* ''{{Megatokyo}}'' has Largo and Piro, Red Oni and Blue Oni respectively. Erika is also the Red Oni to Kimiko's Blue Oni, though they occasionally switch places.
* ''Webcomic/SluggyFreelance'' has Oasis and Kusari, two gymnastic assassins of mysterious origin with superhuman and probably supernatural powers. Oasis is basically insane as a result of MindControl gone bad, which involved manipulating her emotional states. She is left impulsive and compulsive about the emotional reactions she was ordered to have before her controller was killed and is often incapable of rational thought. Recently, it's even be discovered that she is pyrokinetic, just adding to her fiery repertoire. Kusari obeys orders unfailingly, possibly also mind-controlled, but is still capable of rational thought and always remains cool. The two look about as identical as they can under their respective outfits considering that Kusari is always masked, but Oasis's most noticeable feature is her fiery red hair, whereas Kusari is always shown in the same bluish-purple outfit. There is [[EpilepticTrees speculation]] that the contrast between the two hides symbolism hinting at their as yet unknown origins.
* TheContinentals: A steampunk murder, mystery, sci-fi, adventure webcomic set in post Jack the Ripper England where Continental Operative Jeffrey Tiffen Smythe is the sophisticated, elegant, intellectual gentleman and his gender bending partner, the adventress Lady Fiona Fiziwigg, is a hot tempered, foul mouthed, do and say as I damned well please malcontnent and proud of it. It's a pairing of mismatched personalities that works surprisingly well as the two investigate a series of brutal "mangling" murders, uncovering a tangled web of intrigue, adventure--and murder!!! Find it [[http://www.theduckwebcomics.com/The_Continentals here]].
* ''Webcomic/ElGoonishShive'' has Tedd and Susan, sort of. In this case, it's more of a personality difference as Tedd is generally upbeat and unobservant while Susan is a DeadpanSnarker. Other characters lean towards both sides, but generally hover in the middle.
** Another notable example is [[DefrostingIceQueen Susan]] and [[LovableAlphaBitch Diane]]. A strange case, because they haven't actually met, but [[spoiler: they're actually separated-at-birth identical twins who share a few traits but are generally DifferentAsNightAndDay]]. For bonus points, Susan wears a lot of blue and dyed her hair dark blue, whereas Diane's wardrobe is more red and she has naturally blonde hair.
* Hanna and Zombie from ''HannaIsNotABoysName'' are a good example: calm, stoic Zombie (Blue) and impulsive, extroverted Hanna (Red).
** Also works with a HotBlooded, uninhibited Casimiro and disciplined, well-mannered Finas. Even their color schemes are red and blue respectively.
** There's also Doc Worth's {{Jerkass}} red to Lamont's nice guy blue. Although it's been shown that if anybody can get Lamont to lose his cool, it's Worth.
* Krushcor and Beryun from ''TheGodsOfArrKelaan'', they are respectively [[BloodKnight the God of Battles]] and [[TheStrategist the Goddess of War.]]
* ''FetchQuestSagaOfTheTwelveArtifacts'' has [[ActionGirl Saffron]] [[RebelliousPrincess Lachesis]] and her twin Nephilim. No guesses as to [[http://www.fetchquest.com/archive.php?chapterid=7&comicid=6 who's who]].
* ''Webcomic/{{Misfile}}''. Ash and Emily. They even have the correct colored hair.
* ''Webcomic/{{Homestuck}}'':
** [[TheStoic Dave Strider]] is the Blue Oni to [[NiceGuy John Egbert]]'s Red Oni, though their [[ColorCodedCharacters associated colors]] are kind of inverted. (Dave is Red/fire, John is Blue/air.)
*** By the end of Act 5, though, they've pretty much switched places.
** Karkat Vantas (red) and Jack Noir (blue) also have traces of this during their team-up in Act V, minus color correlations[[note]]because trolls think fashion is stupid and Jack '''[[MeaningfulName Noir]]''' is big on black[[/note]]. Karkat is impulsive, loud, and almost always angry at something, while Jack is cool, quiet, and moves with a chilling economy of effort.
** Karkat, again, plays Red Oni to John's Blue once they start interacting. Their colour correlations match up as well, and Karkat's first conversation (from his perspective) with John is a textbook example - Karkat is a raging, capslocking, furious, hateful mess, while John responds with a cheerily oblivious "hi karkat!".
** Vriska Serket, a [[LargeHam hammy]] SociopathicHero, plays Red Oni to Terezi Pyrope, a ManipulativeBastard master {{troll}}.
** Also, cheerful, perky Jade (Red) to grim, dour Rose (Blue). Rose ends up playing Blue Oni to a lot of people, really; she's just about as blue as it is humanly possible to be.
** Equius Zahhak, a [[TheStoic stoic]] traditionalist, plays Blue Oni to the Red Oni antics of Nepeta Leijon, a [[GenkiGirl genki]] roleplayer.
** [[TheDragon Doc Scratch]] is a calm, [[SmugSuper smug]], [[ManOfWealthAndTaste gentlemanly]] {{chessmaster}}, while his boss, [[BiggerBad Lord English]], is a brutal, incredibly destructive demon that very much looks the part. WordOfGod says this was intentional.
** Sollux Captor, due to his bipolar mood swings, plays this trope with himself. Later he mellows out and starts playing the blue to Karkat's red.
* {{Juathuur}}. Dejoru is dark-haired, calm, and compassionate, with the talent to become a healer. Ratheel is loud, fun-loving, has red hair, and fights by making stuff explode. Partly subverted as [[spoiler: Dejoru is capable of releasing an enormous amount of raw energy. Ratheel, on the other hand, is completely useless in each and every fight we see.]]
* Xykon and Redcloak from ''Webcomic/TheOrderOfTheStick''. The former is an FauxAffablyEvil OmnicidalManiac who revels in his own ChaoticEvil nature, whereas the latter is a WellIntentionedExtremist who wants to bring prosperity to his race and whose alliance to Xykon is more a strategical move than anything else.
** Redcloak's true red oni was [[PostHumousCharacter his brother Right-Eye]], however. ''StartOfDarkness'', in which Right-Eye is still alive, repeatedly lampshades it.
** [[LovableRogue Haley]] and [[ActualPacifist Celia]] also count.
** Varsuvius could be seen as the blue oni to Elan's red oni.
** The Order could be seen as three Red Onis (LovableRogue Haley, {{Keet}} Elan, and BloodKnight Belkar) and three Blue Onis (TheSpock Vaarsuvius, TheStoic Durkon, and StraightMan leader Roy).
** The Lawyers: Phil's red to Mr. Jones' blue. There is something of an inverted lampshade hung on this; Phil wears a blue tie and Mr. Jones wears a red tie.
** [[KnightTemplar Miko]] also plays the red to both [[GeniusBruiser Roy]] and [[TheWisePrince Hinjo]]'s blue
** Girard Draketooth's red to Soon Kim's blue. Heck, Girard's a ''redhead'', and Soon comes from ''Azure City''.
* ''WebComic/OzyAndMillie'': Ozy blue (well, grey furred) and Millie red. Helpful that both are foxes.
* ''Webcomic/TowerOfGod'':
** Quant, the [[DarkSkinnedRedhead Dark-skinned]] FieryRedhead with [[PsychopathicManchild anger management issues]] and [[SmallNameBigEgo an ego]] [[StarScraper the size of the Tower]]. He is too proud to ever openly admit a mistake of his and thus comes up with pretexts when it comes to doing the things he secretly wants to. Like staying with Lero-Ro, his longtime fellow Ranker who once climbed the Tower with him. He is reserved, calm, quiet and patient, unless you start bugging him to much. Unlike the rather BookDumb Quant he spends a lot of time thinking, especially when he notices that something is going wrong on the Second Floor, which he can't ignore due to his righteous nature (Quant is more of the self-righteous kind). He is also rather sophisticated and a passionate collector of gramophones.
** [[TheLancer Koon]] [[MagnificentBastard Agero]] [[TheSmartGuy Agnis]] and [[BigGuy Rak]] [[TheHeart Wraith]][[BloodKnight raiser]], Baam's closest friends in the Tower. The former is a scheming, cheating chessmaster with a lot of brains and some trust issues, the latter a [[PettingZooPeople a giant]] [[NeverSmileAtACrocodile bipedal alligator]] who just wants to fight, plain and simple, which describes his world view and how he stomps through life, though, unlike Koon, he never lies (though he is a bit of a firendship-type {{Tsundere}} for Baam). Koon's color scheme is blue, Rak's is red.
* In ''WebComic/GirlGenius'', we have the upbeat, charismatic Gil and the dour, calculating Tarvek. An interesting example in that they're both [[ScienceRelatedMemeticDisorder Sparks]], both schemers by admission, and both part of a LoveTriangle with Agatha.
* ''WebComic/GunnerkriggCourt'' has an interesting example, where we were introduced to a red-haired EmotionlessGirl (Annie) who befriends an impulsive gung-ho girl (Kat). Mutual CharacterDevelopment, however, has by now reversed the roles almost completely.
* Arguably, Sabrina and Zig Zag from ''WebComic/SabrinaOnline'', the former being a somewhat reserved computer/''{{Transformers}}'' nut and the latter an outgoing porn star legend.
* ''ElfBlood'' has the [[spoiler:KO Twins]]: SKO is the Blue Oni, being an adherent of law, order, and obedience, whereas TKO is the Red Oni, being the runaway renegade with a passion for freedom. Judging from a photograph taken when they were in school, however, this dichotomy may have been inverted in the past.
* In TwoGuysAndGuy, Guy (and occasionally Wayne as well) is the red to Frank's blue.
* The Wing Antivirus corporation from ''Webcomic/ElectricWonderland'' has modest (blue) Nathaniel Wing as software developer and his meglomaniac (red) wife Nina as CEO.
* Kaustos and Two, Heiwa and Nandin, and others from ''Webcomic/UniversalCompass''. Almost every character has a foil because they are based off of emotions.
* In ''NextTownOver'', John Henry Hunter is a [[PlayingWithFire pyrokinetic]] outlaw with a suave demeanor and a zest for life, while Vane Black is a stoic, melancholic woman who eschews all pleasure and relations in her quest to kill Hunter.
* In ''Webcomic/TheSilverEye'' Enel is the red oni to Apen Shephard's blue oni, with Enel being the more laid-back and emotionally driven one, and Apen being the more serious and emotionally repressive one.
* ''4Komatose'' stars Ariake Shikima and Kyushu Miyamoto. Their hair, clothing and even speech balloon borders are red and blue, respectively.
* Many examples in ''TheWordWeary'', the most obvious being Grace and her room mate, Gary. This is especially evident after she dyes her hair red while Gary's is bright blue. Grace is angry, cynical and open about it, Gary seems calmer and tries to find the humor in bad situations, noticeably after Gary and his boyfriend break up. Other examples include John and Sam vs. Jason and Yorick, and Elly vs. Harry.
* Muse, the rather energetic superheroine of ''Webcomic/HelloWanderingStar'' is the Red Oni to the Blue Oni of Logo, who believes in the power of meditation.
* Nina is Red Oni to Deirdre's Blue Oni in ''Webcomic/{{Threading}}''.