually freed from control and goes on to become a well-characterized anti-hero. And then when original Captain America Steve Rogers was killed, Bucky wound up taking over the mantle to honor his partner. And he wound up becoming such a hit that when Steve was inevitably brought back to life, the fans actually didn't want him resuming his old identity and replacing Bucky.
Blade from Marvel's Tomb Of Dracula. He debuted in issue #10 as a recurring ally to Quincy Harker's vampire hunting team. Harker's team who included regulars Frank Drake and Rachel Van Helsing were the constants of Tomb and can be considered the actal protagonists of the series. Blade did have at least one short story arc dedicated to his hunt for Deacon Frost. But he dissapeared after his mission was completed and the focus turned back to Harker's team. Today, Blade is (other than Dracula himself), considered the most longeval character from that comic. He would go on to appear in numerous 90's comic such as Nightstalkers and his own title before actually becoming the star of a series of movies and a TV series starting in 1998.
Deadpool was originally designed to be a one-shot villain of the New Mutants and a parody of DC Comics' Deathstroke. He was later teamed up with Cable and briefly joined the X-Men and X-Force. His sociopathic comedy and constant fourth wall breaking have pushed him to the elite of Marvel Characters with his popularity rivaling that of Wolverine and Spider-Man.
Ironically Deathstroke also fits this trope. Another one-shot villain that went over big with fans.
The Dutch character Douwe Dabbert was never planned to have his own series: he was originally a supporting character in the one-shot comic The Spoiled Princess. However, he became so popular that he quickly got his own series that ran for 26 years, while the eponymous princess Pauline vanished from view and only returned for a single story years later.
PJ Fan Fiction/The Perseus Attraction: Luke Castellan. Luke was originally intended to become the main antagonist, and Percy's rival for Annabeth. However, the breakout of his first real appearance (doing squats in a sword class listening to Noah and the Whale and Katy Perry) quickly gained him recognition among the reviewers. He further solidified his position by making stupid dream appearances with Kronsis throughout the first season, and then when he saved the entire Perseus Attraction main cast by recreating The Princess Bride (as the 'Man in Pink.) By season 3, which covers The Titan's Curse, Luke appears tag teaming the sky with Annabeth, even though he should have no part in the story at all at all, in a typically 'Luke' fashion, making him all but untouchable as the Breakout.
TD from The Non-Bronyverse was originally conceived as the protagonist for a silly one-shot story, but whose popularity (no doubt helped by his Deadpan Snarker tendencies) ended up spawning a full-fledged story, and later an entire series of works.
In canon, Lightning Dust is a one episode foil that serves to show why teamwork trumps solo flying. In the Reading Rainbowverse, she becomes the center of an ever-increasingly dysfunctional family and the personal target of an Eldritch Abomination who dates a changeling.
Anything Her Heart Desires: Ingrid Hanna Andersen. Word of God is that she was not only intended to be a very minor character, but was written to be as unimpressive as possible. But if you're writing a "problematic Elsanna" F Rozen fic, and Elsa & Anna aren't speaking, someone's going to fill the void. By the end of the story, Elsingrid.
Film - Animated
101 Dalmatians: Cruella de Vil, Cruella de Vil... What does it say that the 1961 animated version treated her simply as the villain, but the '90s live-action films were essentially a Villain-Based Franchise focused on Cruella? In fact, Cruella was the only human character to return in the live-action sequel. Of course, this was compounded by the dogs not talking in the live-action versions, although they still had Amplified Animal Aptitude. Ironically, the original book had a sequel in which Cruella only had a small role.
Iago from Aladdin. His popularity has grown to the point that he's arguably more iconic than Aladdin himself, and he even has a Heel-Face Turn. Only the Genie rivals him in popularity.
Tinker Bell and, to an extent, Tick-Tock the Crocodile from Peter Pan
In the animated movie The Emperor's New Groove, Yzma's servant Kronk delivers many of the film's funnier moments. Because of this, and partly because he was voiced by the deep-voiced Patrick Warburton, Kronk was popular enough among the fanbase to be the main character in the sequel, Kronk's New Groove.
Timon and Pumbaa from The Lion King. They got their own TV show, a P.O.V. Sequel, and have tons of fanart dedicated to them, far more than Simba, Nala or Mufasa get.
The three hyenas, Shenzi, Banzai, and Ed. They have a cult following and are immensely popular in fanart, particularly Shenzi
Chomper from The Land Before Time film series. He was originally just a guest character brought in for the second film. But he proved to be so popular with fans and critics that he was brought back as a supporting character in the fifth film. Eventually, he became a main character in the TV series as well.
Despite being almost pure comedy relief, the Penguins and King Julien from Madagascar and its sequel were so obscenely popular that they got their own Spin-Off, The Penguins of Madagascar. Nobody really cared that it seemed to take place in a completely Alternate Universe (there's no feasible way the two series can co-exist) - the characters are just that awesome.
Puss in Boots, the swashbuckling feline who became the primary protagonist of the 2011 spin-off prequel Puss in Boots, was a supporting character who first appeared in Shrek 2 as an assassin on Shrek and Donkey's life before making amends and joining them as a Power Trio in all the other sequels. Audience and critics alike gave him credit for stealing the show. Even after the Shrek franchise ended, his own popular spinoff has left room for an entirely new franchise focused on him.
The Incredibles, if script revisions count for this trope. In Brad Bird's first draft, the main antagonist was a James Bond-style Diabolical Mastermind named Xerek. There was also a minor villain, an old enemy of Bob and Helen's, named Syndrome, who attacks their home early in the first act and dies shortly afterward when the house blows up. With his one scene, Syndrome made a bigger impression on the initial readers than Xerek did, so Brad Bird made Syndrome the Big Bad and relegated Xerek to a role in the spinoff comicbook series.
Violet Parr became one of Pixar's most popular female characters and fans have stated they would like her as the protagonist in the upcoming sequel.
A Goofy Movie introduced Bobby, who became insanely popular for a brand new Plucky Comic Relief character who only appeared in about 20% of the movie and had no familial relationships with other characters, as well as an "exception" for many Pauly Shore haters but not at all for his fans. The sequel makes him a main character and gives him a closer relationship to Max and PJ while the other new characters from the movie disappear without explanation.
Scrat from the Ice Age franchise, quickly rose to the most popular character in the film, he even has a special segment of his own in the first film.
Finding Nemo has Dory. She's so popular, the upcoming sequel Finding Dory will give her a larger role.
Tai Lung and Lord Shen, the villains of the Kung Fu Panda movies, are some of the most popular characters, often overshadowing the titular panda in fanwork.
The scene-stealing Minions from Despicable Me definitely qualify. They're little, cute, hilarious, and practically the only reason why anyone watches the films. They have starred in countless mini-films, dominate the soundtrack, have earned the position of official Mascot of Universal Pictures, and are getting a feature film of their own in 2014 Minions.
The Triplets from Brave; Hamish, Harris and Hubert stole the show and the viewers' hearts. If ever Brave gets a sequel or a spinoff, there will very likely be more focus on them.
Vanellope von Schweetz, the adorable, sharp tongued sidekick of Wreck-It Ralph; only thing is there was so much focus on her, and her development of character, the movie should have been named after her (And in Japan, it basically was - there the movie is calledSugar Rush after her game instead of anything having to do with Ralph).
Elsa the Snow Queen from Frozen. Even before the movie's release, fans stated their love for Elsa because of her powers, complicated emotions, and beauty. The love for her only grew after the release: Many even wanted Elsa to be the actual protagonist instead of Anna.
Film - Live-Action
Dazed and Confused's David Wooderson. Originally a more minor character, Richard Linklater was so impressed with Matthew McConaughey's performance, he ended up writing much more dialogue for him.
In the first Friday the 13th (1980) Jason was supposed to have drowned before the events of the film. His mother is actually the killer in this film. However, the writer saw the movie Carrie (1976) and wanted a shocker ending, so Jason crawls out of the lake at the end of the movie. Sequels would have Jason as the main character, though he did not get his iconic hockey mask until the third movie.
The Pink Panther was originally meant to be about David Niven's jewel thief character, with Inspector Clouseau bumbling antagonist. Then a last-minute casting change put Peter Sellers in the Clouseau role, and the rest is history. Let's face it, the whole thing ended up turned around. The thief, the antihero, the glamour romance interest and the plot all end up being forgotten in favour of Clouseau. The animated Pink Panther that appeared in the opening credits to the movies ended up as an independent character.
Agent Phil Coulson is the very definition of this. In the first Iron Man, he had a minor role as a S.H.I.E.L.D. agent. Insanely positive fan reaction to his character got his role somewhat expanded in Iron Man 2, and in Thor and The Avengers he's one of the central characters. Even his own death couldn't stop him, as he just was resurrected to lead the TV series Agents of S.H.I.E.L.D.. The guy headlines his own short films, has his own comic book series, and from the looks of it, is getting bigger and bigger.
It's worth noting that he's such a fan favorite that he's crossed universes. His actor had a few minor spots as an FBI agent on The West Wing and some fan fiction has run with the idea that the characters are actually the same person, and that Phil Coulson was merely undercover in the FBI.
Iron Man fits this because before the movies came out, he was being shifted into the background. He was still a mainline superhero in the Marvel Universe, but people wanted to see everyone else more. Then the movies came out, and suddenly Iron Man is one of the biggest things ever — to the point that he's overshadowed Spider-Man in popularity these days.
Loki. Despite having previously appeared in Thor, it wasn't until his depiction in The Avengers that Loki became almost as merchandise-able as the heroes themselves. Suddenly people wanted more of Loki and actor Tom Hiddleston to the point that Target even released their own Thor: Dark World Blu-ray packaging that features only Loki on the cover.
Even Darth Vader is one of these. In the first movie, he barely even appears, and when he does, he's usually being subordinate to Grand Moff Tarkin. In early drafts of the script, he was even killed in the Death Star trench run, and was never intended to be Luke's father. Fortunately, however, Lucas decided to insert a shot of him escaping as a Sequel Hook, and he ended up becoming the big villain of the series, enough to warrant a three-movie-long Start of Darkness arc.
Admiral Piett is a more minor example. Viewers found him so sympathetic in Episode V that he was written in to Episode VI to reprise his own role as Admiral of Vader's fleet... and then he dies. (At least he goes down fighting.)
Boba Fett became so popular that a decent chunk of the prequel trilogy's second film was dedicated to his origin story. His father became the sole genetic basis for the Grand Army of the Republic, one of the single most influential factions in the entire saga. He was even digitally added into a restored scene of A New Hope when Lucas released the Special Editions of the original trilogy. This in addition to his role as a supporting character and protagonist in the Expanded Universe stories. All of this is pretty crazy when you realize he has just two lines in Episode V and none in Episode VI.
Slimer from Ghostbusters didn't even have a name in the original film, yet he wound up the mascot of the cartoon series and franchise. The 3rd season of the cartoon series was even titled Slimer! and the Real Ghostbusters. His semi-official name during production of the first film was Onionhead, but the fans nicknamed him Slimer and it stuck.
Captain Jack Sparrow. The original intention was for the series to focus on the adventures of up-and-coming pirate Will Turner. Jack was meant to be a freewheeling, accidental mentor, with a large role only in the first film. But Johnny Depp ended up re-imagining Jack in such a hilarious, fascinating way that he dominates the first movie. His increased role continues into the sequels until the fourth film, where he's the only star and the previous main characters are not present.
Barbossa was originally only meant to be a Foil and nemesis for Jack in the first film, but proved to be so memorable (due to Geoffrey Rush's incredible performance) that the writers decided to resurrect him at the end of the second film, leading him to become one of the main characters in the third and fourth.
Clerks - Jay and Silent Bob are originally bit characters. Smith put them again in Mallrats only because he wanted to see Jason Mewes play Jay one more time. According to his blog, he had no idea they were so popular at all until the screening of Mallrats at 1995 San Diego Comic Con. After that, he felt confident enough to put them as bit characters again in Chasing Amy, to give them a more prominent part in Dogma, and finally to make a whole movie about them: Jay and Silent Bob Strike Back. And, of course, they made their return in Clerks II.
Burt Gummer, a supporting character in the original Tremors, wound up stealing the franchise so completely that the TV series never bothered to give leads Kevin Bacon or Fred Ward so much as a Continuity Nod.
American Pie - Stifler starts out as a supporting character, establishing himself as a jerkass who is only interested in sex. In the sequel, he actually gets involved in the main plot, getting much more screen time even though he continues to be the same selfish jerk throughout the entire film. The third movie goes much further, with Stifler as the central character, making the ultimate transition into Jerk with a Heart of Gold, which took up most of the film's plot.
Punic Wars-era strong man Maciste (played by Bartolomeo Pagano) was the breakout character of the Italian epic Cabiria (1914). Pagano reprised his role as the star of 25 Maciste films in the following twelve years, and a further slew of Sword And Sandal films during the 1960s and 1970s starred various other actors in the same role.
The Lost Boys - Edgar Frog was merely a supporting character in the first film while Michael was the protagonist. But in the sequels, Edgar becomes the primary focus of the series, predominantly in the third film.
The Ponson Du Terrial 19th Century saga that came to be known as Rocambole was originally called The Dramas of Paris the first Book of which was sub titled The Mysterious Inheritance. The Hero was Armand de Kurgas and the Big Bad was his half brother and Evil Counterpart Adrea Feliponi aka Sir Williams. Baccarat was a supporting character, not even the most prominent female, and Rocmabole was a Minor character who only show sup near the end. But those latter 2 character were the most popular.
So in the second Novel Rocambole becomes The Dragon and Baccaret the main Hero of the story, and given her own Evil Counterpart in Femme Fatale Torquise. Andrea is still the Big Bad but Armand is absent much of the story and seems useless when he is there.
3rd book Baccarat is still the lead protagonist, now dealing with her Evil Doppleganger half sister. Armand's role is even smaller, Rocambole is Dragon In Cheif to a mute Andrea serving more[[Spoiler: and becomes Dragon Ascendent]]
Then he get a Heel-Face Turn and becomes The Hero of the saga with the other main character phased out all together.
Slappy, the Demonic Dummy of Goosebumps fame was a minor character in the first Night of the Living Dummy book, but in the sequels was brought back as the primary villain.
Samuel Vimes was originally intended to be a minor character in City Watch sub-series, with Carrot being the major character. Suffice it to say, Samuel Vimes is likely only beaten by Death and the Librarian for the number of books he's in.
Death. He started out as a joke in The Colour of Magic. He appears in nearly all of the books, sometimes as a main character.
The Lumatere Chronicles: Froi. He begins as an immoral thief and supreme Butt Monkey who just cannot catch a break, and deserves it to a degree as well, but he grows on the group of Exiles when Finnikin and Evanjalin save him from slave traders. He begins to speak the language of Lumatere, albeit poorly. Later on, he helps gather the Lumateren exiles from around the continent in order to regain the kingdom and helps to rebuild Lumatere as well. In book two, Froi of the Exiles, he takes center stage and the readers are shown just how much Character Development he's gone through.
Rupert Psmith was a supporting character in P. G. Wodehouse's school-story Mike, but quickly eclipsed the stolid protagonist to become the star of the novel. In later books he is the central character. As Evelyn Waugh wrote: "One can date exactly the first moment when Wodehouse was touched by the sacred flame. It occurs halfway through Mike ... Psmith appears and the light is kindled which has burned with growing brilliancy for half a century."
The novels ''Relic'' and ''Reliquary'' have Batman-like, super-competent FBI Agent Pendergast as the tertiary main character (who didn't even manage to appear in the film of the book). The authors subsequently made him the main character of their next several books. Note that this wiki's own page for the series even bears his name.
Reginald "Turnip" Fitzhugh from the Pink Carnation series by Lauren Willig. In the first few books, he's a very minor character — young and handsome, but so daft and foppish that no one takes him seriously. He appears in a few society scenes, but has nothing to do with the plot. Turnip was so popular with fans, however, that Willig gave him his own book, The Mischief of the Mistletoe.
The Icewind Dale Trilogy was originally supposed to be about Wulfgar and his friends, one of whom was a dark elf named Drizzt Do'Urden. The first book is pretty much like this, the second book has everybody pretty much share the spotlight, and by the third book Drizzt has clearly become the star. Salvatore followed up with The Dark Elf Trilogy, a prequel series which told Drizzt's life story before he met the others, cementing Drizzt's status as The Hero. The greater series as a whole became known as The Legend of Drizzt.
Albert Campion in the series of novels by Margery Allingham. He was originally just a minor character in The Crime at Black Dudley, but Margery Allingham found him so fascinating that he became the lead character in a series of novels.
Interview with the Vampire is Louis's story, with Lestat as a villain and supporting character (he's actually absent for a good chunk of the novel midway). But thanks to all the positive feedback he got in Interview, Rice saw fit to not only make the sequel from Lestat's POV, but to pretty much make him the protagonist of the whole damn The Vampire Chronicles series.
Ramona Quimby, star of Beverly Cleary's beloved book series started off as a minor character in the Henry Huggins series.
Edward D. Hoch originally wrote Captain Leopold as a supporting character in a story about private investigator Al Darlan; he went on to be Hoch's main detective.
Evvy of the Circle of Magic universe by Tamora Pierce. She was one of the students that the first four protagonists found in their travels, but thanks to her terrible living situation Briar decided to take her with him, whereas the other students were okay where they were and haven't appeared since. Evvy was the protagonist of Melting Stones in the next series and tritagonist in Battle Magic with Briar and Rosethorn after that.
Arthur 'The Fonz' Fonzarelli from Happy Days is such a good example, few people know it is an example at all. Happy Days originally was written around Ron Howard's Richie Cunningham character with Anson William's Potsie as his co-lead. The Fonz character was only supposed to be an incidental character, but his popularity grew so dramatically that the network even tried to change the title to Fonzie's Happy Days until Henry Winkler himself (along with the rest of the cast and the director) protested it. Most of the plots did begin to revolve around The Fonz character and the Animated Adaptation did end up being called the The Fonz and the Happy Days Gang.
Believe it not, The Doctor himself qualifies. True, he's the title character and his actor got top billing, but the producers had always intended for the show's protagonist to be Ian Chesterton, the dashing science teacher and man of action who served as one of the Doctor's first companions. The Doctor was envisioned as more of a mentor figure and guide. Thanks to William Hartnell's authoritative performance, however, the Doctor quickly took over the show, and stories began to revolve around him starting with the second season.
It helped of course that all of the original cast members except for the Doctor left in the second season, leaving the Doctor as more of a familiar audience identification figure compared to all of the newer cast that came in.
Jago and Litefoot from "The Talons of Weng-Chiang" were so popular a spin-off was considered. This didn't happen but they got their own series with Big Finish.
Jack Harkness was so popular that a spinoff series followed not too long after.
Rory Williams is so popular, many viewers believed (with very good reason) that he would be the title character in "A Good Man Goes to War". And with the Doctor telling Kovarian that good men don't need rules and it's not a good idea to find out why he has so many, it basically was.
Sarah Jane Smith, who also later gained a spinoff.
Jamie McCrimmon was only supposed to be a one-off character in "The Highlanders", but ended up traveling with the Second Doctor for all but his first serial, making him the longest serving companion in terms of consecutive episodes.
The Daleks were only intended to appear in the second story and nearly didn't appear at all, but changed the direction of the show from educational to Aliens and Monsters and became the most popular characters. There were even plans for them to have a spin-off.
The Weeping Angels dethroned the Daleks as the fan voted most scariest monster, and became one the most popular of the Doctor's rogue gallery in the revived series, and thus were brought back again and again (despite never having any direct linkage to the particular story arc, with the exception of the Cracks in Time).
Bernice Summerfield was the Seventh Doctor's companion for much of the Virgin New Adventures. She ended up getting a popular Big Finish spin-off, the first Doctor Who companion to do so.
"Reverend" Jim Ignatowsky on Taxi, played by Christopher Lloyd. The character first appeared in a one-shot role in the first season, being hired to officiate Latka's green card "wedding," but he was so well-received that the producers brought him back early in Season Two and made him a regular just a few weeks in.
Exidor on Mork and Mindy was meant to be a one-shot character, but proved so popular that he was made into a recurring character.
Barnabas Collins from Dark Shadows, who was originally slated to be staked within a few weeks of his first appearance.
Benson from Soap the resident sarcastic character, who (when he left) received his own series, Benson.
Avon from Blake's 7. He was just initially supposed to be The Lancer to the titular Blake but Terry Nation (not to mention the audience) loved the spins Paul Darrow would put on his lines so much that by the second season Avon was a full-fledged Deuteragonist and when Gareth Thomas (Blake) left the series, it continued on for two more seasons with Avon as the protagonist.
Kramer from Seinfeld: Seinfeld was originally supposed to have two main characters, Jerry and George. Kramer was going to be the wacky next door neighbor that pops in every now and then. After the first episode, the network wanted a main female character, and Elaine was brought in. So the show had three main characters, and was like that for the earlier episodes. As time went on, Kramer became more and more popular, and as a result appeared in the show more often as it went on. Eventually he became one of the main four, due entirely to fans wanting to see him.
J.J. Evans from Good Times. This was made even worse when two of the main characters were either killed off or temporarily gone, making J.J. even more of the focus of the show. The original star, Esther Rolle, actually left the show over it and only came back on the condition that they clean up the J.J. character.
Many of the character of The Muppets are this. Some examples include Kermit, who started off as a supporting character on the show Sam and Friends before eventually becoming The Muppet's unofficial leader and Gonzo, whose role has expanded over time, especially in the movies, where he is one of Those Two Guys or the Lemony Narrator, but later had an imaginary film regarding his origins/species, in which he was the protagonist. He also had an expanded role in Muppet Babies as a Dogged Nice Guy toward Miss Piggy.
Miss Piggy herself started out as a bit player in a Herb Alpert and the Tijuana Brass TV Special, before getting larger and larger roles on The Muppet Show and being just behind Kermit.
Elmo from Sesame Street was a minor (originally unnamed) background Muppet in the show's early years before becoming one of the main focuses of the show and the Creator's Pet. Cookie Monster was originally a mascot for a defunct snack brand, and Grover was a minor villain in an Ed Sullivan Christmas sketch.
Star Trek: The Next Generation had Worf. Watching the first season it's clear he doesn't really have a whole lot to do other than being a Klingon hanging around the bridge and glowering at people to indicate the series was in The Future! compared to The Original Series. By later in the run entire main story arcs were devoted to the character, changes in the setting of the Star Trek universe (such as the Klingon Civil War) revolved around him, and that carried over to Deep Space Nine, which made him one of only two characters to be a regular in more than one Star Trek series.
John de Lancie's Q was the other one: the character is the only one to have appeared in all three of the contemporaneous Star Trek series in a major role in the episode (as opposed to a quick cameo).
Data was basically Spock 2.0.
Stargate Atlantis's Dr. Carson Beckett was originally just billed as a supporting character but ended up in almost every episode of the first season, leading to the producers upgrading him to lead status for the second and third. They then tried to kill him off but fan attachment was strong enough that, in Daniel Jackson-esque fashion, he was brought back as a recurring character.
Spike started out as an Ensemble Dark Horse, than his role got larger as the show went on and he became one of the major characters, which continued when he appeared in Angel. He even got his own miniseries in the After the Fall/Season 9 comics.
The entire ex-Sunnydale cast of Angel. They got their own show.
Jonathan. He was always shown as a generic Sunnydale student and later Ensemble Dark Horse in the earlier seasons. A later season has him return and turn out be a villain. But not really evil. In any case, more important than originally thought.
Anya. Originally a literal Monster of the Week, she was such an interesting character that she got a second episode outing, then was repurposed as Xander's rebound love interest. Joss Whedon did try to write her out on more than one occasion, but kept bringing her back. He waited until The Finale to kill her off.
Melrose Place: Both Marcia Cross (Kimberly) and Heather Locklear (Amanda), with Kimberly stealing the crown in particular with her antics on the show...
LOST: Ben. He was originally meant to be a minor Other who would appear in only three episodes. Extremely positive reception made this extend to eight; then it went to being a series regular (the original leader of the Others was rewritten to be Ben) and one of the show's most important characters. The same applies to Desmond: originally meant to only be in the first three episodes, his popularity made them bring back Desmond, focus the two hour finale on him, and make him a series regular the next year.
J.R. Ewing was only supposed to be a supporting cast member, with the thrust of the storyline revolving around the feuding families. J.R. quickly stole the focus and the producers admitted he had become the breakout character of his series.
Cifff Barnes, Donna Culver, and Clayton Farlow to a much lesser extent as all three were only guest stars before they became part of the cast. Cliff Barnes ultimately appeared in more episodes than anyone else not called J.R. Ewing.
Scrubs: The Janitor became a Breakout Character. He was intended to be a background character to torment J.D. (if the show ended before the first half of the second season, he was going to be a figment of J.D.'s imagination), but the creators quickly (and thankfully) realized how awesome he was and included him in the main cast.
Sylar's popularity conflicted with the fact that season 1 was about killing him, so bringing him back sort of made everything from that season seem pointless and made his presence increasingly unneeded...
In the original publicity for the series, Niki is much more prominent than Claire (see the show's page image). Claire turned out to be one of the show's most popular characters; Niki... not so much.
Claire's stepdad Noah (aka HRG) was originally intended to be a supporting character, but he became the show's most popular non-superpowered human (and appeared in more episodes than anyone else except for the small blonde indestructible one).
The Man from U.N.C.L.E.: An example of a successful Re Tool which made a minor character into a Breakout Character: The original premise had Napoleon Solo working alone, with Illya Kuryakin intended to be only a minor recurring character. Kuryakin struck such a chord with the show's fans, however, that he was raised to one of the leads.
President Bartlet was only supposed to be in four episodes a season, with the show focusing on the White House Senior Staff. But when Martin Sheen's performance wowed the production team, the show was retooled to make Bartlet a main character.
Donna Moss was intended to be a minor character, on level with the other assistants on the show. Bradley Whitford (who plays Josh, her boss) pointed out their fantastic onscreen chemistry to the producers. This led to Donna being upgraded to a main character with her own storylines, and replacing the character Mandy as Josh's main love interest.
Chuck Bass. The show originally gave him a similar role in the book as a date raping villain while also having him as Nate's sidekick. However his astounding popularity has led to him taking center stage to the point where Nate (who is the main male character of the books) seems to have mostly been shoved into the background while Chuck Bass is developed into a more likable character through his relationship with Blair and redemption plotline.
Blair is an even more prevalent example. Early on Serena was the main character but Blair quickly passed her for that title (although ironically Blake Lively became a bigger star than Leighton Meester).
YMMV when it comes to who the actual protagonist of the TV series was - Blair did get a lot of stories and screentime later on, but the series began and ended with a Serena-centred plot. In the books, on the other hand, Blair's indeed more prevalent than Serena.
Sophia Petrilo of The Golden Girls was original intended to be an occasional Drop-In Character, but test audiences loved her so much that she was made an equal to the other three.
Prison Break has Theodore "T-Bag" Bagwell, originally intended to appear in two episodes only. The character was so popular in those two episodes only that he was promoted to main character and appeared in all four seasons.
Also, Sara. To the extend that, when it was rumored that she may not be around for season 3, fans signed a petition to ask for her to continue being a part of the series.
Mahone had become so popular by the end of season 2 that the writers decided not to kill him off like they originally intended to, and keep him alive and locked in Sona.
Orenthal Gibson (Gibby) on iCarly. To the extent that he starred in one of two pilots for a potential spinoff (the one that didn't become a series, mind).
In Season 4 of Supernatural, Castiel was only supposed to appear in a few episodes and then another character was to take his place as Dean's angel guide. However, general consensus decided he'd become the Ensemble Dark Horse. Even though he'd only gotten less than 40 minutes of screen-time at that point, the episode "On the Head of a Pin" (4.16) featured him heavily and 4.20 ("Rapture") centered on his vessel, Jimmy. In Season 5, Misha Collins (Castiel's actor) was promoted to regular status.
Bobby Singer was originally slated to be in only one episode, but circumstances led to him being given more appearances. Luckily the fans loved him. Fastforward to season seven and Bobby is one of the most frequently recurring characters on the show and Sam and Dean both admit to seeing him as the father John never was.
Crowley was originally introduced as a minor villain who joined forces with Sam and Dean during the fifth season back when it was scheduled to be the final. He only appeared three times (once in the middle of the season and twice near its end) but quickly won over the audiences due to how cool, calm, manipulative, and cunning he was and the fact that he was played by Mark Sheppard didn't hurt either. When the series wound up continuing beyond the fifth, he was brought back as a recurring nemesis for the brothers. His popularity increased so much that as seasons went on his role was greatly expanded on even beyond that, and while several recurring characters were either written out or killed off he notably remained, and by seasons eight and nine he became the fourth most important character on the show after the brothers and Castiel, becoming an out and out Villain Protagonist opposing them. Now with the show reaching its 10th season Mark Sheppard has been promoted to a series regular, permanently cementing his breakout status.
Barney Stinson on How I Met Your Mother. He's often seen as the main character, even though it's supposed to be Ted.
Which is actually an example of Fridge Brilliance, since Barney's prominence does interfere with Future!Ted's story about meeting his future children's mother...but it's completely realistic that Ted's life isn't conveniently tailored to somehow be completely thematically compliant with the story of the mother, and Ted can't cut out important parts of his life just because he wasn't the most important figure in those events.
The landmark 150th episode replaced the opening with a gag opening called "How I Met Barney."
Also Troy and Chang. More and more of the series' gags tend to revolve around these three characters.
You could call The Dean one as well. After all, he went from a recurring secondary character in the first two season to a series regular, featured in the title sequence, for Season 3.
Annie's role was also expanded greatly after the first thirteen episodes of the show. Her character underwent a major change, from buttoned-up nerdy girl who had a secondary role at best in most episodes, to becoming a major part of several storylines and one of Jeff's two main love interests. Dan Harmon has said this was done in response to "Debate 109," the episode in which Jeff and Annie kiss, as well as Alison Brie's breakout popularity.
Snooki on Jersey Shore, which is an unusual example considering Jersey Shore is a reality show. The same thing happend with Zlatko in the first season of the german Big Brother.
Guy of Gisborne from the BBC's Robin Hood was never a minor character (and the actor had top billing, behind only Robin himself and Marian until she was killed off), but halfway through the first season the writers develop a serious man-crush on him and his relationship with Marian. By season three, the show may as well be called "Guy of Gisborne."
Sue Sylvester, who wasn't even in the first script drafts until some fairly subtle Executive Meddling and even then wasn't intended as a major character. Importantly, Sue does appear in the very first scene of the first episode, but only as a one-joke character.
Santana is a clear example of a breakout character since she was supposed to be just Quinn's sidekick in the beggining, but by the time of season 4 she had her only storyarch and was living alongside Kurt and Rachel in NY.
Jaime Summers, The Bionic Woman, was meant to be a one time character in a two-part episode of The Six Million Dollar Man, to the point where she died at the end. However, the character's popularity caused the writers to retcon her death and give her a spinoff.
Farscape - Chiana was intended to die at the end of her first episode. Instead, she became a main character for the rest of the show's run.
Scorpius was originally intended as a one-shot villain for the first season finale, but proved such a hit with fans that he was promoted to Big Bad for the next two seasons and eventually became one of the protagonists in Season 4.
Are You Being Served? - The original concept was originally to have Mr. Lucas and Miss Brahms as the leads, being the younger and more "normal" characters. However, the more flamboyant Mrs. Slocombe and Mr. Humphries stole the spotlight.
Phoebe in Charmed. She was really just there in the first two seasons as a background character but fans loved her and in season 3 she was given the main plot arc while Prue was shunted aside and eventually killed off when the actress left the series.
Leo Wyatt and Cole Turner also became breakout characters. However, Cole was eventually dropped in the middle of the fifth season.
Klinger in M*A*S*H started as a one-note bit part in a handful of Season 1 episodes; by the end of the series, he'd been promoted to the main cast, replacing Radar as Company Clerk.
When Law & Order: SVU began it was quite clear that despite the largish cast, everyone was there really as secondary characters to Benson and Stabler. Then people started noticing Fin Tutuola. While the original pair stayed the main focus, Ice-T's Fin had several episodes and even a significant story arc and arch-enemy, sometimes to the point that the main pair barely make an appearance.
In season 14, Raul Esparza came along for what was supposed to be a series of four guest-star episodes. His character, Rafael Barba, became so popular that it became a recurring role and then he was finally promoted to regular for season 15.
Jill Monroe in Charlie's Angels. Despite the fact that she only starred in the first season, she is considered by many fans to be the most popular (for reasons not unconnected with her being played by Farrah Fawcett-Majors).
Frasier Crane was originally supposed to be in Cheers for only a few episodes, but because of his popularity, he became a main character. When the series ended, he starred in a Spin-Off show.
Lilith Sternin also counts as originally she was only supposed to appear in one episode.
To a lesser extent Bulldog, he started off as a guest star, but fans liked him enough that he became a part of the main cast. However, the producers eventually dropped him when he started appearing in less episodes. He continued to appear occaisonally.
Several members of the cast introduced later in the series also became breakout characters.
One could argue that several others from the first season rose in prominence, as well. Carol Hathaway is a prime example, as she was originally scripted to die from her suicide attempt in the pilot. However the test audience (and executive producer Steven Spielberg) enjoyed her so much that she was given a Promotion to Opening Titles in the second episode, became part of the show's supercouple (with Doug Ross, as it turns out), and won Julianna Margulies an Emmy in 1995 (the only one from the entire main cast to earn such an honor). She also earned more nominations than any of the other cast members (at six total, starting out as a supporting female before being upgraded to Lead Actress).
John Carter also received greater exposure as time went on, starting out as fourth-billed in the pilot's opening credits before becoming the central protagonist in the ninth season. However, this may have more to do with the fact that Noah Wyle was simply the only member of the original cast to remain up through then. Even so, Wyle received more Emmy nominations for his work than any cast member besides Margulies, and it's a testament to his character that the closing arc of the series was centered on his return to Chicago, especially as this was 4 years after Wyle departed from the show. "Set the tone", indeed.
Lt. Columbo began life as a throwaway character from an episode of a short-lived anthology series called The Chevy Mystery Show. Here he was played by Bert Freed. That particular episode, "Enough Rope", was later remade as a Made-for-TV Movie titled Prescription: Murder, which marked Peter Falk's debut as the character. Even then, the murderer, played by Gene Barry, was envisioned as a Villain Protagonist with Columbo intended as a supporting character. Instead, Gene Barry's character became simply the first of many murderers to be outwitted by Lt. Columbo.
Kelso on That '70s Show. He began as one of the lower-tier main characters and later surpassed Topher Grace as the star. Seasons 6 and 7 even focused more on his character development than Eric's as he dealt with the trials of fatherhood.
Camille Saroyan in Bones was supposed to die in "The Man In The Cell" but she'd become so popular they kept her.
Brooke Davis on One Tree Hill. She went from not even being in the pilot to slowly surpassing Lucas as the star of the show.
Desperate Housewives: Orson Hodge went from being a one-off character, to a short-term villain, to a main character for 4 seasons.
Zack Morris started off as a supporting character for Good Morning Ms. Bliss with the title character, a teacher, being the actual main character. The series got retooled into being the super popular Kid Com, Saved by the Bell, with Zack being promoted to the starring role, and the rest was history.
Belle and Captain Hook from Once Upon a Time, both of whom started off in secondary roles but were elevated to the central cast due to their popularity.
Cat from Victorious, considering that a) whenever Ariana Grande posts a video of her singing on YouTube, half the comments are about how she should be the show's star instead of Victoria Justice, and b) Cat got her own Spin-Off, Sam & Cat (shared with another Nickelodeon show's Breakout Character). In fact, this led to Ariana becoming a bigger celebrity than Victoria, with more Twitter followers and pop chart success.
Because of the episodic nature of Merlin, guest stars are seldom seen again after the episode in which they appear, however Queen Annis, Princess Mithian and the Dochraid (all introduced in series 4) were popular enough to ensure a reappearance in series 5.
Patito Feo is an Argentine teen comedy freely based on The Ugly Duckling tale. "Patito" is Patricia Castro, an ugly girl, constantly insulted by the Alpha Bitch Antonella. But the aesop broke, and Antonella became far more popular than Patito, and the second season began fully focused on her.
Archie Kennedy of Horatio Hornblower. He was written as a Composite Character and was meant only to appear in the first episode "The Even Chance". However, Jamie Bamber and his portrayal of Archie were so well liked by the cast and crew that he got written into "The Duchess and the Devil" and "The Frogs and the Lobsters", serving as awesome Foil to Horatio's Hero. However, Executive Meddling of The Forester estate would only let other parts of the Mini Series film if Archie Kennedy was to be written out. Not completely unreasonable, since their friendship was changing Horatio's characterization too drastically from the source. Archie was therefore given the opportunity to perform a Heroic Sacrifice to save Horatio in "Mutiny" and "Retribution", and thus immortalized himself in the process. In fans' (and perhaps even the authors') dreams, Hornblower would form the complete hero with Lt. Bush (Hornblower's canonical best friend from the book who appeared in "Mutiny" and "Retribution", and also in the final instalments "Loyalty" and "Duty") as the mind and Archie as the soul of the trio, ŕ la Kirk's complete hero, Spock's mind and McCoy's soul. Even the star of the show Ioan Gruffudd expressed sincere shock that he would have never ever believed it possible to write Archie's character out of the adaptation.
Felicity Smoak on Arrow was originally supposed to be just a tech support agent at Queen Consolidated, but was eventually added to The Arrow's team and Promoted to Love Interest for Oliver replacing Laurel in that regard.
Christopher Ellison as Detective Inspector Frank Burnside in The Bill. He was originally conceived only as a one-off character in the first episode, mainly as an outside antagonist for the main regular characters, but his performance so impressed the show runners that he was invited back to appear in two episodes of Series Two the following year. When original series regular John Salthouse (DI Galloway) left the show following it's third season, Ellison was invited to take his place, and the rest is history. Burnside became one of the characters most associated with the show for his Kubrick Stare and Deadpan Snarker qualities.
Chloe on 24 is a unique example, as when she was originally introduced the fans initially hated her, finding her sarcastic streak that she used to put down her co-workers annoying. One season later and her personality was reworked a bit, making her much more sympathetic while also keeping her deadpan wit from before, but this time around having it focus on characters that deserved it. This new portrayal of her was much more well received, so much that she won enough popularity to return midway fourth season after initially being written out of it early on. Then the moment of truth came where she wound up getting attacked and fighting the attacker off with an M16, which quickly cemented her as a fan favorite. She quickly wound up becoming the second most important character on the show after Jack, so much that she was the first non-Jack character confirmed to return for the sequel mini-series.
Arya Stark, whose journey into becoming a Badass is just so enjoyable to watch, and her current status as already a Little Miss Badass makes her a popular character.
Gannicus in the Spartacus series was written and included in the show prematurely as a result of Real Life Writes the Plotnote Lead star Andy Whitfield was diagnosed with cancer, thus delaying the production . Nonetheless, his cocky but good-intentioned "rock star" personality, coupled with his daredevil fighting style won him fans. By the final season, he has become the Tritagonist.
Popeye - Popeye the Sailor started out as a minor character in Thimble Theatre, which had been running for ten full years before he was introduced. The strip was originally about the adventures of a money-hungry slacker named Harold Hamgravy, who traveled the world in search of riches. Popeye originally showed up as a generic sailor who was hired by Hamgravy for a treasure hunting voyage. He wasn't supposed to show up again after the end of that story arc. Instead, he ended up becoming so popular that the strip was eventually renamed after him. Poor Hamgravy was demoted to minor supporting character status, and to add insult to injury, Popeye even stole his girlfriend, Olive Oyl!
This history is lampshaded in the live-action Popeye movie. As the story opens, Olive has just dumped Hamgravy.
In fairness, though, Hamgravy is kind of a jerk, and only dated Olive because her family is rich (and would routinely dump her for wealthier women, only to come crawling back after they rejected him.) Popeye, on the other hand, is always true to his lady.
The very aptly named Opus of Bloom County and its follow-up comic strips was originally a fairly flat gag character, not intended to ever be seen again after his week-long plot was resolved, but fan reaction quickly led the author to make him the main character of the strip.
Years later, Breathed mused in one of his books about the nature of the breakout character: "You can't design an Opus; they're the sort of characters who come knocking at your door in the pouring rain at 3 in the morning. [The author's] job is to figure out which ones should be let in and allowed to stay."
Funny thing is, he almost accidentally made another one — by making the worst possible deliberate attempt: Bill the Cat. Many long storylines in the later years of the initial strip featured only Bill and Opus, with the rest of the crew having barely more than cameos — such as the 'Deathtongue' stories.
Snuffy Smith. He started out as a one-shot character in Barney Google, a comic about a luckless gambler. A 1934 storyline took Google to a hillbilly mountain community called Hoot'n Holler, where he met Snuffy and his family. Google was only supposed to be there for a few weeks, but Snuffy proved so popular that Google permanently relocated there. The comic was renamed "Barney Google and Snuffy Smith" and Google's part in the strip became smaller and smaller, until he was written out altogether. Despite his name being in the title, Google has only appeared in the strip twice in the past 20 years.
This was actually the second time this had happened to the strip. A decade prior to this, Google's horse, Spark Plug, proved incredibly popular, and ended up becoming the focus of several storylines and a huge amount of merchandise (with the strip temporarily renamed "Barney Google and Spark Plug.") When Snuffy took over the comic, he adopted Spark Plug as his horse.
In the early Peanuts strips, Snoopy acted like an ordinary dog, and wasn't a key character.
Nancy was originally called Fritzi Ritz and about a flapper. Fritzi became Nancy's Aunt Fritzy, and Nancy and Sluggo took center stage.
British newspaper strip Flook (1949-84) featured Flook (a creature) and Rufus (a boy) as main characters. But there was a short period back at the start (before Rufus found and named Flook) when the strip was called Rufus.
Dick Cavalli's Morty Meekle was eventually taken over by (and renamed after) what was originally a minor character, Winthrop.
In the early years of FoxTrot, the strip equally focused on the five members of the family. Come the late 90's, and Jason's pretty much the main character.
The crocodiles from Pearls Before Swine. Zebra originally contacted his predators through letters in the early days of the strip. Wanting to cut out the middleman, author Stephen Pastis had a fraternity of crocodiles (Zeeba Zeeba Eata) move next door. Their complete incompetence in killing Zebra became the comic's new and most popular Running Gag (besides long, confusing puns, of course).
Wrestling's Legion of Doom had many proven stars in it, including both Sheiks. But the entire stable's identity would be completely absorbed by the two least known members at the time of its inception, The Road Warriors.
Eddie Guerrero started out as a guy who would wrestle during intermissions and ended up as one of the biggest stars in Mexico as one half of La Pareja Atómica with El Hijo Del Santo then as part AAA's of Los Gringos Locos.
"Stone Cold" Steve Austin started out as part of a tag-team in WCW with the late Brian Pillman called "The Hollywood Blonds". They eventually part ways and Austin became a singles competitor both in WCW and eventually ECW. When he joined the WWF however, his meteoric rise began after the epic "Austin 3:16" speech he made after winning the King of the Ring tournament in 1996. And the rest, as they say, is history.
While CM Punk has always been an Ensemble Darkhorse, his Career Resurrection in 2011 put him in a whole new level especially when he won his fifth world title, which is also the fifth longest reign in history and the longest since the Hulk Hogan reign of '84 to '88.
Cheerleader Melissa went from valet(cheerleader) to the Ballard Brothers in All Pro Wrestling and semi regular competitor who usually lost to an undefeated streak in Ultimate Pro Wrestling, tours of Japan and the seizing of APW's Above The Law Championship, which she would permanently rename the "Future Legend Championship". Then she became ranked as the best woman in her profession as SHIMMER's champion.
To the annoyance of wrestling fans many years after the fact, John Cena on Thursday Night Smackdown, as his rise to super stardom coincided with the loss of most of what made him a star in the first place.
Jimmy Jacobs, in IWA Mid-South, All American Wrestling and Ring of Honor. Each being a more extreme case than the preceding. Consider he started as a commentator, one could say this of his wrestling career in general.
While Delirious was always fairly important to the angles of his starting promotion, Gateway Championship Wrestling, in Ring of Honor he was little more than a jobber for higher who got a long term deal because the RoHbots took an unexpected liking to him. Then worked his way out of jobberdom to feud with Adam Pearce's Hangmen 3, Austin Aries and his so called Pantheon of gods and became the aforementioned Jimmy Jacob's enforcer in Age Of The Fall.
However briefly, Dolph Ziggler was a main eventer and World Heavyweight Champion after starting out as Kerwin White's caddy and a cheerleader in the spirit squad.
AJ Lee went from loser of NXT season 3 and borderline jobber to spotlight stealing general manager of Monday Night Raw and then longest reigning divas champion.
Hey, man, this is Donnie Baker. I was a know-nothin' redneck that owned a boat and worked as a stockboy under that dumbass Randy. Then I started callin' The Bob & Tom Show. Now the chicks can't keep their hands off my pork rind. I swear to God they can't.
Karl Pilkington, from The Ricky Gervais Show, for a real life example. Originally the show was just a vessel for Ricky Gervais and his partner in crime Stephen Merchant. Then they discovered the machinations of their producer's mind and the entire thing changed gear. Karl Pilkington quickly became the focus of the show, and his thoughts (and mad stories) have since been compiled into books, and even a TV series.
David Alan Grier when he's a guest. Particularly his impression of R and B singer Teddy Pendegrast, which usually involves a skit of him coming into the studio to lay down backing vocal tracks (with Adam acting as producer) and him going off into obscene sexual tangents.
Recently, comedian Jo Koy's "Bung Lu Soo" character (aka "The Rooster"), who has evolved from his "generic Asian guy accent" bit. He's constantly trying to join old 70s bands and goes on weird tangents. When he's not trying to join musical acts, he's the host at PF Chang's, not allowing Adam to sit down despite his reservation.
Jo seems to have another hit on his hands with "Brown Sugar" a literal box of brown sugar trying to live in the pantry, only to be denied by the other spices due to his "ethnicity."
Big Finish Doctor Who has Charlotte Pollard the Edwardian Adventuress. She was the 8th Doctor's main companion in the monthly audio series and ended up getting her own spin-off.
Trouble was intended by PeabodySam to be a one-off character who would only appear in a very short scene. Trouble ended up becoming popular enough to become Rex's personal Lancer. When Trouble was suddenly subjected to Chuck Cunningham Syndrome, other players eagerly awaited his return. They ultimately got their wish when Trouble came Back for the Finale and was given a Dying Moment of Awesome.
Kat was introduced by Jackson Lake as an Affirmative Action Girl. As a response to her unexpected popularity, Kat was elevated to a higher level of prominence and given far more character development, especially starting with the Goo CavernsStory Arc.
Dr. Alan Pierce was first brought in as a seemingly random extra who existed for no other purpose than to heal Zenna after she got into a nasty accident. Not only did he go on to become a major character in the RPG and one of Atton Rand's most popular characters, but his popularity also led to the Dino Attack Team's medical wing being brought to the forefront and being a focus for drama as opposed to simply a place for wounded agents to be healed.
A number of Red Shirt characters, such as Hertz and Zelda Frodongan, were able to survive and graduate to Mauve Shirt status before ultimately becoming important members of the cast thanks to their popularity.
Luigi started off as a simple Palette Swap of Mario, and became perhaps the biggest Ensemble Darkhorse of the entire franchise. He got a game of his own, and while he remained out of the main series in the Nintendo 64 and Gamecube era, he came back in Super Mario Galaxy, earning bigger roles in the main series as it went on.
Wario was created for Super Mario Land 2: 6 Golden Coins to symbolize the development team's displeasure with developing for a series they did not create. However, the guy became so popular that he ended up getting his own Spin-Off series, Wario Land. And if that wasn't enough, that series became so popular, Wario received another spin-off series called WarioWare, which has typically become one of Nintendo's flagship franchises for showcasing each new console's unique features. Not bad for a one shot Evil Counterpart/Rival born of a Writer Revolt.
Illidan Stormrage appears in only one level and one cutscene in Warcraft III. The Addon Frozen Throne and the World of Warcraft expansion Burning Crusade are all about him being Bad Ass. The latter, by turning him from an Anti-Hero to an Omnicidal Maniac, tried to take the edge off of his popularity but was widely considered discontinuity instead.
Saurfang was just a quest-giving NPC among thousands in World of Warcraft, until the fanbase made him a Memetic Badass. Realising how popular he was, Blizzard subsequently made him a veteran fighter in all three wars, commander of a coalition army, right-hand to the warchief, retroactively right-hand to the former warchief, second in command in the Northrend campaign, and if he hadn't lost his son, he'd probably be warchief now.
In Warcraft III: The Frozen Throne, Vol'jin was a witch-doctor (a very weak, support-only unit) who gave quests to the real heroes of the campaign (Rexxar, Rokhan and Chen) so they could save his people. In World of Warcraft he doesn't do much more at first, besides asking for help to deal with a level 10 mob. Several expansions later, he's leading the rebellion against Garrosh Hellscream, had a novel written about him, and finally becomes the new Warchief of the Horde (and the first non-orc to do so) after Garrosh is deposed.
Touhou has a lot of characters, some of them more popular than others. Probably the most striking example is Cirno, the lovable Baka of the series. From her lowly start as a Stage 2 Boss, her popularity grew to the point where she received her own game: Touhou 12.8: Fairy Wars
Some say Zero, Ensemble Dark Horse of Mega Man X is this, seeing as he was a supporting character in his first appearance, and promoted to main character status as the series progressed, especially getting his own series that further showed his awesomeness. There's a twist, though: Zero was supposed to be the main character (in other words, Mega Man X himself), but was "demoted" because his creator, Keiji Inafune, was told that Zero looked too different from the original Mega Man.
Aigis from Persona 3 is given the spotlight plenty of times throughout the course of the game, but no more often than anyone else in the main cast. But she was such a hit with fans that she was made the main character of the game's direct sequel, The Answer.
Rather surprisingly, as although she is of course an excellent character Akihiko, Shinjiro, Mitsuru, Ken, and Jin are all much more popular.
Naoto from Persona 4 also proved popular enough to get a spinoff manga.
The Rabbids from the Rayman series. Most people don't know about Rayman, while the Rabbids have their own games.
Half-Life's 'Barney' Security guards, not only did they get an expansion pack (Blue Shift) where the player takes the role of one, but they are personified in the next game by one of the support cast (Barney, arguably only second to Alyx as a player companion).
In Super Robot Wars Original Generation, the canon route is obviously Ryusei Date's. But Kyosuke Nanbu proved to be way too popular that he and his girlfriend Excellen Browning are promoted into main characters by the second game.
A rather surprising example is Tetsuya Tsurugi. In the first Super Robot Wars Alpha, hes basically a character who complements Koji's role and following strictly into the original show's storyline. And then he proceed to become the Main Character of Alpha Gaiden. Yes you read that right, a non Original Generation character become the Main Character.
In Final Fantasy III, the Big Bad was Xande, an Evil Sorcerer who wanted to destroy the Crystals to regain his lost immortality by stopping time. The final boss that appeared when he died, Cloud of Darkness, was a Giant Space Flea from Nowhere that was your typical Omnicidal Maniac. But the Cloud of Darkness was a more interesting, climactic boss with a striking design, which, combined with the game being a vague memory at best for most fans and the vagueness of the plot, meant that she was much better remembered. This became official with Dissidia: Final Fantasy where the Cloud of Darkness is III's sole villain representative, even after the sequel adds to the cast.
Gilgamesh, who was a villain, has the most appearances in Final Fantasy games overall. Dissidia 012 even confirms the longtime fan theory that, unlike most other recurring characters, it's the same Gilgamesh in every single appearance.
Laguna Loire from Final Fantasy VIII is a Hero of Another Story (an in-universe "Dream World" sequence) and can only be played five times. However, he became a very popular character due to his mature, yet light and humorous storyline/dialogues.
In Final Fantasy XI, Shantotto started off as just a rather random NPC with a series of somewhat humourous quests and being involved in the black mage quests. Then she made a cameo towards the end of the Windurst missions and some of the Chains of Promathia missions. Then she was a major character in Treasures of Aht Urhgan and appeared in some minor events (such as being the main enemy in a fight against some of the female characters). Then she represented the game in Dissidia: Final Fantasy. Then she got her own storyline expansion centered just around her.
In the convoluted mess that was Sonic the Hedgehog (2006), it is Shadow and Silver, not Sonic, who ultimately have more ties to the plot (in Silver's case, he hails from the Bad Future, so of course he'd be heavily involved).
And before Shadow, in the 90s there was Knuckles. Much like Shadow, he initially showed up as an antagonist to Sonic, and then found himself upgraded to being a member of the main trio and on the 32X he even had his own game. This even extends to the Archie comics where Knuckles had his own spin-off book that at one point almost surpassed Sonic's in popularity.
In the Castlevania series, most of the games focus on the efforts of the Belmont family to do away with Dracula once and for all. In 1989's Castlevania III, we are introduced to Alucard, the Dark Lord's prodigal son. Here, Alucard didn't really amount to much, seeing as he was a generic-looking vampire who threw weak fireballs. However, when he resurfaced eight years later in Symphony of the Night (the series' re-visitation into the now iconic Metroidvania style and widely considered to be the Magnum Opus of the series alongside Rondo of Blood), revamped as a badass, stoicBishōnen with a slew of nifty tricks and weapons (as well as strong, yet conflicting ties to both his father and mother), he instantly became so popular that he's now just as synonymous with the series as the Belmonts, Dracula, and Death are. It doesn't help that he's basically immortal, thus meaning that he's the sole recurring hero with the greatest chance to be in any game should his presence be required (i.e. his appearance in the Sorrow games as Genya Arikado).
GLaDOS from Portal. She was originally intended to only speak in the Relaxation Chamber at the start of the game; playtesters liked her so much, Valve decided to use her throughout the game. She became synonymous with the Portal franchise and was even the final boss of the first game.
Georg from Suikoden II was just one of the characters of the 108 needed to be recruited. However, his backstory by having Richmond investigate him proved to be popular to fans so much that in Suikoden V, set a few years before Suikoden I, Georg became one of the main characters. The rest is history.
In Mass Effect, it was obvious the spotlight was supposed to be on your two human squadmates. They both got lots of screentime, were the major romance options (Liara sort of played second fiddle), and were your first two partners. Instead, fans centered on Tali, Garrus, and Wrex. In the sequel, the three of them get lots of screentime and plot relevance, while the surviving human is Demoted to Extra. By the third game, both Garrus and Tali are easily in the category of "top five most important characters in the entire series", as they're the only characters who are squadmates in all three games and Shepard calls them his closest friends. In the third game, Garrus and Liara have the most dialogue with Shepard by far, even though the former can be dead at that point in the story.
While not more popular than the main characters, Murray the Mighty Demonic Skull was only intended to be in one scene of The Curse of Monkey Island. The beta testers liked him so much that the developers added him to several other scenes and subsequent games (as a bouncer for Planet Threepwood in Escape from Monkey Island and locked up in a treasure chest inside a giant manatee in the third episode of Tales of Monkey Island).
Murray: ...and the forces of darkness will applaud me as I STRIDE through the gates of Hell carrying your head on a pike!
Guybrush Threepwood: Stride?
Murray: Alright then, ROLL! ROLL through the gates of Hell... Must you take the fun out of everything?
In most games, the child that the protagonist is saddled with protecting is despised. The developers of the The Walking Dead played their cards right with Clementine, however. She's one of the most popular characters in the game.
It's hard to remember, but Pikachu wasn't the original mascot of the Pokémon franchise. Clefairy was supposed to be. The Anime of the Game had Pikachu be the starter of the protagonist instead of one of the original three, and when the series took off so did Pikachu. Pikachu evolved into the series mascot, even getting its own game in the form of Pokemon Yellow Version, and never looked back.
Also worth noting that every gen tends to have it's own Breakout Pokemon that end up representing the gen as whole:
Generation 1: Charizard, Pikachu, Jigglypuff, Mewtwonote Charizard was the fan favorite starter, and thanks to popularity poll results and merchandise sales, can be argued to be the most popular Pokémon in theUnited States. It was one of two Pokemon to get two Mega Evolutions in X and Y, and was also depicted as the main Pokémon in Pokémon Origins, the first animated Pokémon feature directly aimed at the Periphery Demographic. As noted above, thanks to the initial popularity of the anime, Pikachu was made into the official mascot of the franchise. Pikachu's popularity even warranted a Recursive Adaptation, Pokémon Yellow. During the early days of the franchise, Jigglypuff was the second most popular Pokémon in Japan - again, due to the anime - and was one of the most prominent recurring characters in the anime, although its popularity has waned since then. Like Charizard, Mewtwo got two Mega Evolutions and ranks very high in popularity polls. Starting off as a Bonus Boss in the original game and being the star of Pokémon: The First Movie led to Mewtwo also becoming one of the most popular pokemon in the franchise.
Generation 2: Lugia note One of the two Legendary Mascots for Generation 2, both Silver and Soul Silver ended up becoming the best selling versions. Lugia's popularity led to it making several extended appearances in the anime, and even served as the focused Pokemon of the second movie.
Generation 3: Blaziken, Rayquaza note Although not to the level of Charizard, Blaziken ended up becoming the most used starter of the third generation. Blaziken's popularity led to the game developers into creating twoExpy starters in the form of Infernape and Emboar. Blaziken also was the first starter after the originals to get a Mega Evolution in generation 6 (and as an event, at that!). Rayquaza, like Charizard, ranks high in popularity polls and was voted as the most popular version mascot in a Japanese poll. It got quite a few gratuitous appearances across the franchise from late 2011 to early 2012, including as Oda Nobunaga's strongest Pokémon in Pokémon Conquest.
Generation 4: Lucario note Lucario's popularity exploded upon release, quickly overshadowing the starters of the gen as the most popular pokemon. Lucario became the focal pokemon of the 8th movie, a gift pokemon in every subsequent game released after it's introduction, and even given an expy in the form of Zoroark.
Generation 5: Zekrom note Similar to Lugia before it, it's appearance on the cover ensured that the White version ended up becoming the best selling version. Like Rayquaza, Zekrom was one of Oda Nobunaga's most prominent Pokémon in Pokémon Conquest, and is the closest one can get to the main Pokémon of the game. Zekrom proved to be so popular that Mega Charizard X ended up being modeled after it.
Generation 6: Greninja note The newest entry, Greninja, became the fan favorite starter of generation 6, exploding in popularity right out the gate.
Five characters on this list (Charizard, Pikachu, Jigglypuff, Lucario, and Greninja) are playable in Super Smash Bros. for 3DS/Wii U, while Mewtwo was in Super Smash Bros. Melee.
The Edutainment series Jump Start has an example not precipitated by popularity among the fans (because JumpStart kinda doesn't have a fandom). Frankie the dog was always a relatively important character, but circa 2001 he was made the main character and mascot of the entire series (for no clear reason except that they wanted a main character). Nowadays, it has intensified - it seems like Frankie is much more important than any of his friends in the MMOG.
The Fire Emblem series has Malice, the tomboyishPunch Clock Hero sporting an Eyepatch of Power who first appeared in the obscure downloadable title BS Fire Emblem. She quickly became the most popular character in the spinoff, and was later incorportated into the main story of the Mystery of the Emblem remake, complete with a bigger role in a DLC chapter that expanded her backstory considerably. She went on to appear in Awakening as a Spotpass-distributed legacy character, "representing" Mystery of the Emblem despite not actually debuting in that game! And there she finally gets to be a female Mercenary again, to the rejoicing of many fans (for those not in the know, female members of that class are extremely rare throughout the series, so the few that exist generally receive immediate Ensemble Darkhorse status).
One of the Waddle Dees in the Kirby series has turned into his own character—he's known across the fanbase as "Bandana Dee" because of his signature blue bandana. He originally appeared as a minor opponent in the Megaton PunchKirby Super Star minigame, but later went on to become the joke boss in Kirby and The Amazing Mirror. He would end up being very popular with the fans after that, so the developers followed up by making a major character in Kirby Super Star Ultra in the Revenge of the King episode, and eventually became Promoted to Playable in Kirbys Return To Dreamland, with his primary ability being the spear and being able to simply jump continuously rather than float or fly with wings. Since then, he's been a core part of the series.
Kotori Shirakawa was one of the heroines in Da Capo, though both Nemu and Sakura were more important characters to the 'real' plot of the story. However, Kotori proved to be extremely popular and landed not only a clear expy in the sequel but also numerous fan discs and side stories to satisfy all of her fans.
Ray and Roast Beef from Achewood. Originally two of a trio of cats (along with Pat) who fancied themselves "the dirtiest dudes in town" and basically existed to be a bad influence on Phillipe. So interchangeable were they in the early years that Beef was billed simply as "the other cat," notable only for being "not Ray, and not Pat." But soon the three of them began to develop their own personalities, the trio became a duo (with Pat evolving into a sanctimonious vegan) and the strip began to revolve around the friendship between laid-back Ray and eternally depressed Beef.
The little blue thing in Something Positive was simply a one-off joke for Life with Rippy until...well...fans started liking the bastard. He'd eventually become Kharisma's imaginary "NEW FRIEND!" What the hell were the fans thinking?
Probably the same thing they were thinking with Rippy himself...who was a one-shot one-panel gag in S* P, and he'd eventually get his own gag series.
Loopy church-girl Joyce stole the spotlight in Roomies!, with most storylines centering around her. Willis tried to write her out by having her inducted into secret alien-fighting organisation SEMME, but it backfired. Once SEMME was in the picture, Willis found it more interesting than the college life premise, and It's Walky! was the result. She then stole the spotlight again in It's Walky!, as the strip mutated from being primarily about Walky to being primarily about Walky and Joyce's relationship.
Both Mike and Robin were relatively minor characters in It's Walky; Robin was only introduced halfway through, and while Mike was there from the beginning, his role was later reduced by transferring him to a different squad. However, come Shortpacked!, both are members of the primary cast—in fact, Willis knew his next project would be Shortpacked, and decided to lay the groundwork early, creating Robin to spin her off and deliberately killing Mike to cause confusion when he reappeared. (come Dumbing of Age, emphasis on both is heavily reduced, Robin moreso than Mike) .
Fox and Collin from Friendly Hostility were originally minor characters on the author's previous webcomic, Boy Meets Boy. Now that Friendly Hostility is over, the writer's started Other People's Business which has Leon, a minor character from Friendly Hostility as a major character, and Collin reduced to the background.
Said intermission is canon - the Midnight Crew are the exiles of the Trolls, who are Breakout Characters in their own right..
They also have counterparts in the kids' session. Spades Slick's counterpart / alternate universe past self, Jack Noir, ultimately became the Big Bad.
In Dead Of Summer, the integration of The Protomen was secondary, as originally, the characters in Book 2 were going to be just a group of people who lived underground. The Protomen's willingness to be in the comic, however, suddenly gave these people names and faces. They soon became major characters, and have drawn many fans to the site for the sole reason that they're the Protomen.
Zexion in Ansem Retort became increasingly more popular in Ansem Retort, to the point that Season 3 revolved entirely around him. Nearly everything in the comic ends up focusing on him and/or Axel
Arthur the duck and Gramp in Sheldon. Weeks can go by without seeing the title character.
Zig Zag from Sabrina Online. A decade after her introduction, she's gone from "just Sabrina's boss" to being just as prominent a character as Sabrina herself.
Yeah, but Zig Zag was invented by Max Blackrabbit, a friend of Sabrina creator Eric Schwartz, and was already established with a backstory and porn career when Schwartz asked to use her. She's more of a permanent crossover character, and was pretty well destined to rub up against Sabrina in the way that she does.
Kel from Rogues of Clwyd-Rhan. She first appeared as indentured servant to the Green Knight, joined the Rogues when they overcame him, and spent a year or so snarking in the background (with stringy hair) before growing a personality (and nice head of ginger locks), and becoming one of the principal characters.
HelmetedAuthor. Did you know that he wasn't originally even a character to begin with? When he first appeared, he was supposed to be just THE Authorwith a helmet. The Dave just decided to give him his own comic. Helmeted Author Quips were so popular that Helmutbecame the Big Bad of the series, eventually possessing Bob.
Mynd, Chadling and Mike. They were originally just villains that a fan requested. However, Chadling betrayed Mynd and after the storyline, all three became so popular that Mike became the narrator of the Second Party. Later he was resurrected by Mega Man and Bass. Then he got an Evil Counterpart from Evil Overlord Mike AKA Ninja Ned. Mynd himself became one of Bob's three evil minions.
The Slender Man took off by means of this trope. Originally, there was (and still is) a thread on the Something Awful forums devoted to photoshopping normal photos with ghosts or monsters hidden somewhere in there, with one intent being to dupe real life paranormal organizations. Eventually, one member posted two photos of a tall, thin man with no face who had tentacles instead of arms. Slendy gradually took over the thread because he was, more than any of the other ghosts and monsters, genuinely terrifying, and thus, a legend was born.
Annoying Orange sprung forth two adorable characters Marshmallow and Midget Apple, who were both introduced as miniscule, supporting characters in their first videos (esp. Midget Apple who only got one line), but grew to become two of the most iconic, beloved characters of the series.
In The Lazer Collection, Doctor Octogonapus made a single appearance. The sequel has him making several appearances, and in the third, there's an actual storyline and he's the antagonist.
Catbug only appeared in three episodes of Bravest Warriors' first season, but by the season's finale he's easily the most popular with its fanbase. And with a seemingly expanded role in the upcoming Season 2 and a web short just for him, the folks at Cartoon Hangover are very aware of this.
It has Lydia Bennet. In the book this is inspired of, she is shown as an irresponsible Hormone-Addled Teenager who jeopardizes her family's future and her sister's chances of happiness for a hunk. The series highlights both her Freudian Excuse (her mother is obsessed with men and thinks that no happiness or self-worth could be really found without a loved one, and she receives no attention from her Aloof Big Sisters) and her more sympathetic traits (she's almost in love with the things she has a passion for, making her vibrant and genuine, her talent for getting things to go her way is both innocent and hilarious and she has no idea of what she is doing). Plus, she is a Fiery Redhead played by the adorkable Mary Kate Wiles. On the flip side, she becomes The Woobie. She was very popular with the fans, but she was obviously an interesting character to the writers who gave her lots of opportunities to shine. She even had her own spin-off vlog.
Bernie Su, one of the head writers and directors of the show, frequently described Charlotte Lu as his favourite character. Charlotte Lucas of Pride and Prejudice was voice of reason and close friend to book Lizzy, but her role was made much more important in the vlog.
Woody Woodpecker: Woody first debuted in the Andy Panda short "Knock Knock" but ended up becoming so popular that he immediately spawned his own series of shorts, quickly eclipsing the cutelittle panda in popularity.
Donald Duck upon his second appearance, (and his first on a Mickey Mouse cartoon) where he effortlessly steals the picture away from everyone. It wasn't long before he became much more prominent on the cartoons than the Mouse himself....or pretty much every other Disney character.
Timmy in South Park was initially intended as a one-shot character, but proved so popular that he was brought back again and again, and even made it into the opening in series six, after the departure of Kenny. However, after his brief moment in the sun, he quickly receded into the background again. These days, he is hardly used at all anymore.
Jimmy ultimately proved to be the more popular differently-abled character, likely because he can say more than just his name and a few other catchphrases.
Butters went from being a background character to being the fifth most prominent character on the show. Then there's Randy Marsh, who went from a geologist simply named "Randy" to "Stan's dad" (thus giving him a recurring role) to arguably being right behind Butters in terms of prominence.
If you guess that the next episode will be a Stan & Kyle, Kyle & Cartman, Cartman & Butters, or Randy (& maybe Stan) episode, you will be right 80% of the time. The remaining 20% are episodes about the boys as a group or the odd supporting character.
GIR in Invader Zim. He is certainly the favorite among the majority of fans, even to the point that it really annoys his voice actor when fans ask him to do something like sing the Doom song. And aside from that, Nickelodeon still makes lots of GIR-themed merchandise, and now they've reached the point where they have to make up new quotes just to put on T-shirts.
Remarked on in the script reading for The Trial.
"Back on Earth, mankind has reconstructed the planet. Everything is in GIR's image."
Richard Horvitz: Jut like Hot Topic!
While Animaniacs was always intended to be a series of shorts with many different characters, the incredible popularity of the Pinky and the Brain shorts led to them appearing in significantly more episodes than the other skits. They were also the only ones to spin-off into their own show.
The Simpsons ruthlessly parodied this concept in an episode where Bart accidentally becomes a cast member and breakout star of the Krusty the Clown show. The Simpsons are breakout characters from The Tracy Ullman Show.
Although the Simpson family are the main characters, the early seasons focused on Bart until Homer replaced him later on.
Quagmire is an odd example. Arguably more popular than Cleveland, he started out as one of many generic friends of Peter. However, his kinky nature made him too difficult to really market and Cleveland was instead chosen for the spinoff. This was eventually lampshaded in an episode of The Cleveland Show:
Quagmire: Well, they made it through the whole season. Now can I have my own show, Peter?
"The Music Meister" was popular before the episode officially aired, he even has a tropenamed in his honour.
Xiaolin Showdown: Raimundo pretty much stole the show from Omi, being the character with the most development, and if anyone still wasn't sure of his status as the new main character, the finale proved them wrong.
Shego from Kim Possible started out as a flat sidekick to Dr. Drakken, got a personality while being inserted into the pilot after the creators heard her voice actor Nicole Sullivan, and she and her dynamic with Dr. Drakken became so popular that they became the most featured (and fleshed out) villains in the series.
Metalocalypse: Charles Foster Ofdensen wasn't even in the first episode and remained a relatively minor character for the first few episodes of the show, but slowly became not only a great straight-man foil for the band but became an incredibly popular character in his own right as well as a genuine member of the main cast, leading up to several spotlight moments in Season 2 and culminating in his Heroic Sacrifice at the very end of the S2 finale. He gets better.
Darkwing Duck character Morgana Macawber ("Macabre") and her weird undead family were introduced as a set of villains who disappeared (for many years, within the context of the episode) when their house vanished at sunrise at the end of the episode. Morgana's family was never seen again, but she herself returnedwithout explanation to play both a villain and later a hero, developing into a series semi-regular and Darkwing's Love Interest. Similarly, villain Negaduck was originally an Evil Twin of Darkwing's who was accidentally created from his own body and was re-absorbed back into him at the end of the episode. Series creator Tad Stones liked the character so much that he was brought back to be Darkwing's Arch-Enemy and was eventually established as being another Darkwing from a parallel reality called "the Negaverse". When the writers asked how they should explain Negaduck's return following his "death" in his debut episode, Stones replied, "What do you mean, 'how'? He's back. We did it."
Helga Pataki in Hey Arnold! After an amazing amount of character development for her and flanderization of Arnold, many may argue that by the end, she was the true protagonist of the series.
Tigger was a secondary character in the original Winnie the Pooh books, appearing only in the second book, The House At Pooh Corner. In the Disney adaptations, he got bigger and bigger roles until he ended up as the franchise's main star apart from Pooh himself. He even gets top billing in My Friends Tigger and Pooh. Not to mention his own movie.
Ironically The Tigger Movie also began the expansion of simiarly minor character Roo's role, with him gaining much larger spotlight in later movies and also his own Direct to DVD movie. Pooh's Heffalump Movie also arguably featured Roo more as the main protaganist than the title character.
Tinkerbell being practically the second mascot of Disney after Mickey Mouse (appearing in many commercials and in the studio's Vanity Plate), has become a Breakout Character and now stars in a series of her own.
And if you're a guy, Grumpy's got you covered. It seems the Disney characters with the the most attitude tend to be breakout characters.
Lugnut and Bulkhead from Transformers Animated have both become favorite characters in the larger Transformers canon. The former has been retconned into the G1 animated movie, while the latter has become a main character in Transformers Prime.
Before them came Sunstorm, a random yellow background Seeker from the original cartoon that eventually gained characterization in the comic continuity.
Roger from American Dad! originally started out as an alien who lives with the Smith family as well as being forced to stay within the house and didn't have much major importance to the plot. Later in the series, he was more outgoing through the use of disguises and is one of the more prominent characters. Recently, he's the second most prominent character after Stan, and is now one of the most popular characters on the show.
I Am Weasel started out as a supporting act to help compliment Cow and Chicken. The shorts were eventually spun off into an independent series that even outlasted C&C.
The Red Guy was so popular on Cow & Chicken, he started appearing on I Am Weasel starting in the second season.
Perry the Platypus is this for Phineas and Ferb. Merchandise is made in his likeness in buttloads.
A couple of Kablam! examples include Loopy and Prometheus and Bob. Not only have they lasted through the entire show, but Life With Loopy had a Kablam! special dedicated to it while Prometheus and Bob was nominated for the show's own Kablammy award (Which was won by ALN) and was planned to be adapted into a film (It was canceled due to lack of interest).
Discord first appeared in the "Return of Harmony" as essentially a chimeric version of Q, and was so Crazy Awesome that many fans couldn't help but fall in love with him. Although Taken for Granite at the end of his debut, he was revived in season 3 to bealmost successfully redeemed by Fluttershy, and was promoted to recurring character in season 4.
Princess Sally Acorn, from Archie Comics' Sonic the Hedgehog and Sonic the Hedgehog, had more of a supporting role in early Archie but is arguably as prominent a character as Sonic himself later on. This is even more evident counting her earlier background as a minor captive in the games.
Terra on Teen Titans was meant to be killed off at the end of Season 2, but fans kept asking for her return and later got their wish, though they were not happy about it since said episode had a Downer Ending and was the last episode of the series.
Raven's breakout popularity on the show has actually affected how she is written in the comic, with the intent of bringing her closer in line with Tara Strong's portrayal.