Absinthia: Ruthea was an optional boss in Celestial Hearts with little impact on the main story. In this game, she's an important person in Freya's backstory as Freya's ex. She's also a Guest-Star Party Member in a flashback, in the Typh Village sidequest, and in Lilith's final phase.
While he's not technically a person per se, the Blue Badger. He goes from a little plush toy in the first game, to the police mascot and key plot device in the DS remake's extra case, and by Ace Attorney Investigations he's got an entire family and a stage show as well as being the Gatewaterland Mascot.
Gregory Edgeworth. Besides being the deceased father of one of the main characters, and the victim in the DL-6 Incident, he doesn't get much fame... that is, until you play a case as him in Ace Attorney Investigations 2.
The nameless chief prosecutor who gave von Karma his penalty right before the DL-6 incident in the first game appears in AAI 2 as an important antagonist.
The Addams Family game for the TurboGrafx-16 stars Tully Alford, of all people, as the main character. Confused? Tully was the villainous Addams family lawyer in the 1991 movie (played by Dan Hedaya) making him an example of a Villain Protagonist, as well.
The video game adaptation of And Then There Were None promoted the boatman from a minor character who drops off the story's main cast on the island and leaves, to the protagonist who investigates the killings (also replacing the original boatman, Fred Narracott, with his brother Patrick). A necessary case, as putting one of the original ten characters under the player's control would break the novel's premise that all ten are both suspects and targets.
The Nintendo GameCubeAnimal Crossing has a feature where, if you connect a Game Boy Advance to your console, then you can access the island, which has its own set of unique villagers. Later games removed the islandnote New Leaf has an island, but it's a Minigame Zone with online multiplayer and promoted many (though not all) island villagers to regular villagers.
From the Assassin's Creed franchise, Initiates identifies Gavin Banks and Harlan T. Cunningham as previously unknown Assassins heard speaking in Revelations and Brotherhood, respectively. Their appearances in those games are expanded upon and they became central characters to Initiates own narrative.
ARK 2: In the previous game, the Brachiosaurus was simply an alternative skin for the Brontosaurus in the ARKaeology event. Here, it's officially one of the game's creatures.
Astra Hunter Zosma: Captain Scuttlebone was a postgame boss in Brave Hero Yuusha, but in this game, she gets a character arc as the boss of the fifth stratum.
One of the companions, Voghiln the Vast, previously showed up as a gladiator who players could briefly fight alongside, but who had no real plot role.
Skie is a completely optional, superfluous (one of the already many thieves and she is also lackluster in that) and easily missable companion in the first game, since she can only recruited in the final chapters of the game as part of a side quest of another at best average character, Eldoth, whom you meet in mid-campaign when your party is already established. Comes the Enhanced Edition with the Siege of Dragonspear expansion, and Skie, while not being anymore recruitable, acquires a major role at the end of the campaign that is pivotal for the story.
Thanks the the experience-based promotion system that Battle for Wesnoth uses and the ability to recall units from previous battles onto the current map, any unit with multiple promotion tiers can go through this in the campaigns, going from "just another generic recruit" to a strong, powerful, and pivotal member of your army.
The Binding of Isaac: Greed started out as just another one of the Seven Deadly Sin bosses, just with the trait of ambushing the player character in Shops and Secret Rooms. By Afterbirth, he got his own themed mode and became the only one of the Sins with a player character counterpart in the form of the Keeper. A much bigger version of him also serves as the Final Boss of his self-tited mode.
Butt-Monkey Bang Shishigami was treated as a joke by a wide variety of characters, the sole exception being Hakumen. However, an offhand comment by Rachel about an inactive Nox Nyctores turned out to be more than met the ear as Bang ground his ass off and turned into a Minor Major Character as a result — as Chrono Phantasma is moving into Ikaruga, the fans are undoubtedly going to be quite pissed if he doesn't get a significant share of the spotlight this time around. He may still be an over-the-top anime ninja pastiche with a loud voice and a scruffy face, but that's why he is a beloved.
Makoto Nanaya was little more than a bit of Noel, Jin and Carl's memories in CT, but she had significantly changed from the Fun Personified role by the time she arrived in Kagutsuchi in CS. A rumor passed around the internet that she was made DLC in vanilla CS due to plot relevance rather than popularity (not that she isn't popular — far from it), but the full extent came out bit by bit up until Extend — there are reasons why Slight Hope in totality is considered an episode of badassery, and with that degree of involvement in the main story, she is clearly not going away.
Tsubaki Yayoi, Valkenhayn R. Hellsing, and Relius Clover also got the relevance treatment — mere mentions or brief appearances turned into characters with full-blown stories behind them and connections to the plot at large.
Kokonoe is a subversion, since she was plot-important even before she became playable. There was still much rejoicing when she did.
The protagonists of Borderlands: The Pre-Sequel! consist of characters who appeared in previous games as either bosses (Wilhelm, Nisha) or questgiving NPCs (Athena, Claptrap). The exceptions are "Jack" (while a Handsome Jack impersonator was in Borderlands 2, it's unlikely to have been the same character) and Aurelia (whose estranged brother Sir Alistair Hammerlock was a quest-giving NPC instead).
The Capcom vs. series ascended many minor characters from both Capcom and the rival companies:
Yami is the final boss in Tatsunoko vs. Capcom, and the given explanation why all the characters in that game meet up together. Protagonist Amaterasu had to wait until Marvel vs Capcom 3 for her first appearance.
Eagle and Maki, two long-forgotten Street Fighter and Final Fight characters, ended up appearing in Capcom vs. SNK 2 as playable fighters, and they, along with Yun from Street Fighter III, got ported over to the GBA release of Street Fighter Alpha 3 as unlockable characters. The PSP version keeps them, as well as Ingrid, from Capcom Fighting Evolution. On the SNK side, the game also brought back Ryuhaku Todoh, a character who had only ever been playable in the first Art of Fighting before being supplanted by Kasumi, his much more popular daughter.
This also applies to others like Dan Hibiki (who started off as a throw-away character in one piece of artwork) and Sakura (who was originally a Joke Character and got her own manga).
Street Fighter Alpha 3 introduced the plot point that Cammy was one of a long line of female clones/doppelgangers created by Bison, complete with a lineup of twelve of them, each named for a month in a different language. Only Juni and Juli received any attention at the time... until over fifteen years later, when Ultra Street Fighter IV gave sudden attention to another one, Decapre. She not only became playable and got her own storyline, but later had a role in Street Fighter V's story mode as well. Said story mode also featured exclusive boss battles against six Dolls who haven't been playable yet: Enero, Février, März, Aprile, Satsuki, and Santamu.
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' reinvention into its now-iconic Metroidvania formula), 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 hurt 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 Castlevania: Aria of Sorrow and Castlevania: Dawn of Sorrow, which are a few decades in the future rather than the typical late medieval setting, as Genya Arikado).
Several City-States eventually joined the game as full Civilizations. These include: Jakarta (Indonesia)note Khmer and Indonesia DLC, Amsterdam (The Netherlands), Seoul (Korea)note Rise & Fall expansion, Carthage (Phoenicia), Toronto (Canada)note Gathering Storm expansion, Palenque (Maya)note Maya & Gran Colombia DLC, Antioch (Byzantium)note Byzantium & Gaul DLC, Babylonnote Babylon DLC, and Lisbon (Portugal) note Portugal DLC.
Uniquely, Simón Bolívar was originally a Great General before he ascended to become the leader of Gran Colombia in the ''Maya & Gran Colombia DLC.
It should be noted in all cases, every single Ascended Extra noted are still extras if you don't have the required DLC.
Conqueror's Blade: PvE modes used to feature bands of raiders composed of units that players could normally control...plus a few bonus units that weren't in any tech tree or season. Then, in Season XVI: Sengoku, some of these formerly NPC-only troops were released as proper units (Ronin, Naginata Monks, and Matchlock Ashigaru) for players to unlock and use.
In Crusader Kings II, there's a small chance that one of the nameless soldiers will distinguish himself in combat, which turns him into a proper, named character who joins the player's court and is then treated like any other named character (can hold titles, can participate in factions and be their target, can command armies, and so on).
The Legendary Chalice from Cuphead was a minor character who showed up a few times throughout the game in mausoleums where she gives you super abilities. However, in the DLC "The Delicious Last Course", she takes on the form of Ms. Chalice, a third playable character and becomes a major character ever since.
Magisa, a recurring character in some of the games made by Cygames. In Rage of Bahamut, she originally appeared on some cards as "Witchcrafter" without a name. Her status as an ascended extra started in Granblue Fantasy where she's a fully fleshed out character. She later appeared as a card in Shadowverse.
Sergeant Merrick has a minor NPC speaking role in the original campaign of Dawn of War II. For the Imperial Guard campaign of Dawn of War II: Retribution, he is finally, and thankfully, playable.
Techmarine Martellus goes from the Mission Control in the original game, to a playable character in the Space Marine campaign.
Several of the survivors of the Eldar warhost play roles in Retribution as well. Ronahn and Veldoran are playable in the Eldar campaign, and both were present in the original game, during the Eldar attack on Angel Forgenote Ronahn was the sniper who shouted "Nemerian was the best of us, humans", and takes potshots at your squad from a watchtower, and Veldoran was likely Idranel's second in command Warlock. The female Howling Banshee Exarch who attacks you at Angel Forge is also present as a minor antagonist for one of the optional missions in Retribution.
In Dayshift at Freddy's, Phone Guy is one of the main characters whereas in his origin game he was a relatively minor character.
In the original Dead Space, Brant Harris, Doctor Elizabeth Cross, acting Engineer chief Jacob Temple and Chen were all just minor characters in the game with Chen being the first person killed by the Necromorphs, Brant only having his name brought up once in a Log and Cross and Temple both killed with Temple being killed by Challus Mercer in front of Isaac. In the Dead Space (Remake) however, all of their roles get expanded significantly. Chen ends up coming back as a Necromorph and takes the place of the random slasher from the original that Hammond sent out in an escape pod and killed the crew of the USM Valor as well as taking the place of the Brute that killed Hammond by having them both die after being pulled into the engine of the ship. Brant Harris is revealed to be a Unitologist and willingly allows Mercer to inject his skull with Necromorph tissue and becomes the Hunter Necromorph that chases you throughout the game while still aware of his life as a human instead of the random victim Mercer used in the original. Isaac also meets both Elizabeth Cross and Jacob Temple earlier and helps them out with certain tasks before they end up dead with Temple getting shot in the head by Mercer and Cross getting killed by Kendra Daniels after revealing to Isaac that she was the person that Isaac saw as Nicole due to Marker Dementia.
Daud is the assassin who murdered the Empress Jesamine Kaldwin. He appears at the beginning of the game to do the killing, and again near the end to confront Corvo after the Loyalists betray him and dump him in the river near Daud's hideout. The game's two story DLCs - "The Knife of Dunwall" and "The Brigmore Witches" focus entirely on him (Corvo doesn't appear outside of a dream until the very last seconds of "The Brigmore Witches") and what he was doing while Corvo was exacting his revenge. Also doubles as Hero of Another Story.
Princess Emily herself goes from a Living MacGuffin in Dishonored to one of two playable characters in Dishonored 2.
Charon the Ferryman didn't have any dialogue in the Hercules movie, but has dialogue in the Disney's Hades Challenge video game and is a major part of a puzzle to sort incoming souls.
Isabela in Dragon Age II. In Dragon Age: Origins, she was a character who taught a Rogue specialization. She becomes a party member and a love interest in the sequel, and even returns in Dragon Age: Inquisition as a DLC playable character in the multiplayer mode.
Merril in Dragon Age II. In Dragon Age: Origins, she was a Guest-Star Party Member for the Dalish Warden's prologue. Like Isabela, she becomes a love interest and party member in the sequel.
Also Anders to a lesser degree, he was a party member in Dragon Age: Origins – Awakening as well, but his role was greatly expanded on and his character was fleshed out much more in Dragon Age II.
The entire Qunari race. We saw two or three in Origins and heard a little about their culture, in Dragon Age II the plot of a third of the game centers around them. Dragon Age: Inquisition takes it even further, as they join the humans, dwarves and elves as a playable race.
Cullen. In Dragon Age: Origins, he's a minor character whose only role is to have a dorky crush on the mage PC and get traumatized by demons to show how idealistic Templars can turn into anti-mage hardliners. In Dragon Age II, he returns as Meredith's lieutenant, and gets some character development when he finally realizes it's the Templars who are going off the deep end (or at least, allowing Meredith to lead them there). In Inquisition, he's in command of the Inquisition's military forces and acts as an advisor (and if you end up facing Samson, a Guest-Star Party Member), and is Promoted to Love Interest.
The (formerly) nameless Avvar Sky Watcher encountered during a side-quest in Dragon Age: Inquisition became a playable Agent in the Dragonslayer multiplayer DLC.
Samson was a washed-out ex-Templar and lyrium addict in Dragon Age II, who showed up briefly in two sidequests. In Inquisition he's The Dragon to the game's Big Bad if the Herald sides with the mages.
Dragon Quest III: The female Warrior and male Fighter have made cameo appearances in some of the other games in the series as Dragon Quest VII.
Dragon Quest IX: Patty and her bar have been a Recurring Element of Dragon Quest since DQIII, as a matter of fact, managing party members in III, Dragon Quest V, and Dragon Quest VI (where she also manages monster buddies). IX, however, brought her into the limelight, bestowing a unique design and personality upon her, no doubt in order to highlight the Party Planner in the franchise's first major multiplayer game.
Mike from Drawn to Life is a minor NPC in the original game, but in the DS version of the sequel, it's revealed that the events of the game have been taking place in his head as the result of a car crash-induced coma.
Mirei Ozawa was originally only mentioned in the Character Bio of her sister Kanae in Dual Blades and is now a full-fledged playable character in the sequel Slashers: The Power Battle as a Ninja with a reworked backstory.
This happens quite often in the Dynasty Warriors franchise, given the historical nature of the setting and the numerous installments that build on the previous ones. All characters in the series are largely based on history, so even the generic Non Player Characters are based on real people. Oftentimes, the more prominent NPCs in one installment could very well end up becoming a fully-fledged playable characters in a future installment, as proven time and time again. They usually get a design overhaul too.
You probably wouldn't expect Cao Cao's son Cao Pi to be an example of this, but here's how his story goes: In the third Dynasty Warriors game, it was his first wife Zhenji that debuted, and from there and the fourth game, she became Wei's Smurfette Breakout character, while Cao Pi is stuck in the shadow of his much more famous father and his much more sympathetic first wife. Come the fifth game, Koei decided to put Cao Pi as a playable character... and then he became some sort of pseudo-Breakout Character, usually being crowned the most popular Wei character, eclipsing both Cao Cao and Zhenji in popularity thanks to some Historical Hero Upgrade and his personality being rounded more; he tends to get heavily featured in the Warriors Orochi subseries as a result (and gets a deification form in the 4th game!). Not bad, for someone who's almost doomed to be the disposable Domestic Abuser...
Back in the first Samurai Warriors, a generic officer named Honda Tadakatsu stood up in defense of Tokugawa Ieyasu during the battle of Mikatagahara, and Takeda Shingen refers the him as one of Ieyasu's luxuries. When the first Xtreme Legends game added four new playable characters, two of them were Toyotomi Hideyoshi and Imagawa Yoshimoto, who received unique character models despite only being NPCs in the vanilla version, one of them is a brand new archer called Inahime, whose father is... Honda Tadakatsu, who is the last playable character and ascended so quickly he practically became SW's answer to Lu Bu.
In Hyrule Warriors, many of the minor characters that have appeared throughout the Zelda franchise make their appearance in this game's roster as playable Warriors. In fact, this was one of the major selling points of the game, in which Zelda fans can finally kick some ass as someone who isn't Link.
One Piece: Pirate Warriors has 4 installments, each of which builds upon the roster of the one before it. Many of the new additions in each installment were characters that have already appeared in previous games as Non Player Characters, before becoming fully playable.
Arslan: The Warriors of Legend also features some playable characters that players may not have even remembered from the TV anime, due to how minor of a role they served.
Peter Puppy of Earthworm Jim served as a minor assistant (or hindrance) in the original games. In the animated series he is promoted to Jim's Kid Sidekick and Heterosexual Life-Partner. Earthworm Jim 3D uses concepts and character traits from the show, and thus Peter has a similar expanded role, acting as a tutorial character.
In Morrowind, Jiub is the Nerevarine's shirtless, bald, one-eyed fellow prisoner aboard the Imperial Prison Ship at the start of the game. He lets the Nerevarine known they've arrived in Morrowind and asks for the Nerevarine's name, and is never seen again once the Nerevarine exits the ship. Despite his very limited role, he was popular enough with fans to generate countless Fan Fics and Game Mods which add him back into the game. Bethesda took notice and, in Oblivion, mention that became a Saint in Morrowind for driving the (much reviled) Cliff Racers to extinction. His spirit makes a cameo in Skyrim's Dawnguard DLC, where he offers a sidequest in the Soul Cairn.
The Daedric Princes have been around since Daggerfall, offering special sidequests and granting legendary artifacts as rewards for completing them. A few, like Azura and Mehrunes Dagon, have been involved in the main quests of the games that followed. However, some have also gotten A Day in the Limelight "episodes", especially during the expansions and DLCs of the games that followed. To note:
Hermaeus Mora, the Daedric Prince of Knowledge and Keeper of Forbidden Knowledge, plays a large part in Skyrim's Dragonborn DLC. The Big Bad is his former 'champion' turned Starscream, while he would like to bring the player character aboard as his new champion...willingly or otherwise.
The Sheredyn faction of Endless Space, the personal bodyguard fleet of the United Empire's emperor, was originally a collector's edition exclusive race, that was a carbon copy of the United Empire with a slightly different aesthetic. Come the release of the DisharmonyExpansion Pack, the Sheredyn are included into the base game as a major faction, and while they still share United Empire traits, they now have a unique ability and traits based on honor.
Fallout 3 has Mayor R.J. MacCready, a foul-mouthed Bratty Half-Pint who must be persuaded to let you into Little Lamplight so you can progress through the game's main story line. Fallout 4, which takes place a decade later, finds the now adult MacCready as a mercenary sniper in the Commonwealth with Gosh Dang It to Heck! tendencies. He is one of the companions available in game and will accompany you around for a small fee. If he likes you enough, MacCready also offers a quest to follow, in which you find out more about his past, including that he's a widower with an ailing son he was forced to leave back in the Capital Wasteland.
In the remake of Final Fantasy II, Prince Scott of Kashuan, who dies less than an hour into the game, is one of the members of the "Soul of Rebirth" bonus scenario.
Final Fantasy IV: The After Yearsloved this trope — numerous party members were minor characters in the original game, and one such party member was so minor as to be an NPC that only appeared in the ending. Meanwhile, The Dragon ascended from being a one-of enemy in a short sidequest exclusive to the original game's Gameboy Advance release.
In the original version of Final Fantasy V, Enuo was mentioned once as being the one indirectly responsible for the plot and never showed up at all. In later versions, he was made into the game's ultimate opponent.
Tseng of Final Fantasy VII. In the original game, he is the leader of the Turks, but you never fought him, and he only appears for a short while. Come Crisis Core, he becomes Zack's Turk partner, and could fight alongside him in a DMW sequence. And Vincent Valentine in the original game was just an optional party member. In Advent Children, he's one of the main characters along with Cloud and Tifa, and he later got his own spin-off game in Dirge of Cerberus.
Final Fantasy XI: A huge amount of the time in The Voracious Resurgence is spent spending time with a lot of minor characters and side characters from throughout the game. Uran-Mafran goes from a villain in a side quest to one of the central characters in its plot and Zhuu Buxu and Incantrix were a random NM and a battle system NPC respectively but both are given their own arcs as well.
Players first learned of eccentric Gentleman Inspector Hildebrand Manderville's father Godbert Manderville through text in the Hildebrand missions in 1.0. He finally shows up in 2.2's Hildebrand mission but tends to stay here despite being mentioned as one of the heads of Ul'dah's ruling Syndicate, leaving that role to scheming Lalafells like Lolorito. He makes his presence known in the main story, to the surprise of many, in Patch 4.1, when Sultana Nanamo ul Namo seeks him out and he helps her with a solution on how to get the liberated Ala Mhigo back on its feet.
Omega is a recurring Bonus Boss in the series. In the Stormblood expansion, it is the chief antagonist of its own raid questline, and is revealed to not be the product of the setting's resident Precursors, but an alien war machine responsible for destroying the dragons' homeworld, as well as capable of Reality Warping as a means of making itself more deadly.
Final Fantasy XV plays with this in the form of Ardyn. When the character was originally given a concept in 2010, he was merely The Dragon to then Versus XIIIBig Bad Aldercapt. Over the course of the change from Versus XIII to XV, Ardyn was promoted into the big bad.
Biggs, Wedge, and Jessie were relatively minor characters in the original game, but throughout the first several chapters get a significant amount of development. Jessie, in particular, gets a section where her parents are shown, and her dreams of being an actress are introduced.
The Hell House, Eligor, Brain Pod, and Sword Dance were basic random encounter mooks in the original game. In Remake, all four are boss battles.
Pradda Nsu-Yeul was briefly mentioned in the datalogs in Final Fantasy XIII, but became a plot-critical character in Final Fantasy XIII-2. Nevermind Serah being elevated to a main character in said game.
The crossover game Dissidia Final Fantasy ascends several characters from several different games. The Cloud of Darkness is upgraded from a Giant Space Flea from Nowhere with no personality to a thoughtful individual whose true desire is to keep the balance between the light and dark. The originally Flat CharacterShinryu got to be a major player in the game's backstory. And Cid of the Lufaine from the first Final Fantasy game (who was introduced into the game retroactively) became the instigator of the game's central plot.
Finding Light: Downplayed with Tiamat, who was a Superboss with no lore in the previous game. In this game, she's another of Zamas's pawns and a mandatory story boss, having been driven to insanity.
Leif, the prince of the fallen Leonster, was just another second-generation child unit in Fire Emblem: Genealogy of the Holy War, albeit one with a familial relation to the main protagonist Seliph. The next game, Fire Emblem: Thracia 776, would see Leif becoming the protagonist, and a Hero of Another Story as he fights to wrest control of Leonster from Travant, king of Thracia.
A few characters who were only mentioned in support conversations in Fire Emblem: The Binding Blade, like Canas, Pent and Louise, went on to become playable characters in the prequel Fire Emblem: The Blazing Blade. Hector and Eliwood count as well: Eliwood was never seen again after his son Roy set off on his journey, and Hector dies very early on in Binding Blade. Both became protagonists of the prequel.
Sothe the thief from Fire Emblem: Path of Radiance and Fire Emblem: Radiant Dawn. From just another playable character (who couldn't even promote) in Path of Radiance to an important supporting character in Radiant Dawn.
The Fire Emblem Fates second generation characters were given the Demoted to Extra treatment in-story, but the Heirs of Fates DLC stages make them the protagonists.
Monica, Rodrigue, and Holst are all Promoted to Playable and take on major supporting roles in their respective factions' armies.
Duke Aegir, the Evil Chancellor who was the ringleader of a coup that all but destroyed the Adrestian Empire's ruling family, is only seen in a few optional cutscenes in Three Houses, but is promoted to an active antagonist in Three Hopes' Scarlet Blaze and Azure Gleam stories.
Randolph, an Imperial general who is killed by Church of Seiros-aligned forces in every route in Three Houses, is given a much larger supporting role in Three Hopes, appearing at the start of the campaign of the Scarlet Blaze route (where it's possible for him to survive to the very end), a temporary ally in Golden Wildfire (where he doesn't), and as an Anti-Villain boss in Azure Gleam. His younger sister Fleche also becomes this to a lesser extent, becoming an Adaptational Badass in the process as an active combatant.
In the original Five Nights at Freddy's, the Golden Freddy was an Easter Egg, and it was possible to finish the game without even seeing it. In the sequel, however, that's not the case; Golden Freddy is likely the most difficult enemy in the game.
Frogger: The Great Quest introduces a minor villain named Mr. D who appears in a one-off boss fight that ultimately has no impact on the game's story. In the game's semi-spinoff Frogger's Adventures: Temple of the Frog, Mr. D returns as the main antagonist and final boss.
The Grand Theft Auto series is a prime example, as in most of the spin offs protagonists are minor characters in the main titles.
Guilty Gear: Axl Low initially started off as a fairly minor character pining for his lost timeline and lover Megumi who was rather insignificant in the grand scheme of things. Come Xrd however, he and his unstable ability to Time Travel become much more crucial to the plot, with -STRIVE- revealing that Megumi's alternate self eventually became I-No — giving Axl a personal stake in the main story.
Half-Life has about three "skins" for all of the scientist models, all of whom exist solely to provide exposition, open certain doors and/or die horribly and thereby show the player how not to die horribly. Two of these skins were later used as the basis for two of the main characters of Half-Life 2, which has led to interesting arguments about which of the scientists is the "real" one (Eli is explicitly stated to be the first one to talk to Gordon and ask him to get topside to call for help after the Resonance Cascade; Kliener is generally considered to be the only scientist seen wielding a weapon, appearing at the end of the "Lambda Core" level, due to a sequence with him at the end of "Entanglement" in the second game which pays homage to that scene). Barney, a character similarly based on model skins, this time of the security guards (of which there was only one originally) is more of a Mauve Shirt however.
In the firstHalo game, Sergeant Johnson was just a Played for Laughs NPC who happened to be handy with a sniper rifle. He becomes a major supporting character in the rest of the main trilogy, and was one of the protagonists in the novel Halo: Contact Harvest. In part to reflect his growing importance, Bungie went so far as to reveal that he was actually a Spartan-I.
The Harvest Moon series has quite a few instances of this.
Rick in Harvest Moon 64 was just another shopkeeper. In the PS1Harvest Moon: Back to Nature titles, however, he was promoted to being a rival slash Love Interest and has retained this position for the rest of the series and subsequent appearances since.
In another branch of the series, you have Alisa, novice priestess to the Harvest Goddess. In her first appearance in Island of Happiness, she was merely the cute assistant to Good Shepherd Nathan. In Sunshine Island, she was one of your potential love interestsnote Though that turned out to be a cruel fake-out on the Dev Team's part. In The Tale of Two Towns, she is one of two unlockable female love interestsnote with yet again another catch — you can't have a child with her..
As DS uses the same cast set years apart, this also ascendes Griffen, Carter, and Flora into marriage candidates.
The Switch remake of A Wonderful Life has Gordy (formerly Cody) be promoted as a new marraige candidate after being a NPC throughout his previous appearances.
Woofio first appears as the animal contest judge in Story of Seasons (2014), meaning he wasn't even interactable as an NPC. He later appears again in Story of Seasons: Trio of Towns, but now as a fully interactable NPC and marriage candidate.
Dr. Boom is a name that's feared in Hearthstone, but virtually unheard of in World of Warcraft. Dr. Boom has his humble beginnings as an unimportant quest boss from the Burning Crusade expansion, but all that would change with the release of Hearthstone's first expansion, Goblins vs. Gnomes, where he absolutely terrorized the meta as a War Golem that with a Battlecry that summoned 2 explosive Boom Bots. To give you an idea of how much of a Game-Breaker he was, at the peak of his reign, he was in virtually every deck that didn't aim to win before reaching 7 mana and because his only decent counter, Big Game Hunter, was ran just as often as he was, every other big minion with 7+ Attack was useless if they didn't also do something insane on the turn you summoned them. His infamy eventually lead to him becoming the star of his own expansion, The Boomsday Project, 3 years later, and a year after that he became part of a Legion of Doom with other Hearthstone villains.
From that same Legion of Doom, Madame Lazul was originally the unnamed female troll narrating the Whispers of the Old Gods trailer. She became part of the villain team, with some hints that she's actually a Faceless One dropped on her.
Captain Eudora is also one-third of a minor boss battle in WoW and (apparently) dies, but becomes a fully playable hero in Hearthstone. She simply proved popular with fans, being a cute VulperaPirate Girl.
The Edutainment series Jump Start: Frankie the dog was always a relatively important character, but in the 2001-2004 incarnation of the series, he became the central character as well as the entire series' mascot.
Kingdom of Loathing did this with Ed the Undying, combining the trope with Breakout Villain. He was originally a semi-important boss several steps removed from the Big Bad, with his only gimmick being that you have to "kill" him several times (he's a very persistent mummy). But he was popular enough to get his own "Challenge Path" where you play through the whole game from his perspective, defeating your normal human character at the end instead of the usual final boss.
Before the final boss of The King of Fighters '94, a blonde woman escorts your team to Rugal's chamber. After a number of victories in KOF '95, a brunette woman informs the unseen Rugal of your team's progress. These two otherwise unremarkable secretaries would go on to become playable characters in KOF '96 under the names Mature and Vice, complete with relevance to the Orochi storyline. And even though they were both killed at the end of the game, they still proved popular enough to return in full-cast compilation games, future installments such as KOF XIII and KOF XIV and intercompany crossovers. Who could have known that a pair of background characters would become Iori's most consistent teammates?
The excellent Fan Remake of King's Quest II does this with several Non Player Characters. Perhaps the best is Valanice, who was rewritten from her original flat, MacGuffin-esque Damsel in Distress portrayal to a character more in line with what's seen in her later appearances in the series, who — although a prisoner — is hardly a helpless shrinking violet. Similarly, the vampire (originally Dracula; Caldaur in the remake) is turned into a sympathic character with personality, depth and motives, who will end up aiding the hero if you help him in return. Seeing as his original role was to hang out in his castle until the hero showed up to kill him for no apparent reason (other than needing the key he had), this was a definite improvement. And in the original versions of the series, Rosella was given her own adventure to star in after appearing briefly in the previous game as the Damsel in Distress, and later on she co-starred alongside Valanice as the heroes of King's Quest VII. Princess Cassima, meanwhile, was introduced near the end of King's Quest V and was later ascended to being a major character in King's Quest VI.
Adeleine in the Kirby games, as she was confirmed to be the same character as Ado in a 2017 artbook. She was introduced in Kirby's Dream Land 3 as a simple boss character, but she then became one of the main characters in Kirby 64: The Crystal Shards and, as of July 2018, a Dream Friend in Kirby Star Allies.
Gooey from Kirby's Dream Land 2 was originally a simple health restoring item that sometimes showed up instead of an animal friend, but in Kirby's Dream Land 3 he was promoted to Kirby's partner in co-op mode (or an optional computer-controlled ally in single-player). Like Adeleine he became a Dream Friend in Kirby Star Allies in a post-launch update.
Knight Bewitched 2: The Deepforge dwarves were sidequest characters in the previous game. In this game, they're more involved in the main plot because the party is helping them reclaim their home in the Underworld.
The Happy Mask Salesman was only part of a minor subquest in Ocarina of Time. He became an unlikely major character in Majora's Mask.
Also from Ocarina of Time, the nameless Cucco lady in Kakariko Village is only briefly relevant in a minor sidequest to get a bottle and as the starting point of the Biggoron's Sword quest. Compare to her Termina counterpart Anju from Majora's Mask, who doesn't just get a name but is one of the two central focuses of the longest, most involved side story in the game that must be done at least twice to get everything from it.
As far as gameplay goes, collecting masks was just a minor sidequest in Ocarina of Time. In Majora's Mask, they are one of the main gameplay features.
In The Legend of Zelda: Twilight Princess, Agitha appears in the Castle Town as a somewhat crazy bug enthusiast and gives you the game's "collect things to make large amounts of Rupees" sidequest. Come Hyrule Warriors, she's a plot-important NPC during the Twilight Princess arc and is one of the game's unlockable fighters.
Impa appears in the manuals of the first two games as the old advisor who sends Link on his quest, but has no named in-game presence. In Ocarina of Time, her identity as a Sheikah, Zelda's guardian and eventually one of the Sages is revealed. In The Legend of Zelda: Skyward Sword, her guardian role is expanded into becoming a foil for Link, and she has far more relevance to the plot than first apparent. And then she is the second playable character obtained in Hyrule Warriors.
The Sheikah race as a whole were notably obscure despite being around since their debut as a race in Ocarina of Time. Impa (or Impaz) was the only Sheikah that appeared in many games, and was often stated to be the last of her kind. In The Legend of Zelda: Breath of the Wild, not only does the lore of the Sheikah expand greatly, but the rest of the Sheikah tribe finally appear for the first time ever, with Impa herself being portrayed as having a sister and a granddaughter. They even got an Evil Counterpart in the form of the Yiga Clan.
The Legends port of Hyrule Warriors has King Daphnes Nohansen Hyrule. Formerly the ruler of the sunken land of Hyrule in the Era of the Great Sea, now he utilizes his alternate form, the King of Red Lions, and said form's mast and sail in battle.
Hyrule Warriors: Age of Calamity continues its predecessor's trend of Promoted to Playable while also giving expanded roles to formerly minor characters. In addition to the aforementioned Impa, Purah and Robbie serve as the central supporting cast of the plot even before becoming the focus of the DLC expansion packs. Master Kohga goes from a one-arc comedic boss fight to a recurring antagonist with his own Dragon. The most dramatic upgrade goes to Hestu, who becomes one of your playable fighters even before the Calamity strikes, which is a significant upgrade from his former role as an inventory upgrade merchant.
Tulin was mostly a Satellite Character to Teba in the previous game, with his only focus being a brief sidequest where Link helps him practice his archery. In the sequel, Tulin is the primary supporting character of the whole Rito Village questline, and at the end of it, he becomes the Sage of Wind.
The Zonai were a race whose architecture could be seen across Hyrule in Breath of the Wild, but for whatever reason they weren't around anymore, leaving fans little to go off of in terms of what they were like. In Tears of the Kingdom, not only has the Ancient Shiekah's Lost Technology from BOTW all been replaced with Zonai tech, a major supporting character in Rauru is a Zonai.
Sophie of Hateno Village. In Breath of the Wild, she was merely the Shrinking Violet purveyor of Ventest Clothing. In Tears of the Kingdom, her much more flamboyant sister Cece decides to run for mayor of Hateno Village against current mayor Reede and ropes Sophie into organizing the election, forcing her into a prominent role as part of a multi-quest story arc.
Pocket Circuit Fighter from Yakuza 0, one of the characters from a mini-game, re-appears in Kiwami alongside said minigame. However in 6 he only appears as part of a sidequest, and in Yakuza: Like a Dragon, he returns alongside a different minigame.
Onomichio from Yakuza 6, even though he is the mascot of a city that appears in a single game, he appears as a DLC character for the Clan Creator minigame in Kiwami 2, there are also female versions of him as hostesses that appear as pre-order bonuses in the Cabaret GP minigame. He later appears in a substory in Judgment where the costume is used to commit a robbery. In Yakuza: Like a Dragon, Onomichi appears as summoned Poundmate, as well as a bootleg version of him being part of a side-story.
In the original Little Busters! game, Sasami and Kanata exist primarily as Satellite Characters to Rin and Haruka respectively. In Ecstasy and the later sequels, they're fully-fledged love interests with routes of their own.
The hero's main Love Interest Luna from Lunar: The Silver Star. In the original game for the Sega CD, she fought with the protagonist as the White Magician Girl (with a Magic Music power) for the first dungeon and returns home, not appearing again until the Big Bad kidnaps her and it's revealed that she is a routine human incarnation of the world's goddess and has to be saved. In the game's subsqent remakes, starting with the one on the Sega Saturn, she stays with the group until the mentioned kidnapping, but it doesn't wholly matter because the player gets three farmoreuseful spell casters along the way, and the main character can also obtain powerful magic later in the game.
The men who killed Tommy Angelo in Mafia: The City of Lost Heaven appear in Mafia II as its protagonist, Vito Scaletta, and his best friend, Joe Barbaro. One level even features them killing Tommy as a mission.
While he may seem like one of many other characters the player can pick to go with them in Maniac Mansion, Bernard arguably fits this trope, becoming the hero of Day of the Tentacle, which suggests that the canonical trio includes him.
Mass Effect 2's EDI was never precisely an extra, being your ever-present Spaceship GirlVoice with an Internet Connection, but nonetheless receives a major step up in Mass Effect 3 when she hijacks a Cerberus robot body and becomes a full squadmate. An optional scene near the end of 3 takes this even further by revealing that EDI was the rogue VI in Luna in the first game, or at least she was built from it.
Cerberus itself, who go from sidequest baddies to major players in 2 and 3.
Admiral Hackett went from being a Voice with an Internet Connection who calls in to deliver sidequests in 1, to appearing in a single DLC in 2, to becoming arguably Shepard's most consistent and trusted contact for the entire Reaper War in 3.
While they were squadmates in the first game, Garrus and Tali had a noticeable lack of focus on them compared to some other squadmates. Come the second game, on account of their popularity they were Promoted to Love Interest (with the actual Love Interests from the previous game being demoted) with much more influence on the plot. It's also notable that they are the only two characters in the series who can be squadmates for the entire trilogy without DLC (joined by Liara, who becomes a temporary one during Lair of the Shadow Broker).
While not as much of an extra as most, Joker was essentially just a part of the scenery for most of 1. In 2, he gets way more fleshed out as a character and is established as one of Shepard's most loyal followers.
Dr. Chloe Michel starts off as a bit character who gives you a lead on the Starter Villain and one sidequest in 1 and sends you one e-mail about how she's doing in 2. In 3, she can be recruited to the Normandy SR-2 to replace Dr. Chakwas as the chief medical officer and accompany you throughout your adventures.
In 2 and 3, the krogan clan Nakmor are background characters, with Shepard only meeting their representative if Wrex survived Virmire. In Andromeda, they're the leading clan of the Initiative, instead of Clan Urdnot, who got the lion's share of the focus in the original trilogy.
In The Matrix: Path of Neo Switch and Apoc are given slightly bigger roles from their original status as Red Shirts in The Matrix in that they speak more than a few sentences. Along with offering and being help against the SWAT teams in the sewers. Plus, in an earlier level, Apoc, without Switch, helps Neo fend off some SWAT and find the group.
In the first Mega Man Star Force, Damion Wolfe and his FM-ian, Wolf, are just Optional Bosses you can challenge anytime you want. In the third game they were promoted to secondary characters, helping our heroes in an occasion or two. In the anime he was also promoted, but to a "villain" (well, he softens up later).
Mega Man Battle Network has Tory Froid, who is nothing more than a generic, nameless NPC but was upgraded to one of Lan's friends for MegaMan NT Warrior and given a unique design. IceMan is his Navi in the anime but is his father's Navi in the game.
Bass in the first Battle Network was just an Optional Boss, but became one of the villains in the two next sequels. Battle Network 4 and beyond then turned him into an extra again, but at least he gets dialogue. He was important in the anime and manga adaptations, too.
Players who have seen Mega Man 8's cutscenes might recall that Evil Energy was part of the game plot, and its intro had Duo and an unnamed robot, whom we'll call the Evil Energy robot, fighting before both of them defeat themselves and collapse into the atmosphere of Earth. Mega Man 8-Bit Deathmatch does exactly this, and guess who's the Final Boss (or rather Disk-One Final Boss) for chapter 8? Why, it's the Evil Energy robot, instead getting his own day in the limelight by appearing out of nowhere in one of the matches, absorbing the powers of the 8 robot masters, and flying out to space; Duo, who's in pretty bad shape and cannot fight it himself, lends his fist to the player to stop them for good. Unfortunately, this isn't the end of the Evil Energy nor the Evil Energy robot, though, seeing as the former gets refined into the Roboenza virus by Wily in V5's ending and the latter is revealed to have to barely survived, hijacking Sunstar and the Wily Star in V6, turning it into the Mechanical Abomination known as Eclipse.
Mega Man's supports that aren't Rush play a greater role in Rockman 7 EP compared to Mega Man 7. In Wily 5, they fight alongside Mega Man through the Multi-Mook Melee and help open the way forward.
An example that is Zigzagged between this and Demoted to Extra in Rockman 7 EP: Bass has always been fought as a midboss, never as the actual boss of any given stage; here though, he's the post-final boss and among the hardest fights in the game. However, his recurring presence throughout all of Mega Man 7 is removed in favor of that singular appearance at the end.
Iris' death in Mega Man X4 is one of the most iconic moments in the series, and the developers ended up feeling so bad for her that they made Mega Man Xtreme 2 a prequel to X4 so that she could show up one more time. Mega Man X5 shows that Zero is still haunted by her death, and she's since gotten special artwork made for her for the Mega Man X Legacy Collection and even made a cameo in Project × Zone, as well as becoming a major character in the Alternate ContinuityMega Man Battle Network series though she ultimately suffers the same fate there as well.
Johnny Sasaki from the Metal Gear franchise. In Metal Gear Solid he's a purely comedic side-character with bowel issues, which remains in place for his brief camo in Metal Gear Solid 2 and his grandfather's appearance in Metal Gear Solid 3. In Metal Gear Solid 4 he's still a purely comedic side-character with bowel issues until around Act 3, from which point he quickly evolves into Meryl's love interest and a Badass Normal on par with her.
This is the endgame twist in Metal Gear Solid V: The Phantom Pain. The Player Character is not the Big Boss you've been playing as since Metal Gear Solid 3, but a Body Double who made his debut as a nondescript male MSF soldier in Peace Walker. He went on to become the medic in Ground Zeroes who performed surgery on Paz, and nine years later, he's building on Big Boss's legacy and avenging those who wronged him, while Big Boss himself builds the nation of Outer Heaven off-screen.
Metroid: Ridley started out as just one of three bosses in Metroid, given very little fanfare. Super Metroid was the first game to give Ridley more prominence, by making him the one who stole the Metroid Hatchling and its guardian in Norfair. Now, he holds the status as Samus' most hated enemy, a recurring character in almost every game, and one of the most beloved (and difficult) bosses in each of his appearances.
Ratbag the Coward from Middle-earth: Shadow of Mordor was simply one of the possible generated orcs from the Nemesis system from the demos, but, in the game proper, he's been promoted to an actual story character, the first orc you have at your command. The devs had apparently loved his personality too much to leave him dead from a failed assassination attempt on his master.
Minecraft: Story Mode: Aiden and the Ocelots (later called The Blaze Rods) go from mildly annoying bullies to the Big Bads of Episode 5.
Mr. Saitou: In the previous game, the Llamaworms were all shy NPCs named "Saitou-san" who only appeared in the tunnels underneath the forest. This game features a whole corporation full of Llamaworms, one of which is the protagonist himself.
Mortal Kombat: Special Forces is generally regarded to be the bottom of the barrel of the series, but fans latched on to one of the bosses in it: Tremor. Fans had demanded since his appearance to come back. In the PS Vita version of Mortal Kombat 9 he appears as a bonus boss. After 15 years of fan demand, Tremor finally makes his debut as a playable character in Downloadable Content for Mortal Kombat X.
In Mutant League Football, all players have the same portrait and quotes depending on their species. When Mutant League Hockey rolled around, several of the best players from MLF gained unique portraits and quotes, including Bones Jackson, KT Slayer, and GIL-9000. They're even mentioned by name in the opening credits ("Mutant League Hockey, featuring..."). See also the cartoon, where most of the mentioned players were main or recurring characters. Also on the show was the Razor Kid, who while a standout on the Screaming Evils in Mutant League Football wasn't in Mutant League Hockey and thus didn't get the "star" label like the others.
Esther from Mr. Hopp's Playhouse is initially The Ghost in the first game, where even her physical appearance was a trap used by Mr. Hopp to lure Ruby. However, her role is greatly expanded as the main protagonist, with the second game shows her backstory on how Esther received and dealt with Mr. Hopp in the first place along with being an overarching character to the series' storyline as a whole.
Deekin ascended to party member near the end of Neverwinter Nights: Shadows of Undrentide, and played a significant part in Hordes of the Underdark as well.
Rilo Dopplelori from Noitu Love started out as nothing more than an evil robotic duplicate of the game's Mission Control character, who appeared just in time to be the stage boss of Level 5 and disappear right after. In the sequel, she's now the second playable character of the game (while the character she's built to imitate is long dead,) with her trying to get to the bottom of who reactivated her and the rest of the Darn Army and eventually destroying their hidden base and deciding to rebuild the Darn Army under her control.
Oedipus in my Inventory stars an unnamed shepherd who only appeared in one scene of the original play. The game covers his involvement in several parts of Oedipus' history mentioned but not seen in the play itself.
Doomfist was originally created as a throwaway name in the game's debut cinematic trailer. But due to overwhelming fan request, he (or they) eventually became a major figure in the overarching story (via being one of the major leaders of Talon) and was later made into a playable character.
The Queen of Junkertown was a largely-unseen background character who only ended up getting some development following the release of the Junkertown map, with an off-screen Rousing Speech in the announcement trailer and a hidden poster in the map revealing her likeness. This sparked the playerbase's demand to see her fully realized as a playable hero, and the Junker Queen was eventually made one of the new debuting additions to Overwatch 2.
Rudy Beagle, a forklift in the Pajama Sam series, only existed in the second game to get Sam into World Wide Weather. In the spinoff game Pajama Sam's Lost & Found, he was an actual playable character, albeit getting his name changed to Mr. Forklift.
In the original game, Sunny Funny's dad, General Potter, made a single non-speaking appearance in the introduction for the final level. In the sequel, he's one of the main characters, recruiting Parappa and friends to help stop the Big Bad from turning everything into noodles.
Parappa's father was only slightly less of an extra than General Potter in the original, having a few spoken lines in the third level's introduction and appearing several times in the intro to the final one. Nevertheless, he receives much more screentime in the sequel, where he's revealed to be an Absent-Minded Professor and good friends with Sunny's dad. He also spends most of the game trying to perfect a machine that will stop the Big Bad.
Boxy Boy only appeared as an Easter Egg background character in the original. In the sequel, he's the game's tutorial character and the host of Versus Mode.
Nyarlathotep started out as merely Kandori/Guido's Persona in the first Persona, and wasn't even a final boss. Come Persona 2, it's revealed he's personally responsible for everything bad in 2 (both Innocent Sin and Eternal Punishment), and everything that happened in the first game. He's MIA during subsequent games, though many fans suspect that he's still pulling something from behind the scenes.
A variation in the Playstation Portable re-release of Persona 3: In the original and FES releases, the male protagonist had Social Links only with the female members of SEES (and Aigis wasn't even among them in the vanilla release), all of them with an inevitable romantic ending, along with a slew of classmates and other adults. The arguable biggest reason as to why the new female protagonist for the PSP release was well-recieved is that she has S. Links for the male members of SEES along with the girls, including the dog, as well as a plot-important NPC that shows up late in the game. The male protagonist could only do social interactions with the male members of SEES when walking Koromaru (again, absent in the vanilla release). The most standout example is Shinjiro, who could have his death prevented (replaced with being comatose instead) entirely if his S. Link was completed; also helped by the fact that he's only playable for one in-game month until that point.
Portal Runner: Vikki Grimm, a supporting character in the Army Men series, is the protagonist of this spinoff game.
In Princess Connect, Ayumi started out as a Recurring Extra who would appear in various cutscenes and CGs as a "mob" character. During the game's original run, she was the last playable character released before the game's termination. In Re:Dive, she once again serves as "mob filler", even showing up as early as Chapter 1 of the main story, before being made playable once more after being a main character in the Great Detective event, though she still serves her original "mob character" role. Hilariously, they justify her always being around in the background by making her a Stalker with a Crush on Yuuki.
In Project × Zone, Reiji Arisu Xiaomu, and Saya are just three characters who join the party. Its sequel, Brave New World has Reiji and Xiaomu taking up the protagonist mantle with Saya back to being the Big Bad.
In the original game, Kevin Sweeney was nothing more than a regular operative, a Recon specialist who joined up about halfway through the game. In Raven Shield he's gone on to being one of Rainbow's top advisers, giving you advice about the mission alongside the head of the entire team.
For that matter, Ding Chavez was treated the same as every other operative in the first three games — notable for a high Leadership stat and being an important character in the book, but otherwise mostly interchangeable with the other Assault specialists. Come Lockdown and he's the primary protagonist, the player character for every mission — and then in Vegas he's gone on to become the new head of Rainbow.
Red Dead Redemption II does this with Bill Williamson, Javier Esquella and Uncle from the first game, where they were primarily bit characters who mostly showed up for a few scenes here and there. In II, their their characters are considerably fleshed out and Uncle is even established as a former member of Dutch's gang.
Rebecca Chambers, an extra in the original Resident Evil, became the main character of the prequel, Resident Evil 0. Unfortunately, she suffered from Chuck Cunningham Syndrome afterwards. She did reappeared in Resident Evil 5 as bonus character in Mercenary Reunion however.
And then there's Ada Wong, whose offscreen role in the first game was simply serving as a three-letter name in a memo that provided the solution to a puzzle (a scientist's note mentions that his girlfriend's name is the password). Resident Evil 2 expanded on that bit of trivia to introduce her in Leon's storyline as an important supporting character with a Dark and Troubled Past, and then Resident Evil 4 elevated her all the way up to a full-fledged Dark Action Girl and Leon's Dating Catwoman adversary.
Resident Evil 2 (Remake) expands greatly on the roles of side characters such as Annette Birkin and Marvin Branagh. Robert Kendo is also given a bigger spotlight in a dramatic scene during Leon's campaign that sheds light on what happens to him during the Raccoon City outbreak. Kendo is also made a playable character in the non-canon side story series "The Ghost Survivors" along with Katherine Warren, whose only onscreen appearance is as a corpse in Claire's campaign.
Several minor characters that gave out side missions in Saints Row, specifically Tobias, Laura and Mr. Wong, would go on to play bigger supporting roles against some of the new gangs in Saints Row 2. Tobias and Laura (two drug sellers that would go on to get married to each other) help out against the Sons of Samedi, and Mr. Wong (a Chinese man who enlisted the Playa's services as an assassin) plays a major role late in the game against the Ronin.
In Sam And Max Hit The Road, the protagonists may optionally enter the convenience store near their office (which has no bearing on the plot or any puzzles) and save its owner, Bosco, from an armed robber. The interior of the store is never seen and Bosco is never seen nor heard. When the sequel was canceled and Telltale Games was formed as a result, due to his not-legally-a-character status, Bosco was the only character from Hit the Road (besides an appearance of the Human Enigma on a poster, due to an appearance, also on a poster, in the original Sam & Max: Freelance Police comic book series) who could legally feature in their new episodic Sam & Max: Freelance Police series. Indeed, he became a major recurring character, with appearances in all but one episode in the first two seasons and a backstory that is revealed and resolved in Season 2.
In Shining the Holy Ark, after a group of soldiers wanders into the local Haunted House and is slaughtered by its demonic master, you can talk to an otherwise generic young boy in town who says his father was one of those soldiers and listen to him swear revenge on the demon, Galm. He gets no further development in that game, but the first indication that Shining Force III is a Stealth Sequel to Holy Ark is when you realize that one of the heroes, a wandering mercenary named Julian, is that boy.
Shovel Knight has become utterly filled with examples as a result of the DLC campaigns.
In Shovel Knight's story, a bored-looking woman named Mona kills time in one of the inn's rooms in town and offers Shovel Knight a money-making minigame where he knocks flasks into targets. Come the DLC "Plague of Shadows", she's been upgraded to an experienced alchemist, the front for Plague Knight's activities in town, and most of all the motivation for his entire quest.
Percy, formerly an unnamed horseman who runs the airship's catapult in the Armor Outpost, is revealed in Plague of Shadows to be one of Plague Knight's top alchemists. As is the Magicist, the magic-upgrading woman in the village.
Specter of Torment gives significant backstory and motivations to, among others, the Troupple King Acolyte (formerly only there to sell an ichor bottle) and the guest characters Reize Seatlan and Phantom Striker (originally wandering boss encounters).
It was obvious that King of Cards was going to give greater attention to the King of Pridemoor, since their connection was established as early as the original game. Far less anticipated characters to get larger characterizations? The airship enthusiast chicken (who we learn is named Cooper) and a talking Birder NPC that was indistinguishable from the other Tower of Fate NPCs in Specter of Torment.
Shrek 2: to allow a full team of four characters at all times, several minor characters from the movie got bumped up to major playable characters:
Lil' Red goes from minor character who only appeared in one gag to a full-on main character in the game, tagging along with Shrek and co. on their adventure.
While Gingy was a recurring character in both movies, he wasn't relevant to the story until the point where the fairy-tale creatures all had to band together to break Shrek, Donkey and Puss out of prison. In the game, he takes on a much more active role as the fourth member of the group, tagging along at both Shrek's swamp and the journey to the potion factory along with his canon role in the prison break.
Fairy appears to be based on one of the fairies Shrek and Fiona trapped in a jar during the opening montage — in the game, she takes the fourth character slot in the prison level as the designated Glass Cannon.
Shrek SuperSlam: Several characters from the first two movies like Cyclops, Captain Hook, Red Riding Hood and Anthrax go from minor cameos and gags to full playable characters here.
The old arcade version of The Simpsons did a lot of this, due to only having two seasons of the show to work with. The most significant named character to be elevated as such was probably Professor Werner Von Brawn: a professional wrestler who appears briefly on TV in "Bart the Daredevil," never meets the family, and never gets a line of dialogue. He's the first-level boss.
Animated Adaptations of video game franchises seem to be fond of expanding bit players. This was especially common in earlier shows due to the usually basic (or near non-existent) storyline and character involvement in the original material, and thus writers relying on creating extra depths for what cast it has (or in some cases original additional characters):
The Sonic the Hedgehog (SatAM) animated series was intended to develop the initial games "small animal" cast —only generic animals that jumped out of badnik enemies in the game itself— into a team of heroes assisting Sonic. Alterations were made to the core cast in the final revision, however the show still used a redesigned Sally Acorn, aka. Ricky Squirrel in the east, who was arguably the most prominent protagonist other than Sonic himself.
The Adventures of Sonic the Hedgehog series expanded some of the badnik enemies from the original games and converted them into recurring henchmen for Dr Robotnik. Scratch (based largely on Clucker from Sonic 2), Grounder and Coconuts frequently appeared as comic relief in the show. This position was reversed around with the promotional Sega Genesis title Dr Robotnik's Mean Bean Machine, that not only includes said recurring characters as opponents, but uses numerous original badnik characters from the show, the large majority of them background characters from the pilot episode that weren't even given a name or speaking role in the show itself.
Soul Calibur VI: Cassandra, Sophitia's boisterous younger sister, was always just a funny side character with hardly any sway over story events. Within VI, she is only of only two people (the other being Zasalamel) who is aware of the Original Timeline, courtesy of her other self from the Astral Chaos. This makes her central to the game's Sequel Hook.
The weapon salesmen from the first Spectrobes game gets redesigned in the second with his own sprite, cutscene, and name. It's Dave, of all things.
Harmony acts as the shopkeeper of Hotlantis, a store that sells miscellaneous items to decorate your locker and splashtag. Harmony is also the vocalist for Chirpy Chips, one of the in-universe bands, and as such, her existence was relegated to promotional artwork in the firsttwo games. Her acting as a shopkeep marks the first time a non-idol band member from the Splatoon universe has appeared in-game.
Acht is the player's guide through the Side Order DLC campaign, aiding Agent 8 and Pearl in augmenting their abilities as they ascend the Spire of Order. Similarly to Harmony, she was also an in-universe musician, though promotional material for Splatoon 2: Octo Expansion only identified her by her stage name "DJ Dedf1sh".
The Big Bad of Splatterhouse, Henry West, was the one who kidnapped the protagonists girlfriend. But he never actually appeared onscreen, and was first created following the console import. When the series was rebooted, West makes his appearance and has a fleshed out story to boot.
In The Stanley Parable, Employee 432's story was an obscure and hidden gag that the majority of players missed, in that he was only given a pencil sharper and no pencils to perform his job. In Ultra Deluxe, another obscure paper reveals that a major character, the Settings Person, is in fact 432.
Similarly in Star Trek Online, numerous minor characters are revisited, most of whom were mere babies when they were shown on screen. Notable examples include Leonard James Akaar (mentioned above in Television) and Miral Paris, who was born in the last episode of Star Trek: Voyager, and Thomas Riker, Will Riker's transporter double whom the writers of Deep Space Nine cruelly abandoned in spite of fan outcry. There are villainous examples as well; Gul Dukat's half-Bajoran daughter appears, and one of the more enjoyable boss fights is against Gul Madred, the one who tortured Captain Picard.
Because of the nature of Suikoden games all being in the same world, there's usually recurring characters. A number of them are Ascended Extras, frequently as a result of She's All Grown Up. Notable examples are Apple, Futch, Luc, Sasarai, Georg, Lilly, Clive etc. Resulted in a lot of Ensemble Dark Horse.
Star Wars: The Old Republic: Darth Malora was originally a minor NPC from a side quest on Korriban, meaning only Sith Warriors and Inquisitors could encounter her, but she becomes a major player in the Jedi Under Siege update.
Star Wars: Episode III — Revenge of the Sith: One of the levels half-way through the game features an extended duel with Jedi Master Cin Dralling. In the movie, he was one of the Jedi murdered by Anakin in the video recordings viewed by Obi-Wan.
Stellaris: The nameless Captains of your fleet's ships can occasionally be promoted to the Admiralty after a battle, giving you a free fleet leader. In a similar vein, promising researchers on your science ships can occasionally give you the option between promoting them to full on Scientists or to leave them in their current position for a temporary boost to that ship's current chief scientist.
Waluigi is a mild example. Originally showing up in Mario Tennis as a fill in for Wario's partner and Luigi's rival, Waluigi's shown up in virtually every spinoff since then, and is the only regular character that hasn't ever been in a platformer to do so. He's either loved for being insane or loathed as an auxiliary character.
The starring character of Minion Quest: The Search for Bowser is a very exaggerated example. In Mario & Luigi: Superstar Saga, he was just another Goomba who you fight after a tutorial that teaches you about First Strikes, didn't speak, was not different from any other Goomba in the game, and never appeared again afterwards. In this game, he's the main character, and contributed a lot more to the plot of Superstar Saga then you may think. How does he do this, you ask? Well, let's just say... he picked up a thing or two after a little incident with a barrel. His name? Captain Goomba.
Gooigi was first introduced in the Nintendo 3DS port of the original Luigi's Mansion as the 2nd player in the co-op mode. In Luigi's Mansion 3, he's essential to progressing through the hotel, solving puzzles and defeating many of the bosses.
While many of the characters and mooks introduced in Super Mario Bros. 2 would eventually become mainstays in the series (especially Shy Guys, Bob-Ombs, and Birdo), Ninji wasn't initially one of them. After their debut, they only appeared very sporadically in minor roles throughout the 1990s (enemies unique to a single room in Bowser's Castle in Super Mario World, as minor characters in Paper Mario, etc.) and disappearing almost entirely in the 2000s. Then they returned unexpectedly in Paper Mario: Sticker Star in 2012, and from that point forward they would continue to appear routinely in the franchise, eventually returning to the mainline Super Mario Bros. series in Super Mario Run and later Super Mario Bros. Wonder. One would even be a playable character for the first time ever in Mario Golf: Super Rush
Super Robot Wars: A staple in the Super Robot Wars games is that protagonists get special pre-battle text dialogue when they attack a major boss that is not from their series or have no relevance to them in the story. The dialogue is also given to characters who were past protagonists when their sequel series appears instead where they may not be the main character. An example is in Super Robot Wars V, Kira Yamato will still get special boss dialogue text even though the official series he is from in the game is Mobile Suit Gundam Destiny where he is not the protagonist. The protagonist Shinn Asuka will still receive the special dialogue too.
Occasionally, very significant or famous characters from the series may still receive special text dialogue even if they were never a protagonist. Char's alter-ego as Quattro is treated as a protagonist in Alpha Gaiden, despite not being a protagonist or main antagonist of the series.
The most significant example is the "Shin" version of Tetsuya Tsurugi where he is little more than a cameo in the Mazinger Z reboot while he was a protagonist in Great Mazinger. In V and X, Tetsuya is treated as an equal protagonist to Koji Kabuto, despite being little more than a cameo in Shin Mazinger and his Great Mazinger not even appearing in full in the "Shin" anime.
Wario, Meta Knight, Pit, Olimar, and the Pikmin first appeared in the series as trophies in Melee, then all became playable in Brawl. Bowser Jr. was also a trophy in Brawl (his "brother" Ludwig was also a sticker in the same game) before becoming playable in the 4th game.
The ducks from Duck Hunt appeared in Melee as a trophy (which had two ducks) and a sticker in Brawl (which only had one). They would later team up with the infamous dog from the same game in the fourth installment. Oddly though, this was the first time the dog appeared in a Smash game.
King Dedede was just a background character in Smash 64 and Melee (also having a trophy in the latter), then becoming playable in Brawl.
Several human villagers from Animal Crossing could appear in the background of the Smashville stage before they would be playable in Smash 4.
Squirtle was a stage platform in the Poké Floats stage in Melee (While also having a trophy) before being playable in Brawl as one of Pokémon Trainer's Pokémon. However, like Ivysaur, it was cut from Smash 4 and only appeared in that game as a trophy, while Charizard, another one of Pokémon Trainer's Mons, becomes its own fighter. Fortunately, as every fighter in Smash history is returning, both Squirtle and Ivysaur reappear in Ultimate, again as a 3-in-1 pack with Charizard.
Charizard and Little Mac appeared as Assist characters in the first 2 Smash games and Brawl, respectively. Come the third and fourth installments in the series respectively, and they're upgraded to full-fledged playable Smasher status. (The former was a part of a 3-in-1 pack in their Smash debut, though)
Palutena only appeared in Brawl during a cutscene for the adventure mode and as a background character that appears whenever Pit uses his Final Smash (and 2 trophies, too). She then becomes playable in Smash 4, and because of that, Pit gets a brand new Final Smash.
Wolf started off as only making a cameo in the introduction movie in Melee before eventually becoming playable in Brawl. Then he became a trophy in the fourth game and completely missed his chance of becoming a DLC fighter. As with the case of Squirtle, he comes back to being playable — as every fighter comes back — in Ultimate, complete with his Zero redesign.
The Inklings were a late addition to the trophies and Mii Costumes in 3DS/Wii U but ascend to being playable in the next game.
Daisy first appeared as a trophy in Melee, and as a Palette Swap for Peach (which would continue in Brawl and 3DS/Wii U); then got a sticker and another trophy in Brawl, then a couple of trophies and a Mii Fighter accessory in 3DS/Wii U. She finally makes her debut as a playable character in Ultimate as Peach's Echo Fighter.
Dark Samus first appeared as a trophy and a sticker in Brawl, later became an Assist Trophy and a palette swap for Samus in 3DS/Wii U, and then a playable character as Samus' Echo Fighter in Ultimate.
Chrom featured in Robin's Final Smash and in one of their victory poses (and a cameo in Palutena's Guidance when fighting Robin), as well as a trophy, a palette swap for Ike, and a Mii Swordfighter DLC costume in 3DS/Wii U, before his debut as a playable character in Ultimate as Roy's Echo Fighter.
King K. Rool appeared as a trophy since Melee, as well as a sticker in Brawl and a Mii Brawler DLC costume in 3DS/Wii U, before being playable in Ultimate.
Along with the Mii Gunner having a DLC costume based on her, as well as appearing as a couple of trophies, and an item in Smash Tour, Isabelle was an Assist Trophy in 3DS/Wii U, but later became playable in Ultimate.
Ken appeared as a trophy in 3DS/Wii U as part of Ryu's DLC pack, before becoming playable in Ultimate as Ryu's Echo Fighter.
Piranha Plant appeared as a stage hazard in 64, and as a trophy in Brawl and 3DS/Wii U before unexpectedly appearing as a DLC fighter in Ultimate, in addition to being a stage hazard again in the Mushroom Kingdom stage from 64.
Ridley beats everyone else by a long shot. He's clawed his way up from a rare background cameo in 64's Planet Zebes, to a quick appearance in Melee's opening movie, then showing up as two separate boss battles in Brawl's Subspace Emissary mode before becoming a complex stage boss in For Wii U's Pyrosphere stage. After fans had been requesting Ridley as a fighter for over a decade, Ultimate finally promoted him to playable status.
Min Min is an interesting case, in the base game for Ultimate she was featured as a collectible in the form of a spirit, but was later promoted to a playable character via DLC. There was a precedent for this in 3DS/Wii U, as Lucas and Mewtwo appeared in the base game as collectible trophies and were later added as DLC, however, they were veterans that were playable in a previous instalment, whereas Min Min is the first newcomer with this distinction.
Pyra and Mythra would follow suit, also being promoted from spirits in the base game to playable characters through DLC in Ultimate. They both function as one fighter, but their spirits were separate.
Team Fortress 2 has a habit of ascending characters that appear in promotional material:
Saxton Hale, the Australian C.E.O. of Mann Co., started out as a gag parody of a 1940's Charles Atlas advertisement. The community then embraced him as a Memetic Badass, even giving him a mod where the whole RED team fights him in his honor. Although he never appeared in the game proper (his first canon appearance was in the Jungle Inferno cinematic), he is a major character in the Mann Vs. Machine arc, hiring the mercenaries after they lose their jobs working for RED and BLU.
In the Australian Christmas update, the justification for the characters being sent back in time to DeGroot Keep is that "the Soldier angered a magician." In the next Halloween update, said magician, named Merasmus, is revealed to be the Soldier's roommate (as well as the one responsible for the Demoman having only one eye), and they both hate each other. The Halloween update after that, Merasmus finally loses it and becomes that year's Halloween boss, and this time, he means business.
Thief: The Dark Project had an easy-to-miss text-only mention of Lord Bram Gervasius, a nobleman who is looking to buy any ancient masks and headdresses you find in the mission "The Lost City". In Thief II: The Metal Age, while he still doesn't make a physical appearance, he becomes much more important, as his collection includes some artifacts sought by both Garrett and the Mechanists, and his mansion is the setting of two consecutive missions.
In the Total War series, when an army goes into a difficult battle without a general to lead it, and comes out victorious, the army's captain (up to that point a non-entity) can ascend to General status and become a valued member of your royal family (and a powerful unit in his own right).
The Total War: Warhammer trilogy, being an adaptation of the Warhammer Fantasy universe, did this with several of its faction leaders in different ways:
Markus Wulfhart, Isabella von Carstein, Tretch Craventail, Deathmaster Sniktch, Lokhir Fellheart, Tik-Taq'To, Gor-rok, the Sisters of Twilight, and Drycha were all hero-tier secondary characters in the original tabletop game (Isabella only being fieldable in an army that included her husband Vlad) who were updated to full-blown legendary lords and faction leaders of their species (though Isabella shares her start location with Vlad).
Grombrindal is a character who only existed in non-canonical White Dwarf articles, and was added as a full-time legendary lord for the Dwarfs. Nakai the Wanderer and Ghoritch also originated from old background articles and were promoted to playable characters, the former as a lord and the latter as a hero.
Ariel was originally playable in older editions of the Wood Elf Army Book, but was dropped much later on. With The Twisted and the Twilight DLC, she finally makes her return as a Legendary Hero. Simiarly, Coeddil, a character from the Wood Elf lore, finally makes an appearance as a Legendary Hero.
Much like Ariel, Repanse du Lyonesse was a character from older Bretonnian army books who was later dropped. She makes a surprising return as an FLC for Warhammer II, especially since she originates from 500 years earlier in the setting.
Alberic de Bordeleaux and Helman Ghorst were characters who only existed in a few lines of background lore, both made legendary lords for their respective factions over several named characters who had stats in the armybooks of Bretonnia and the Vampire Counts.
Finally, the entire Norsca and Vampire Coast factions were made by the developers, most of their units based on scattered fragments of lore from across several of Warhammer's Gaiden Game catalogue, roleplaying spin-offs and splatbooks. Their legendary lords came from all over the abovementioned spectrum: Wulfric and Throgg were secondary hero characters for Warriors of Chaos, Luther Harkon is from a White Dwarf article and from a few snippets of lore from the Lizardmen armybooks, and Count Noctilus and Aranessa Saltspite are Canon Immigrants from the Gaiden GameDreadfleet.
Perhaps the biggest instance of this trope is Grand Cathay, a faction that had only existed in background material with no miniatures at all, being promoted to a launch race for the final game in the trilogy.
The Playstation adaptation of Tomorrow Never Dies does this to a minor, one-shot character, Japanese bio-terrorist Satoshi Isagura, who in the film itself was simply referenced during a briefing to be responsible for a toxic gas attack in Tokyo. In the game itself, after Bond recover Gupta's decoder from Carver's plant in Hamburg, Carver instead decide to retaliate by ordering Isagura to launch a second gas attack in Yokohama, prompting M16 to send Bond to Isagura's hideout in Hokkaido to apprehend him. He even serves as a really difficult boss who spams toxic gas bombs on Bond constantly,.
Name any character from Touhou Project that was playable at least once. Chances are she debut as a boss character you only see in one or two stage. Notable examples include:
Ice fairy Cirno. She starts out as a Stage 2 boss of Touhou Koumakyou ~ the Embodiment of Scarlet Devil with no importance to the actual plot at all. She became playable in the ninth part of the series, in a fighting spin-off, got her own spinoff and ended up playable again in Hidden Star in Four Seasons.
An interesting example: one of Alice's spellcards in Touhou Youyoumu ~ Perfect Cherry Blossom is Curse "Eerily Luminous Shanghai Dolls". The artwork shows a single doll. The people who made the fighting games proceeded to have that doll hovering around Alice in her artwork, and the fans immediately decided it was a unique doll named Shanghai. Almost all of Alice's appearances since have had Shanghai floating somewhere near her.
The Grid Bugs from the movie TRON appear in the arcade game adaptation as one of your main enemies in the I/O Tower mission.
The Unreal universe has a lot of this. First are Malcolm, Brock and Lauren, who were simple skins a player could choose on the first Unreal Tournament. Then, Unreal Tournament 2003 showed that Malcolm was the winner of the Tournament, with Brock and Lauren as part of his team. Since that moment, Malcolm is considered the face of the Unreal series. Unreal Tournament 2004 and Unreal Championship 2: The Liandri Conflict also ascended Gorge and Arclite, (and later, many others, through a patch) from the same game.
The WarioWare series has certain characters who were upgraded to main characters in games after they debuted.
18-Volt debuts in WarioWare: Twisted!, and his first few appearances had him exist mainly to serve as a sidekick to 9-Volt, but he gradually came into his own as a standalone character. Smooth Moves has 9-Volt's story focus moreso on 18-Volt, while D.I.Y. Showcase would have him host a stage by himself for the first time.
For her first few appearances, 9-Volt's mom 5-Volt was only shown briefly in shadow, giving only a vague idea of what she looked like. She becomes a fully-designed character in Game & Wario, where she serves as the main antagonist of 9-Volt's "Gamer" minigame. Future games would ascend her even further, treating her as a proper member of the WarioWare crew, with Gold giving her a standalone stage, and Get it Together! featuring her as a playable character.
Fronk initially served as a recurring background character who randomly appeared during certain minigames, but Gold would make him more of a character, establishing him as 9-Volt's pet, with a supporting role in his stage.
After only one showing in one mission set, for an add-on to Wing Commander II, Jason "Bear" Bondarevski goes on to become a major character in the non-novelizationWing Commander novels, as do, to a lesser extent, several minor characters seen elsewhere in the games, like Janet "Sparks" McCullough and Kevin Tolwyn.
Both The Witcher and its sequel enjoy using this trope. Side characters from the books, such as Triss and Zoltan, get upgraded to main characters in the games, with the former even becoming the protagonist's main Love Interest. Other characters who largely existed as names dropped in the text, like Iorveth, make actual appearances and get fully fleshed out. Understandable given that the games are officially the continuation of the books now, per the original author.
At the very beginning of The Witcher 3: Wild Hunt, Geralt exchanges a few lines of dialog with a vagrant named Gaunter O'Dimm, who gives him a lead on his next quest objective. More than thirty levels and a hundred hours of gameplay later, O'Dimm reappears as the primary antagonist of the Hearts of Stone DLC expansion.
Every pre-WoW bit of Warcraft material had a lot of lore that may or may not have appeared on screen, and may have had little if any effect on the plot, that end up becoming major characters in a later game or when Blizzard needs material for an expansion pack or raid dungeon. In the most extreme example, Sargeras went from a generic bit-part monster to THE Big Bad of the entire universe (albeit a Big Badwho's long dead, as such. Word of God says his spirit is scattered across the Twisting Nether in limbo, but not gone for good).
This has also happened in response to the players falling in love with random Non Player Characters. For example, Hemet Nesingwary was once a minor quest-giver put in as a Shout-Out to Ernest Hemingway. Players either liked or hated him so much that in the first expansion he was moved to Outland and given more quests, and in the second there is an entire faction devoted to fighting him, a third of an area taken over by his crazed former compatriots, as well as yet another group of quests from Nesingwary's hunting party.
High Overlord Saurfang, pre-expansion, served no purpose in the game or the story except to put Nefarian's severed head on a stick and look like a total badass. He was also known for being a ridiculously strong, being able to kill multiple max level players at once with his Cleave ability. Because of this, he became known among the fandom as the WoW's equivalent of Chuck Norris, a warrior capable of Cleaving anyone or everything. He's since become one of the most prominent Non Player Characters in the game, even becoming the new racial leader for the orcs after Garrosh was overthrown as the warchief of the Horde. He was later put in a central role in the story of Battle for Azeroth expansion, being partially responsible for starting the faction conflict in the event known as the War of Thorns, which ended in the destruction of the night elf capital Darnassus, and the genocide of the night elves. This results in Saurfang, who feels greatly responsible for the horrible event, to go through a serious case of Heroic BTSD, and to actively seek death on the battlefied. However, thanks to the characters from the younger generation, like the darkspear troll Zekhan and the human king Anduin Wrynn, Saurfang is convinced to instead fight for the future of his world, leading him to form a rebellion against the true culprit behind the faction conflict: the Warchief Sylvanas Windrunner. This culminates in a Mak'gora between Saurfang and Sylvanas, during which Saurfang tricks Sylvanas into publically revealing that the Horde means nothing to her, after which she kills him with dark magic, causing almost the entire Horde to turn against her and forcing her to flee. Afterwards, Saurfang is remembered by both the Horde and the Alliance as the Inspirational Martyr who ended the Fourth War/Blood War.
And the Alliance equivalent of Saurfang, Bolvar Fordragon, started out as a stand-in for the disappeared King Varian Wrynn and earned some major cool points for fighting off Onyxia's entire elite guard. When Varian came back, Bolvar played a major role in the Dragonblight campaign, pulled a Big Damn Heroes for you, and died during the Forsaken betrayal at the Wrath Gate. Later however it was revealed that he had survived and was held captive by the Lich King, who was trying to torture him into submission, intending to turn him into his champion, in place of his original candidate Tirion Fordring. It didn't work. After Arthas was defeated by Tirion and the players, Bolvar took it upon himself to become the new Lich King, essentially acting as the jailor who would keep the Scourge army contained in Northrend so that they could never threaten denizens of Azeroth again, all the while he too would remain trapped within the Frozen Throne. He later returns in Legion, offering to help the Knights of the Ebon Blade in their efforts to defend Azeroth from the Burning Legion. Bolvar later returns as a major character in the Shadowlands expansion. When Sylvanas Windrunner, empowered by a mysterious entity known as the Jailer, arrives to Icecrown Citadel to confront the Lich King, the two battle which ends in Bolvar being soundly defeated. Sylvanas than destroys the Helm of Domination, causing the veil between the world of the living and the dead to shatter, opening the way to Shadowlands, the afterlife of the Warcraft universe. Together with the Knights of the Ebon Blade, Bolvar than leads Azeroth's heroes into the Shadowlands in an effort to close the rift between the two realms and to stop Sylvanas and the Jailer's plans to remake reality.
Nazgrim starts out as a forgettable NPC giving out a handful of quests in one Northrend quest hub, trying to make a name for himself. He seems to have succeeded, since he later appears as the leader of a squad of Kor'kron aiming to lay claim to a new island risen by the Cataclysm. After the mission goes heavily south, apparently his rather clever and valiant efforts to salvage the operation attracted more attention and he's now a general, and leads the Horde (including the player) in Pandaria until the Warchief personally arrives. Later, as Garrosh grows more and more power hungry, Vol'jin starts a rebellion that together with the Alliance forces sieges Orgrimmar. Despite knowing that Garrosh is going too far, Nazgrim refuses to break his oath to his warchief and leads the city's defenses until he is killed by Gamon and the players. He is later brought Back from the Dead in Legion as one of the Ebon Blades new Four Horsemen.
Taken to extreme levels with Chen Stormstout and the Pandaren. Chen was originally nothing more than an amusing piece of April Fool's Day art that was beloved by the developers enough to be given a minor role as one of Rexxar's companions in Warcraft III. His general hilarity and his enigmatic homeland were eventually considered interesting enough to be the focus of an entire expansion of World of Warcraft.
Vol'jin is a crowning example of this happening. He started in Warcraft III as a quest giver before doing a whole lot of nothing in World of Warcraft. That changes with Cataclysm with his speech in the Troll starting zone, in which he tells the then-warchief Garrosh exactly where to shove it. From there his popularity skyrocketed to the point of being named Warchief of the Horde at the end of Mists of Pandaria. Unfortunately his reign didn't last long as he was mortally wounded at the Broken Shore and passed the leadership of the Horde to Sylvanas Windrunner before dying at the start of the Legion expansion. However, developers assured to the concerned fandom, that his story wasn't over yet and so, he returned in Battle for Azeroth expansion as a Spirit Advisor. His story in the expansion revolves around helping the Zandalari princess Talanji to take up her throne and lead her people, as well as figuring out how he was "brought back" and who convinced him to name Sylvanas as his successor. This storyline was than continued in Shadowlands expansion's Ardenweald Covenant's storyline in which it's revealed that a Loa (beings that trolls worship as Gods) named Mue'zhala, an ally of the Jailer, was the one whispering to Vol'jin in his last moments. Later in the campaign, after the player and Vol'jin fail to save Rezan, the Loa of Kings, he transfers the last of his strenght to Vol'jin, making him a Loa which allows him to be resurrected in Ardenweald.
Tirion Fordring counts, too. In Burning Crusade, all he did was give you a few quests. Come Wrath Of The Lich King, however, and he's in charge of pretty much any attacks on the Scourge. In one of the first things you'll likely see him do, he decimates a massive army of Scourge monsters and redeems a whole batch of Death Knights. Later in Legion, he's one of the first to lead the charge against the Burning Legion. However, this time things don't go according to plan. By the time the Alliance and Horde players arrive to the Broken Shore, the Argent Crusade has been decimated and Tirion is held captive by Gul'dan, who than seemingly kills him. Later, the paladins find out that Tirion is Not Quite Dead and attempt to rescue him. Unfortunately, the torture the demons put him through was too much and Tirion dies in the player character's arms though not before passing the Ashbringer and the mantle of leadership to them.
In XCOM: Enemy Unknown, General Peter Van Doorn was little more than the objective of an Escort Mission, but his defiance in the face of his alien attackers and remorse for the loss of his men helped him stand out from similar NPCs. The XCOM: Long WarGame Mod eventually had him join XCOM in thanks for being rescued, and by XCOM 2 he was included in the base game as a Hero Unit.
Jane Kelly from XCOM 2 was originally a Mauve Shirt you get in the tutorial mission where you rescue the Commander, but could die just like any other trooper. In XCOM: Chimera Squad it's revealed that she canonically survived the events of the game and works as the agency's Director and the game's Big Good.
In Xenoblade Chronicles 1, there's a random kid named Teelan who gives you a couple of sidequests in Alcamoth. In the Switch-exclusive epilogue Future Connected, he's elevated to a full supporting character with a major role in the plot.
Cookie Masterson of You Don't Know Jack was first the sign in host for the first 3 games (Yes Sports did come before volume 2) then finally gets in the limelight starting in Movies.
In the series, Dogi the Wallcrusher was at first a minor character who busts Adol out of jail at one point in the first game and disappears until the end of the second game. However, his bravado and infamous wallcrushing skill instantly turned him into a fan favorite and Dogi became the constant companion of Adol who follows Adol in his later adventures, always busting wall at one point to save Adol in each game. And in Ys SEVEN, he is a playable character.
