%% ZeroContextExample entries are not allowed on wiki pages. All such entries have been commented out. Add context to the entries before uncommenting them.
This is a list for the [[LoadsAndLoadsOfCharacters large and varied cast]] of Nickelodeon's ''HeyArnold''.


!!Students of P.S. 118

-> Voiced by: J.D. Daniels (pilot); Toran Caudell (first 26 episodes and "What's Opera, Arnold?"); Phillip Van Dyke (seasons 2 and 3); Spencer Klein (seasons 4, 5, and TheMovie); Rusty Flood ("Helga on the Couch" and "Parents Day"); Alex D. Linz ("April Fool's Day" and "The Journal")
The titular main protagonist.
* TheAce: He can do anything. By the time of the movie, most of the neighborhood believes he can save them from having to sell up and move. And he does.
* AdorablyPrecociousChild: Arnold is one of the most mature animated pre-teens ever imagined.
* AllLovingHero: He never opts for violence, and rather have everyone get along.
* AnimeHair: It's spiky, and lampshaded a lot throughout the series. In fact, it's so iconic, that's it's weird to see him have it combed or hidden beneath a hat ("Helga Masquerade", "Married").
* {{Badass}}: He's accomplished many a great feat in his life.
* BadassPacifist: Most of his AwesomeMoments are done this way.
* BelligerentSexualTension: With Helga.
* BlitheSpirit: Most of the time, he does some miracle with someone's life.
* CharacterizationMarchesOn: He was more eccentric and naive early on. Midway in Season 3, this began to change (although he's still a bit dense).
* ChickMagnet: Arnold has had three girls like him over the series.
* CloudCuckooLander: In the early seasons, anyway, this went away halfway through the first season.
* TheConscience: To everyone, especially in later seasons.
* DeadGuyJunior: He was named after his mother Stella's late father.
* DoggedNiceGuy: When he realizes that he likes Lila.
* TheEveryman: Eventually in the later seasons.
* {{Flanderization}}: His natural desire to help people and incorruptible personality really took over.
* FourTemperamentEnsemble: The Phlegmatic.
* GenerationXerox: In "Girl Trouble," it's revealed his grandparents had a relationship very similar to the one he has with Helga when they were younger.
* GirlOfTheWeek: Although some crushes have lasted through at least a season (Ruth [=McDougal=] and Lila Sawyer), he's had minor crushes not far in-between, like Maria, a sixth grader and Miss Filter, a substitute teacher.
* GreenEyes: According to a poem by Helga.
* HairOfGoldHeartOfGold: Spiky, blonde hair + NiceGuy + AllLovingHero.
* TheHeart: His kindness and determination are what's keeping the town together.
* HeroesWantRedheads: He has a crush on the auburn-haired Ruth and later on the bright redhead Lila.
** But according to Phoebe in "Ruthless," Ruth's hair is chestnut.
* HeroicBSOD: In the episode, ''Parents Day'' when Big Bob makes fun of Arnold's missing parents by calling him "Orphan Boy". Arnold then gets depressed for the rest of the day until he goes to sleep and realizes how much his grandparents have filled the gap his real parents left.
* HeterosexualLifePartners: With Gerald.
* HumiliationConga: Happens to him in the episode "Arnold Betrays Iggy", when he was forced to wear bunny pajamas in public. There's a reason why this is the most despised episode of the show.
* IdealHero: High morals, NiceGuy, and willing to help anyone, even those who don't deserve it.
* InstantExpert: While it wasn't ever stated how long his martial arts lessons took, he became a Bruce Lee tier {{Badass}} without taking a lifetime of training.
* LivingEmotionalCrutch: Helga says she would probably go crazy if it weren't for Arnold.
* LovingAShadow: With Ruth, but also in general, he easily falls in love without knowing his beloved.
* LuminescentBlush: Gets this ''a lot'' in "Timberly Loves Arnold", where Gerald's [[PrecociousCrush little sister has a crush on him.]]
** Gets this a bit too in "Arnold Betrays Iggy", when he thinks back to Iggy wearing bunny pajamas.
* MasculineGirlFeminineBoy: Feminine Boy to Helga's Masculine Girl.
* MeaningfulName: [[spoiler:It was [[WordofGod confirmed by Craig Bartlett]] that his last name is Shortman.]] He's one of the shortest kids in his class, Being shorter than a good number of his friends such as Gerald, Helga, Sid, Lila, Eugene, etc.
* MoralityChain: To any character who's on the edge of making an immoral decision, especially Helga.
* NiceGuy: His defining character trait. Even when he's not the focus of an episode, he'll usually be the only one who won't make fun of the episode's protagonist.
* NiceHat: He's almost never seen without his little blue hat.
* NoRespectGuy: As shown in "Deconstructing Arnold", his classmates, until the end, don't realize how much wise impact he has on their decisions until after they told him to buzz off with his goody goody righteous personality.
* ObliviousToLove: Arnold is incredibly dense when it comes to figuring out Helga's crush on him. Seriously, he buys any flimsy excuse Helga comes up with to cover up her secret. The one time he didn't buy her excuses was in the movie, and even after Helga flat-out tells him she loves him, he still has a hard time believing it.
* OnlyOneName: The creator ''almost'' confirmed that his last name is [[spoiler:Shortman]], and it's PlayedForLaughs.
-->'''Announcer:''' And the winner is...Arnold...hm. The last name appears to be smudged.
-->'''Stinky:''' That must be you, Arnold, on account of you're the only Arnold in the entire school.
* OnlySaneMan: Amongst his class mates, though Gerald isn't that far behind.
* OrphansOrdeal: He can shrug off most insults, but calling him an orphan will cut him deep. ''Real'' deep. Heck, even [[{{Jerkass}} Helga]] [[EvenEvilHasStandards objects against the idea.]] And whenever the anniversary for his parents' abandonment approaches, he goes dim and it's the only time of the year he wants to be left alone.
* ParentalAbandonment: Living with his grandparents, Arnold's DisappearedDad and MissingMom are not even alluded to for a good portion of the series. We eventually learn they disappeared during a jungle expedition while Arnold was a baby.
* PinkGirlBlueBoy: Blue Boy to Helga's Pink Girl.
* PrecociousCrush: In season 1, he had a crush on Ruth P. [=McDougal=], a sixth grader. In "Crush On Teacher", a season 2 episode, [[ExactlyWhatItSaysOnTheTin he develops a crush on his substitute teacher.]]
* RaisedByGrandparents: Since he was a baby, Arnold was raised by his paternal grandparents.
* ShorterMeansSmarter: One of the shortest kids in his class and also one of the smartest.
* SpoiledSweet: To a much lesser extent than Rhonda and Lorenzo, since he's not actually rich, but he has the coolest room only a kid his age could dream about. [[AllLovingHero And he's the absolute nicest and compassionate guy on the show.]]
* StrongFamilyResemblance: He gets his facial looks and oblong shaped head from his mother, albeit he gets his blond hair from his father.
* TechnologyPorn: His bedroom, which boasts a glass ceiling and any number of fold-out implements operated by remote, including the bed.
* TinySchoolboy: He is the shortest boy out of his group of friends and fits with the adorkable type.
* TookALevelInBadass: In the episode where Pookie teaches him martial arts.
* TragicKeepsake: His hat, which was given to him by his parents. When he loses it in one episode, he's determined to get it back.
* WideEyedIdealist: Always believes in the best possible outcome.
* WiseBeyondHisYears: To the point that just about everyone on the show, including adults and even authority figures, have come to him for advice.

[[folder:Helga G. Pataki]]
-> Voiced by: Francesca Marie Smith; Katie Bartlett ("Helga on the Couch")

* AccidentalPervert: When she snuck into Arnold's room, she was stuck between the the wall the couch folds into. She ended up seeing Arnold disrobe, [[TemptingFate even though she didn't mean to.]]
* AntiHero / AntiVillain: Depending on the episode. Earlier episodes tended to use the latter, while later episodes mostly had her be the former.
* AwLookTheyReallyDoLoveEachOther: With Olga.
* BeautyBrainsAndBrawn: The Brawn to Lila's Beauty and Phoebe's Brains.
* BecauseYouWereNiceToMe: Helga fell in love with Arnold because he was the first person in her life that noticed her and treated her kindly.
** In somewhat of an inversion, this is why she treats Arnold like garbage.
* BelligerentSexualTension: With Arnold.
* BeneathTheMask: She pretends to hate Arnold to hide her true feelings for him, and only expresses said feelings when she's alone. Or she thinks so, and Brainy [[OffscreenTeleportation teleports]] behind her.
* BettyAndVeronica: The Veronica to Lila's Betty for Arnold's Archie.
* BigOlUnibrow: Helga has a thick, black unibrow.
* BlondeBrunetteRedhead: The Blonde to Phoebe's Brunette and Lila's Redhead.
* BlondesAreEvil: PlayedWith. She's not evil ''per se,'' but she's not very nice.
* BreakoutCharacter: Helga grew in popularity due to her compelling CharacterDevelopment. By the end of the series, most people would think ''she'' was the main character instead of the football head due to how much spotlight she had. In fact, the show was meant to have a sequel specifically geared around Helga as the main focus in high school.
* BrilliantButLazy: Though not a perfectionist like Olga, the aptitude test shows she '''is''' nearly as competent.
* BrokenBird: Of the {{badass}} variety. She mentions in one episode that she would probably go crazy if it weren't for Arnold.
* CannotSpitItOut: And when she did it in TheMovie... she took the chance Arnold gave her to deny it.
* CatchPhrase:
** "Criminy."
** "Move it, Bucko!"
* CerebusRetcon: [[HilariouslyAbusiveChildhood Much of her background]] becomes unfunny after "Helga on the Couch".
* ClingyJealousGirl: She often tries to [[RelationshipSabotage ruin Arnold and Lila's time together]] because she wants to be the one going out with Arnold.
* ConsummateLiar: When she has to put up an act, like amnesia in "Beaned" or blindness in "April Fool's Day", she pulls it off very convincingly. Other times, she's an expert at hiding her feelings for Arnold which makes him [[ObliviousToLove completely oblivious]] in the first place.
* ChromaticArrangement: Pink to Phoebe's Blue and Lila's Green.
* CuteBruiser: A nine-year-old girl who can kick butt.
* DeadpanSnarker: Helga is by far the most sarcastic character in the entire series.
* {{Deuteragonist}}: The series also takes a heavy focus on Helga, revolving around her home life, friendships, and love for Arnold.
* DoubleStandardAbuseFemaleOnMale: If her and Arnold's genders were reversed, her abusive tendencies towards Arnold wouldn't be quite as funny.
* DramaQueen: Even taking into account her usual hamminess and issues, she's usually the first person to crack up and go melodramatic in a crisis. (Ironic, considering she's considered the toughest girl in school behind Big Patty.)
--> (when stuck on the other side of town) '''''"Walk!?''''' It'll take ''days!'' We'll ''freeze to death! '''WE'LL GET EATEN ALIVE BY PIGEONS!''' Or worse... ''rats!"''
* EvenEvilHasStandards: Does some nasty things to Arnold, but takes major offense to her father calling Arnold an orphan within ear shot of him. In "Curly's Girl", Helga calls out on Rhonda for embarrassing Curly after dumping him while pretending to be Curly's girlfriend.
-->'''Helga''': I think Miss Rich and Fancy did a number on him. (Referring to Curly.)
-->'''Rhonda''': May I borrow the black paint?
-->'''Helga''': ''(Paints a heart with the black paint.)'' Perfect, it'll match the color of your heart.
-->'''Rhonda''': ''(Annoyed)'' Excuse me!
-->'''Helga''': You heard me Cruella.
** On top of that, once she found out that Summer was using Arnold for personal gain (with the intent on dumping him afterwards), she focused all her efforts on exposing her for his sake.
* EvilLaugh: Has a very impressive one. Not as psychotic as Curly's (but then, who could be), but she gets points for once doing it in a theatre, with ominous music and everything.
* EvilPlan: She explicitly refers to them as such, and she has a ton of them. They nearly always fail in ways that harm her and help those she schemes against.
--> '''Helga:''' [[LampshadeHanging "Why are none of my evil schemes working?!"]]
** Ironically, in "Summer Love", her schemes to sabotage Arnold and Summer's dates ''do'' work, but Arnold catches her gloating about it and [[CassandraTruth won't listen to her when she tries to tell him Summer is just using him.]]
* FailureIsTheOnlyOption: Her AnguishedDeclarationOfLove in TheMovie. Arnold ends up confused about it.
* FemininityFailure: In "Helga's Makeover", she tries to be a girly girl to attend Rhonda's sleepover but reverts to her old self after refusing an avocado cream mask.
* ForcefulKiss: Gives a big one to Arnold in TheMovie.
* FourTemperamentEnsemble: The Choleric.
* FreudianExcuse: The reason for her violent behavior is because she feels neglected by her parents and she feels she has to be aggressive to get any respect.
* GeniusBruiser: She is already fairly known among her classmates as a formidable bully. She's also a talented writer/poet, and quite intelligent for her age.
* TheGloriousWarOfSisterlyRivalry: With Olga.
* HairDecorations: She always wears her trademark pink bow, presumably because Arnold complimented it when they first met.
* HatesBeingTouched: Or does she?
-->'''Arnold''': (After Helga finds his hat.) Thanks Helga! Thanks a lot! (hugs her)
-->'''Helga''': (Sighs dreamily before switching back to bully mode.) Yuck! Who said you could touch me?
* HeterosexualLifePartners: Her and Phoebe - mirroring Arnold and Gerald.
* HiddenDepths: Aside having a HiddenHeartOfGold, she's really good at poetry for a nine-year old.
* HiddenHeartOfGold: When she sometimes performs sacrifices for Arnold's happiness, or when she shows genuine kindness for Phoebe.
* HilariouslyAbusiveChildhood: At least until "Helga on the Couch".
* {{Hypocrite}}: What Helga feels and how Helga acts are always opposite things.
* ICallItVera: Named her fists "Ol Betsy" and "The Five Avengers."
* ImpliedLoveInterest: Regulated to this, considering we never got The BigDamnMovie that, among other things, makes her and Arnold an OfficialCouple.
* ImprobableHairstyle: Her hair looks like brooms.
* InferioritySuperiorityComplex: The reason for bullying other children, [[AndZoidberg and Arnold]], is to cover up her crush for him and not be bullied by other children for her exterior, plus that her home life is bad enough as it is. Claimed by herself during her gushing sessions about Arnold, she finds it very hard to overcome her shyness and doesn't quite know how to express her feelings since she had never been shown genuine affection (save Arnold) her whole life.
* InLoveWithLove: Requited or not, pining itself is important to her.
* JerkassFacade: She does care about people, even if she doesn't show it.
* JerkWithAHeartOfGold: She's mean, but has compassion deep down, even helping Arnold out of love several times.
* TheLadette: A pre-teen version.
* LargeHam: A running gag is her tendency to break into overly melodramatic monologues whenever she does anything she regrets, as well as villainous monologues when she's scheming. Often complete with theatrical music.
* LikeParentLikeChild: Personality-wise, she actually has a lot in common with Big Bob, but Helga is much more articulate and emotional.
* LittleMissSnarker: A nine-year-old girl with the dry wit of someone thrice her age.
* LoveConfession: Finally confesses her love to Arnold in The Movie.
* LoveConfessor: Confesses her secret to Lila in "School Play" and Dr. Bliss in "Helga on the Couch".
* LovingBully: The poster girl. Despite being a bully towards Arnold, she's madly in love with him.
* MasculineGirlFeminineBoy: Masculine Girl to Arnold's Feminine Boy.
* MeaningfulName: Craig Bartlett chose Helga's name to emphasize her two sides:
** "Helga" sounds very much like "hell girl", emphasising Helga's mask.
** The name actually means "holy, sacred, successful", which emphasises Helga's hidden softer side.
* MotorMouth: She can really rattle off when she wants to, particularly when giving orders to Phoebe.
* MysteriousMiddleInitial: What precisely the "G" stands for is never revealed in-series; it's actually short for "Geraldine", as a tribute to then-{{Nickelodeon}} executive Geraldine Laybourne.
** Considering how many times she's diminuatively called Gerald "Geraldo"...
* TheNicknamer: She has a name for everybody.
* OffhandBackhand: Helga frequently does this to Brainy.
* PerpetualFrowner: About 90% of her screentime has her frowning.
* PetTheDog: Several times, like in "Arnold's Christmas".
* PinkGirlBlueBoy: Pink Girl to Arnold's Blue Boy.
* PinkMeansFeminine: Subverted. She wears a pink dress as well as a pink bow in her hair but she's rather tomboyish.
* TheReasonYouSuckSpeech: Helga is pretty good at these; she gives a pretty cutting one to Miriam about her being a "lousy mom", and one to Harold after he gets them lost.
* ShadowArchetype: Helga is, [[{{Irony}} ironically]], Brainy's shadow.
* SheCleansUpNicely: Most of the time she doesn't care how she looks, but when she tries (and knows what she's doing) she looks gorgeous.
* SingleTargetSexuality: Never shows the slightest interest in anybody but Arnold.
* SingleWomanSeeksGoodMan: Her feelings for Arnold started when he shared his umbrella with her in the pouring rain and gave her his snacks in preschool. Throughout the series, Helga comments on how she loves his noble, kindhearted side.
* SlapstickKnowsNoGender: Very often. [[DeconstructedTrope Deconstructed]] in "Helga on the Couch".
* SourOutsideSadInside: Helga is a cynical, [[PerpetualFrowner always frowning]] kid. But that's mostly due to her [[TheUnfavorite sad]] [[AbusiveParents childhood]].
* SpotlightStealingSquad: More episodes focused on Helga than any other character except for Arnold, and that's ''not'' including the ''many'' Arnold/Helga episodes.
* StalkerShrine: She built a shrine of Arnold that provides the Trope picture, including pictures she took him.
* StalkerWithACrush: To Arnold. She has a shrine, a statue made out of his chewed bubblegum, and several books of poetry dedicated to him.
* StealthExpert: Has broken into the boarding house a total of ''seven'' times throughout the show's run. All occasions wearing her usual [[HighlyVisibleNinja pink and white clothes]]. There was also the episode where she attempts to sabotage Lila and Olga's friendship where she dressed accordingly.
* StepfordSnarker: Due to her backstory.
* StrongFamilyResemblance: Unfortunately, she gets her looks from her father, making her not so attractive.
* TomboyAndGirlyGirl: Tomboy to Phoebe and Lila's Girly Girl.
* TomboyWithAGirlyStreak: For all her tomboyish and violent personality, Helga always wears pink dresses, her room is filled with girly stuff and is a hopeless romantic.
* TookALevelInJerkass: She's crueler than usual in "Girl Trouble" and "Helga and the Nanny".
* TookALevelInKindness: At the end of "Arnold & Lila" and "Summer Love", and ''especially'' in "Arnold's Christmas".
* TownGirls: The Butch to Phoebe's Neither and Lila's Femme.
* {{Tsundere}}: Type A. She bullies Arnold outwardly but Gushes over him when she believes to be alone.
* TheUnfavorite: Helga is often ignored by her parents in favor of Olga.
* UnknownRival: Lila has no idea that Helga hates her at all, let alone why. Ironically she likely wouldn't want to be considered Helga's rival for Arnold's affections at all, since she doesn't reciprocate.
* UnsympatheticComedyProtagonist: She's often abrasive, and gives others (especially Arnold, her secret crush) a hard time. However, many of her flaws stem from an unhappy childhood as TheUnfavourite. Often times, she still remains the OnlySaneMan among classmates, lamenting their stupidity.
* VitriolicBestBuds: Type 1 with Phoebe. As Helga is bossy, while Phoebe just goes along. The two have a close friendship despite this.
* VocalEvolution: As her voice actress aged, Helga's voice deepened to the point that she sounds like a grown woman in the last few episodes. Oddly, it actually fits her character better.
* WellDoneDaughterGirl: She wants her the approval and attention of her parents (particularly Bob), but she rarely ever gets it due to being TheUnfavourite.

[[folder:Gerald Johanssen]]
-> Voiced by: Jamil W. Smith

Best friend to Arnold.
* AwLookTheyReallyDoLoveEachOther: Like Helga, he clashes with his older sibling, Jamie O., but in "Jamie O. in Love", Jamie O. gets a girlfriend, causing Jamie O. [[LoveMakesYouDumb to act like a happy]] ExtremeDoormat, which Gerald takes advantage of, but when it turns out she is just using him, Gerald begrudgingly tells him the truth.
* BeehiveHairdo: It's apparently an exaggerated hi-top fade, a style that was popular in the 90s.
* BerserkButton: He gets ''really'' angry with [[BigBrotherBully Jamie O]] when he thinks he's trying to "steal" [[OneshotCharacter Chloe]].
* BetaCouple: Is often paired with Helga's best friend, Phoebe.
* BlackBestFriend: To Arnold.
* BrutalHonesty: He doesn't bat an eye to tell Arnold what he thinks of his opinions.
* DeadpanSnarker: The snarkiest character, next to Helga.
%%* FourTemperamentEnsemble: The Sanguine.
* HeterosexualLifePartners: With Arnold.
* TheLancer: The more fun-loving best friend to the much more serious Arnold.
* LargeHam: Any time he's in front of a crowd. Does everything from reciting cheesy UrbanLegends to reading a list of fun things to do on Saturday with all the passion and soul of a gospel preacher.
%%* LovableJock: He's into sports.
* OnlySaneMan: Along with Arnold, he's more down to earth than the rest of the fourth grade class and some of the adults as well.
%%* SoulBrotha
* ShipTease: Occasionally with Phoebe.
* TheSmartGuy: Generally is one of the most informed and competent of the kids.
* TheSocialExpert: He is an extremely convincing businessman, gives Arnold dating advice and, of course, is a talented [[TheStoryteller performer]] when necessary.
* TheStoryteller: Whenever an urban legend or old story needs to be told, Gerald fulfills this role. He is "the keeper of the tale" for many tales.
* VocalEvolution: Jamil's voice broke in season 3, so from that point on his voice had to be digitally pitched.

[[folder:Phoebe Heyerdahl]]
-> Voiced by: Anndi [=McAfee=]

Best friend of Helga. Half Japanese girl who was born in Kentucky but moved to the city at a very young age.
* {{Adorkable}}: A nine-year old nerd with glasses and a friendly personality.
* AsianAndNerdy: She's half Japanese, and a bookworm with the highest grades in the class.
* BeautyBrainsAndBrawn: The Brains to Lila's Beauty and Helga's Brawn.
* BerserkButton: She seems to have a mild one connected to when someone outperforms her academically or socially. In "Phoebe Cheats," she plagiarizes a poem for a contest presumably because Sheena got a higher grade than she did, and because she wasn't chosen as a Student of the Month.
%%* BetaCouple: With Gerald.
* BewareTheNiceOnes: Pushing her around too much is not a good idea.
%%* BlindWithoutThem
* BlondeBrunetteRedhead: The Brunette to Helga's Blonde and Lila's Redhead.
* BrainyBrunette: The Smartest girl her class and gets Straight As.
* BrokenPedestal: She was crushed when she realized Ronnie Matthews was a shallow jerk.
* ButNotTooForeign: Shown to have an Asian father and white mother.
* {{Catchphrase}}: In response to Helga asking her to do something: "[verb]-ing!" In particular, there's...
* CharacterizationMarchesOn: In the first season she was a lot more of a SatelliteCharacter to Helga, to the point of more or less being her shadow and not having much character herself. Later seasons fleshed out her personality more and made her less of a "minion" type.
* ChildProdigy: Getting straight A's in all subjects in school at age 9 makes her this.
* ChromaticArrangement: Blue to Helga's Pink and Lila's Green.
%%* CuteBookworm
* DroppedGlasses: Got knocked off of her once when she was trying to be hall monitor. Unfortunately they got stepped on before she could find them.
* ExtremeDoormat: To Helga. She also has one of these moments in "Ms. Perfect," when she participates in the initial tormenting of Lila. When she gets skipped ahead to the Sixth Grade, she is "befriended" by a group of girls who just want Phoebe to do their homework for them. Helga even points out they're just using her.
%%* FourTemperamentEnsemble: The Melancholic.
* HeterosexualLifePartners: With Helga. They're best friends and she's one of the few people who can stand her.
* HiddenDepths: She's great with a fencing sword and speaks fluent Japanese. Both traits are nurtured by her Japanese-American dad. Also, in "Phoebe Skips" Helga realizes that Phoebe is simultaneously the only girl in school patient enough to really understand her, while also being the only one devious enough to willingly go along with all her pranks.
* KnightTemplar: As a hall monitor. Snaps out of it at the end of the episode.
%%* TheLancer: To Helga, occasionally.
* {{Meganekko}}: A cute girl with glasses
* NiceGirl: Bordering on ExtremeDoormat in her friendship with Helga.
* OutOfCharacterMoment: In "Helga and the Nanny", she along with Arnold, Stinky, and Gerald walk out on Helga upon learning what she did to Inga.
* {{Sidekick}}: Though she hates being treated like one, she often fills this role. As her character is fleshed out more it's shown more clearly that it is due to her being an extremely loyal - and patient - friend.
* OOCIsSeriousBusiness: In "Hall Monitor", when she gained said job, she [[TookALevelInJerkass took Helga's training too seriously ]] to the point Helga had to [[MyGodWhatHaveIDone realize this]] and take action.
* PhraseCatcher: ...this exchange:
--> '''Helga:''' "Oh, and Phoebe? This conversation never happened."
--> '''Phoebe:''' "Forgetting!"
* SecretKeeper: One of the few characters who knows about Helga's crush on Arnold.
* SesquipedalianLoquaciousness: Often speaks with an extensive vocabulary.
* ShipperOnDeck: At the end of "Married", she seems to be a supporter of Arnold/Helga.
* ShipTease: She's implied to have a crush on Gerald.
* ShorterMeansSmarter: The shortest student in Mr. Simmons's fourth grade class, as well as the smartest.
* TheSmartGirl: As a straight A student.
* TomboyAndGirlyGirl: Girly Girl to Helga's Tomboy (One of two).
* TookALevelInJerkass: In the episode, ''Hall Monitor'', she's assigned to be the hall monitor for the week, and becomes more belligerent after being pushed around too much, until she realizes how harsh she's been.
* TownGirls: The Neither to Helga's Butch and Lila's Femme.
* TrueBlueFemininity: Her casual clothing is Blue.
* VitriolicBestBuds: Type 1 with Helga (receiving end).
* VocalEvolution: Her voice is noticeably lower in Season 1, especially in "Operation Ruthless".

[[folder:Rhonda Wellington Lloyd]]
-> Voiced by: Olivia Hack

One of the most popular kids in school and self-proclaimed "fashion queen", Rhonda is spoiled, rich, obsessed with fashion, and a bit of a snob, but she does have a friendly side that comes out quite often. Her best friend is Nadine, but she's often seen hanging out with Arnold and the gang. It's implied that she and Harold like each other, and Curly likes her too... [[AbhorrentAdmirer much to her chagrin]]. She's also a surprisingly good football player.
* AlphaBitch: Very often thinks she's better than everyone because her family's rich.
* BelligerentSexualTension: With Harold, as implied by several episodes that pair them up.
* BreakTheHaughty: All the freaking time, but most notably ''Rhonda's Glasses'' and ''Rhonda Goes Broke''.
* CoolKidAndLoserFriendship: The cool girl to Nadine's loser.
* FallenPrincess: This is the subject of a couple episodes (most notably "Rhonda's Glasses" and "Rhonda Goes Broke"), but she's always back on top by the end.
* TheFashionista: What she aspires to be.
* CharacterizationMarchesOn: Just like the other kids her personality was undefined and she was more of a background character, however by the second season she is shown to be a rich spoiled fashion queen.
* HeroicBSOD: When her family becomes poor in [[ExactlyWhatItSaysOnTheTin "Rhonda Goes Broke"]] - specifically, when everybody finds out that she's poor - Rhonda has a major one, spending all her time in her room miserably crying. Luckily, Arnold reboots her when he talks some sense into her and asks if being rich is ''all'' she's about.
* HypocriticalHumour: In one episode, she tells Nadine she has to have a "three shoe rotation" in order to continue hanging out with her, even though all the characters in the show, including Rhonda, have a LimitedWardrobe.
* JerkWithAHeartOfGold: She does have a good heart under her vain, self-centered exterior.
* LargeHam: She's pretty prone to this when she breaks into histrionics, especially in the episode "Rhonda Goes Broke".
* LovableAlphaBitch: Despite often being a typical spoiled rich girl, she does have a kind side. Not only does she always do the right thing in the end, but her best friend - Nadine - is middle-class.
* {{Meganekko}}: In "Rhonda's Glasses", where she ends up having to wear glasses after a vision test says she needs them.
* NoodleIncident: According to "Egg Story", something happened between her and Harold at the Cheese Festival, but [[TheUnreveal we never find out what.]]
* RichBitch: On her worst days.
* SpoiledSweet: On her best days.
* TomboyAndGirlyGirl: Girly Girl to Nadine's Tomboy.
%%* {{Tsundere}}: For Harold.
* TheUnreveal: So...what happened between Rhonda and Harold at the Cheese Festival?
* UnwantedGlassesPlot: Gets them in ''Rhonda's Glasses'', but later replaces them with cooler glasses, and eventually contacts.
* VocalEvolution: Her voice became more mature in later seasons, this is because her voice actress Olivia Hack was going through puberty. Unlike others on this list, it's barely noticeable.

-> Voiced by: Lauren Robinson

Nadine is Rhonda's best friend, [[OddFriendship even though they couldn't be more different]]. She is fascinated by bugs and arachnids.
* ButNotTooBlack: In a FreezeFrameBonus in Parents Day, Nadine's parents are shown to be a black mom and a white father.
* CoolKidAndLoserFriendship: The dork to Rhonda's cool.
* DarkSkinnedBlonde: She is AmbiguouslyBrown, and yet has blonde hair. This is actually shown in the parents' day episode when one of her parents is black.
* FreakyIsCool: Yay, bugs!
* FriendToBugs: She's fascinated with insects and even studies a lot about them.
* GirlishPigtails: Though they're meant to resemble spider legs.
* HairDecorations: Wears two pink hair clips that make them look like spider eyes.
* OddFriendship: Despite having an interest in insects, her best friend is the snobby Rhonda.
* OnlyOneName: Like many others, Nadine's last name is never mentioned.
* SatelliteCharacter: To Rhonda.
* TomboyAndGirlyGirl: Tomboy to Rhonda's Girly Girl.

[[folder:Harold Chaim Berman]]
-> Voiced by: Justin Shenkarow

A fat kid who's been held back a few grades. Occasionally, a bully.
* BareYourMidriff: He's so fat his shirt doesn't fit properly.
* BerserkButton: Yeah, keep calling Patty "Fatty Patty." That's a good way to induce Harold's biggest screaming meltdown of the series.
* BigEater: One of his main traits, as Helga once claimed [[UpToEleven he ate half his weight in chocolate.]]. He even gets into trouble in one episode because he steals a ham from Mr. Green. When confronted by his parents, he replies, "''I was hungry!''"
* TheBigGuy: Being the oldest of the kids, he shares this role with Helga.
* BigOlUnibrow
* TheBully: In the first season, he was this to Arnold. Though he still has shades of it later on.
* ButtMonkey: Has his moments.
* CatchPhrase: ''"Madame Fortress Mommy!"'' [[ThrowItIn Adlibbed]] by Justin Shenkarow once to Craig and everyone's amusement. They kept writing it in after.
** "Aah Mommy!"
* DumbMuscle: The strongest of the kids, but is 13 years old because he was HeldBackInSchool.
* HeldBackInSchool: Is about 13 years old (old enough to have a bar mitzvah) but still in 4th grade.
* HiddenDepths: Usually with Harold what you see is what you get. But after a mix up in "The Aptitude Test" results in him believing he's a genius, he starts listening to classical music, correctly solves a math problem in his head, and designs a gazebo/bonsai garden for his family's rooftop.
* HypocriticalHumor: In ''Helga's Masquerade'', he makes fun of Helga for having a BigOlUnibrow, despite the fact that he has one himself.
* InformedJudaism: His Jewish background wasn't mentioned until the episode in which he tries to run away from his own bar mitzvah, though prior to that, it was established he had a mom who acted like a JewishMother.
** In fact, in one of the old claymation shorts, he attends church with Arnold.
* IWantMyMommy: Happens occasionally, usually whenever he gets scared.
* {{Jerkass}}: In the first season.
* KindHeartedCatLover: Surprisingly, but "Harold's Kitty" has him adopting a seemingly stray cat and fawning over it.
* LargeHam: "AAH MOMMY!!!"
* LikesOlderWomen: It depends if Patty was held back like Harold or if she's the same age as him.
* NiceHat: Rarely seen without it like Arnold.
* NoIndoorVoice: Less so whenever he's bummed about something.
* OnlyKnownByTheirNickname: His given Hebrew name is Chaim, but he prefers to be called Harold.
* OutofCharacterMoment: In ''Stinky's Pumpkin'' when Mr. Simmons asks the class what the hullabaloo about spring is, Harold of all people answers by saying "Love is in the air". Although it was said with a tone of sarcasm in it.
* SheIsNotMyGirlfriend: With Patty.
* ShipTease: With Patty, and Rhonda in some episodes.
* TookALevelInKindness: He's kind of a dick in the first season, but he eases up in later seasons showing compassion towards others.
* VagueAge: The writers seem to flip-flop between having Harold a few years older, or the same age as Arnold and his friends. In one episode he is shown to have gone to preschool with them yet in another he turns 13. He could have failed preschool though.
* VocalEvolution: The pitch of his voice remained consistent, but developed a raspier sound post-season 1.

-> Voiced by: Sam Gifaldi; Taylor Gifaldi ("April Fool's Day")

A paranoid boy in a hat.
* ButtMonkey: In earlier episodes.
* CatchPhrase: "Boy howdy."
%%* ChronicBackstabbingDisorder
* CoolLoser: He's got style even if he isn't popular.
%%* TheDandy
* GagNose: Has a very big nose.
* HollywoodVoodoo: Thought he once killed Principal Wartz with a voodoo doll made of soap.
* IconicItem: His white Beatle boots.
* JerkWithAHeartOfGold: His spotlight episodes tend to display him as a paranoid LargeHam who frequently lets his imagination get the best of him or digs himself in too deep and needs Arnold to save him. That said, he does try to make amends for the things he does when he realizes he's gone too far.
* KarmaHoudini: He and Stinky receive ''absolutely no comeuppance'' after learning Iggy's secret, spreading it throughout the school, and then bragging about taking pictures at Arnold's final ordeal to get Iggy's forgiveness.
* LargeHam: Episodes centering around him bring this out, especially "Sid the Vampire Slayer" and "Sid's Revenge."
* MyGodWhatHaveIDone: When he thinks he's killed Principal Wartz with a voodoo doll carved from soap.
* NiceHat: Like Arnold, rarely seen without it.
* OnlyOneName: The second most prominent example on the show, behind only Arnold himself.
* PetTheDog: He's not all bad, however. In one episode, he gets into trouble with Big Gino. When Arnold tells Sid he doesn't have to do what Big Gino says, Gino orders him to give Arnold a swirlie. Sid stands up to Gino to take Arnold's place.
* PoisonousFriend: To Stinky.
* ProperlyParanoid: Exemplified in his spotlight episodes where he goes on to freak out over something he thinks would happen and do everything he can to prepare, like having a nightmare where Stinky was a vampire after seeing a vampire movie. He then goes on to read about vampires and to learn about how to deal with one.
* ScreamsLikeALittleGirl: Especially in his Spotlight episodes.
* ThoseTwoGuys: Is this with Stinky a good number of times.
* TookALevelInJerkass: Around Season 3
* WithFriendsLikeThese: Shares this status with Stinky as two of the worst of the kids besides Helga and Harold. Whereas Helga and Harold both have considerable amounts of depth, Sid and Stinky frequently display LackOfEmpathy and turn on their so-called friends. Notably whenever an episode focuses on Harold, Sid and Stinky whill be there to mock him until he finally gives a BigShutUp and threatens to beat the snot out of them.

[[folder:Stinky Peterson]]
-> Voiced by: Christopher P. Walberg

A kid from Arkansas with a thick Southern accent.
* ButtMonkey: Can be this at times.
* CatchPhrase: "This really bites." and variations of it was prevalent throughout the series. In seasons 3, 4, and 5, he also said "Willikers!"
* CharacterizationMarchesOn: In Season 1, he was more of a mindless lackey to Harold and wore spiky arm-bands. Later on, he was revealed to be a lot nicer and no longer wore the arm bands.
* CountryMouse: In fact, he lives in a wood cabin in the middle of the city.
* DeepSouth: From Arkansas.
* GagNose: Has a ridiculously big pointy nose.
* GreenThumb: In "Stinky's Pumpkin", he successfully grows an enormous pumpkin that is big enough for him to comfortably sit in.
* IJustWantToBeSpecial: Often wishes he was able to be good at something.
* JerkWithAHeartOfGold: He can be obnoxious when he's around Sid and Harold, but his spotlight episodes show that he's more civilized when they're not around.
* KarmaHoudini: Being entirely at fault for Arnold's ordeal in ''Arnold Betrays Iggy'' yet nothing happens to him.
* SimpletonVoice: One episode even had him star in a commercial line-up for Yahoo! Soda because of it.
* TrademarkFavoriteFood: Lemon pudding
* WithFriendsLikeThese: Shares this status with Sid. Although, his spotlight episodes do show he has some depth to him.
* SimpleMindedWisdom: He declined the million-dollar contract because he thinks pride is more important than money.
* StrongFamilyResemblance: He looks a lot like his Dad.
* ThoseTwoGuys: Can be this alongside Sid in a good chunk of episodes he's featured in.
** Could be this with Harold also, on a few occasions such as "Deconstructing Arnold".
* TookALevelInJerkass: Much like Sid, his behavior started worsening in Season 3.[[note]]"Arnold Betrays Iggy", "Hey Harold!" and "Gerald's Tonsils" are all close together in production order.[[/note]]
* ToxicFriendInfluence: He's nicer when he's not with Sid and/or Harold.
* UnfortunateNames: See below. Though the only person in the series who ever seemed to find it to be this was the director from "Stinky Goes Hollywood".
* WhoNamesTheirKidDude: It has been stated in his spotlight episodes that "Stinky" just happens to be his real name. The director from "Stinky Goes Hollywood" even {{lampshaded}} it.
* VerbalTic: "I reckon".
* VocalEvolution: His voice actor went through puberty, and thus, Stinky's voice deepened over time.

[[folder:Eugene Horowitz]]
-> Voiced by: Christopher J. Castile (early season 1); Jarrett Lennon (later season 1); Creator/BenDiskin (seasons 2, 3, and 4); Blake [=McIver=] Ewing (season 5 and TheMovie)

An extremely unlucky kid.
* {{Adorkable}}: His friendly attitude and ButtMonkey status has made him beloved by fans.
* AmbiguouslyGay: His bedroom is [[TastesLikeDiabetes decorated with rainbows and unicorns]] and he seems to enjoy dancing and musicals. He also reacts with horror that he has to kiss a girl in "Romeo & Juliet". (The other boys do too, but Eugene specifically states, "I'd rather not kiss a girl," while the others just laugh.) Also, this dialogue from "Ghost Bride":
-->'''Sid:''' ''(to Curly)'' I can't believe you pulled such a dirty trick on us!
-->'''Eugene:''' ''(to Curly)'' I can't believe how nice you look in that dress.
* AmbiguouslyJewish: His last name being Horowitz.
* BeneathTheMask: "Roller Coaster" shows that despite always trying to look on the bright side, he is depressed because of the other kids considering him a jinx.
* BornUnlucky: He was also born on a Friday the 13th.
* ButtMonkey: Almost every episode has him in some form of pain.
* CatchPhrase: "I'm okay," said after something bad happens to him.
* IronicName: His name means [[BornLucky "born lucky"]].
* TheJinx: The other kids think he is one of these, and Arnold often gets dragged into trouble when he tries to help Eugene or prove that he ''isn't'' a jinx.
** After a while Eugene realizes that some of his worse bad luck incidents (such as his bike being destroyed and his goldfish getting killed) happened when he was around Arnold, [[{{Irony}} prompting him to believe that]] ''[[{{Irony}} Arnold]]'' [[{{Irony}} is the jinx]].
* TheKlutz: Not just extremely clumsy, but is also just a bad luck magnet in general.
* NiceGuy: One of the nicer kids in school.
* ThePollyanna: He is almost always freakishly happy and optimistic, despite his luck issues.
* ScreamsLikeALittleGirl
* StepfordSmiler: In the episode, ''Married'' when he believes that Sheena will be his future wife.
* ThrowTheDogABone: Arnold often tries to invoke this, but each time life tends to [[YankTheDogsChain yank the chain]].
* WideEyedIdealist: Surprisingly, he tends to look on the bright side of everything, no matter how dense the situation is.
* YouthfulFreckles: To match his red hair.

[[folder:Lila Sawyer]]
-> Voiced by: Ashley Buccille

A poor country girl who transfers to the school.
* AllLovingHeroine: Although she came off as an intentional [[ParodySue parody]].
* BeautyBrainsAndBrawn: The Beauty to Phoebe's Brains and Helga's Brawn.
* BeneathTheMask: Not shown too much in the series, but in an interview Craig Bartlett said she had a hidden dark side. However, this calls for a reevaluation of pretty much all her scenes involving Arnold and his unreciprocated crush on her. Her dark side may have very well been there, just hidden under a veil of passive-aggressive sweetness.
* BettyAndVeronica: The Betty to Helga's Veronica for Arnold's Archie.
* BewareTheNiceOnes: It's made pretty clear by WordOfGod that she does have a dark side, though it's been hidden during the show's run.
* BlondeBrunetteRedhead: The Redhead to Helga's Blonde and Phoebe's Brunette.
* BrokenAce: She's smart, funny and charming, but has a horrible home life and poor self esteem.
%%* TheChick
* ChromaticArrangement: Green to Helga's Pink and Phoebe's Blue.
* CountryMouse: Compare her to Rhonda, and you'll know she fits.
* DudeMagnet: She's popular with the boys.
* {{Foil}}: To Helga, big time. A great deal of Lila's appearances, and the nature of Arnold's relationship with both, play up how Lila is everything Helga isn't.
** [[WordOfGod According to Craig]] Lila had a repressed dark side. So in addition, while Lila was sweet and innocent on the outside, but emotionally disturbed on the inside, Helga was mean and crazy on the outside, but kind and sophisticated on the inside.
* GirlishPigtails: Always sporting these.
* HeroesWantRedheads: Arnold has a crush on her but it wasn't requited
* LoveRevelationEpiphany: In "Arnold Loves Lila", Lila starts to like Arnold only because Helga wrote "Arnold Loves Lila" on the wall and Lila assumed it had to be true. Arnold tells her he doesn't "''like''-like her" and Lila becomes very disappointed, but realizes she only came to "''like''-like" Arnold because she thought he felt that way about her. So when Arnold realizes he does "''like''-like her", Lila isn't interested in him anymore.
* ManipulativeBitch: Not to an extreme, but there are times when, looking closely, you see Lila's rather sly. In a subtle way by expressions and choice of words. There's the question of her and Arnold's interactions, plus the fact that she reeled Helga in with no choice but to confess her secret rather impressively in "School Play". With Craig's claims of her having a locked dark side, it makes one wonder.
** When asked about Helga and Lila becoming friends in the future (and if that meant that Helga accepts Olga as well) in The Arun Mehta Show Special With Craig Bartlett, which confirmed the idea was more of [[{{Fanon}} fan canon]] rather than actual canon that he's thought of, he had this to say -
-->'''Craig''': Helga and Lila have a really complex relationship because Lila has helped her keep her secret and helpe--and Lila's a bit of a player, you know, she kind of manipulates people in her--in her sort of innocent way.
* MasterOfTheMixedMessage: Offers a sort of unintentional hope spot for Arnold sometimes, but ends up emphasizing at the end that she does not "''like''-like him"
* MissingMom: She's only raised and supported by her father.
* NiceGirl: An ''ever-so-sweet'' kind girl.
* ParodySue: A sickeningly sweet parody of a MarySue.
%%* PerpetualSmiler
* ThePollyanna: Like Eugene, Lila is very optimistic. In fact, Helga tried to scare her out of the part of Juliet with bad costumes, violence, and stage fright, but she just sees the other side of those things.
* ProperLady: Her politeness is pretty much what makes her character going.
* RedheadInGreen: Usually because of the LimitedWardrobe.
* SecretKeeper: Due to events in "School Play," Helga is forced to confide in her that she loves Arnold. (Naturally, before telling Lila, Helga threatened to strangle her if she ever told anyone.)
* ShesGotLegs
* ShipperOnDeck: Ironically, if mildly. She thinks Helga's crush on Arnold is "ever so sweet" and is more than willing to bow out of the way so Helga can orchestrate a kiss with him.
* StepfordSmiler: Implied, according to WordOfGod.
* SuperDrowningSkills: She can't swim.
* TomboyAndGirlyGirl: Girly Girl to Helga's Tomboy.
* TownGirls: The Femme to Helga's Butch and Phoebe's Neither.
* UnrequitedLoveSwitcheroo: In "Arnold & Lila", when Lila believes Arnold has a crush on her, she starts to like him too, but he "likes her, but doesn't ''like''-like her". Once she gets the message, he really does start to "''like''-like her". Unfortunately, Lila decides that she now just likes him and insists in being JustFriends for the rest of the series.
* VerbalTic: "Ever so", "oh so", and "I'm certain that..."
* WhatDoesSheSeeInHim: For some reason, she goes completely head over heels for Arnold's cousin Arnie.
* YouthfulFreckles: To match her red hair.

[[folder:Thaddeus "Curly" Gammelthorpe]]
-> Voiced by: Adam Wylie; Steven Hartman ("Downtown as Fruits"); Haley Joel Osment ("Deconstructing Arnold"); Michael Welch ("Curly's Girl" and "Ghost Bride")

Psychotic kid with black hair and glasses.
* AbhorrentAdmirer: To Rhonda.
* '''AxCrazy''': He seems to get a high off of causing all sorts of mischief.
* BewareTheQuietOnes: In "Curly Snaps". It was even lampshaded by Helga:
--> '''Mr. Simmons:''' I think we've all learned a valuable lesson here today.
--> '''Helga:''' Yep. Don't ever trust the quiet ones. They'll go bonkers and hole up the principal's office.
* {{Blackmail}}: Does this to Rhonda in "Curly's Girl".
* CreepyChild: Often exhibits TroublingUnchildlikeBehavior.
* DoesThisRemindYouOfAnything: In "Curly Snaps", he, well, [[ExactlyWhatItSaysOnTheTin snaps]], locks himself in the principal's office and throws basketballs at all his classmates who he thinks mistreated him for years. The other pupils react very shocked that the quiet Curly is capable of this.
* DisproportionateRetribution: His actions in ''Curly Snaps'' were because he wasn't picked for Ball Monitor.
* EmbarrassingFirstName: "Thaddeus."
* EvilLaugh: Does this when he's causing chaos.
* ForcefulKiss: Just ''loves'' giving these to Rhonda.
* JerkAss: Probably the most obnoxious of all the kids, which is saying something.
* LargeHam: Whenever he's acting manic, he'll get real emotional.
* LaughingMad: Often as part of his EvilLaugh
* OnlyKnownByHisNickname: His real name is Thaddeus, but everyone calls him Curly.
* OpaqueNerdGlasses: Wears these all the time.
* StalkerWithACrush: To Rhonda.
* TroublingUnchildlikeBehavior: Curly is consistently portrayed as criminally insane.

-> Voiced by: Craig Bartlett

An otherwise taciturn mouth-breathing nerd who seems to have a thing for Helga.
* AbhorrentAdmirer: To Helga.
* AuthorAvatar: WordOfGod has confirmed Brainy is his voice's actor ''other self''.
* BeneathTheMask: Brainy knows who Helga truly is.
* ButtMonkey: He's almost always being punched by Helga.
* CannotSpitItOut: Literally, his VaderBreath asthma never let him say anything more than "Hi Helga" before the OffhandBackhand.
* {{Determinator}}: Nothing can keep him from being near Helga.
* HiddenDepths: As confirmed by [[AllThereInTheManual the sixth book of the series Hey Arnold!]] [[http://www.amazon.com/Arnold-Arnolds-Files-Groening-Bartlett/dp/0439381495/ref=pd_sim_b_3 Arnold's E-Files]] Brainy is as eloquent as Helga… but he can't talk because of asthma, which causes his VaderBreath. Also, he's pretty good at manipulating Arnold, loves poetry, and is allergic to cats.
* InterruptedDeclarationOfLove: It's implied this is what Brainy is trying to say to Helga before [[RunningGag the usual]] OffhandBackhand.
* IWantMyBelovedToBeHappy: WordOfGod says this is how Brainy ultimately feels about Helga.
* OffscreenTeleportation: Being offscreen most of the time, it's pretty easy for Brainy to do this. Lampshaded in several episodes where he shows up behind Helga in the most ''improbable'' places, such as on Elk Island, the [[spoiler:supposedly]] haunted train, and even in an alley that Helga ''made sure'' was empty.
* OnlyKnownByTheirNickname: Everyone calls him Brainy, but his real name is unknown.
* TheQuietOne: He rarely talks when he's onscreen.
* RejectionAffection: While Helga is busy being a StalkerWithACrush to Arnold, Brainy is doing the same to Helga, but a lot more openly. No matter how many times she hits him, he persists. FridgeBrilliance when you realize Brainy knows Helga is the poster girl for LovingBully: ''Helga treats Brainy as bad as Arnold.''
* SatelliteCharacter: To Helga. He doesn't even get his own ADayInTheLimelight.
* ScaryFlashlightFace: In the opening theme, complete with an offscreen scream as he does it.
* ShadowArchetype: Helga is a {{Hypocrite}} with HiddenDepths who denies her feelings. Brainy is a guy with HiddenDepths who always tries to say his feelings (but can't due to having asthma). [[BeYourself Brainy is the one thing Helga wants and fears to be]]. Brainy is Helga's SatelliteCharacter [[FridgeBrilliance because Brainy is Helga's self, and Helga is Brainy's]] ShadowArchetype.
* VaderBreath: He breathes loudly through his mouth.

-> Voiced by: Francesca Marie Smith

* AbhorrentAdmirer: She's good friends with Eugene, but while she's happy about Rhonda's marriage prediction in the episode "Married", Eugene's response is...less than enthusiastic.
* EveryProperLadyShouldCurtsy: When she was announced as having best report in "Phoebe Cheats".
* FragileFlower: Helga manages to convince her to drop out of Romeo and Juliet when she tells Sheena how bloody and sad the play really is.
%%* GenkiGirl
%%* GranolaGirl
* HairDecorations: Has pink hair clips.
* HugeSchoolgirl: Easily the tallest girl in class; towers over many of the ''adult'' characters at only nine years old.
%%* NiceGirl
* OnlyOneName: Her last name is never revealed.
* SatelliteCharacter: One of the few characters to not get ADayInTheLimelight.

[[folder:Ruth P. [=McDougal=]]]
-> Voiced by: Lacey Chabert; Anndi L. [=McAfee=]

* ChuckCunninghamSyndrome: In the first season, she was just a generic love interest for Arnold, but as Arnold grew more of a personality, Ruth faded out of the show without any explanation.
* TheDitz: She thinks Arnold's secret note to her is from a famous poet, named Anonymous.
* SatelliteLoveInterest: Her only role in the show is to be Arnold's crush early on. Effectively disappears after Arnold finds out that they have nothing in common.

[[folder:Patricia "Patty"/"Big Patty" Smith]]
-> Voiced by: Creator/DanielleJudovits

%%* BigOlUnibrow
* DullSurprise: How she speaks. All the time. Which contrasts Harold who is very dramatic and hammy.
* HairDecorations: Wears a blue bow.
* HiddenDepths: Underneath that tough championship arm wrestler outer shell is a polite girl who volunteers at homeless shelters and knits.
* HugeSchoolgirl: Her parents look like midgets next to her.
* InSeriesNickname: Overlaps with EmbarrassingNickname. Most kids call her "Big Patty" even though as Harold says, ''"Her name isn't Big Patty, it's Patty!"'' Once people get to know and respect her, they drop the "Big."
* NoGuyWantsAnAmazon: Played with. [[JerkAss Sid and Stinky]] mock Patty because of her size, saying if they had to dance with someone like her, she'd probably crush them. But Harold, no small fry himself, likes Patty, not because he's an AmazonChaser but because they have a genuine connection, one that leads to them spending all night just talking.
* ProperLady: Shockingly yes, if she would stop beating kids up. Then again she apparently only goes after people who have provoked her.
* SecretKeeper: Implied- In "Helga vs. Patty", she makes an offhanded comment about Helga seeming fond of Arnold. [[{{Tsundere}} When Helga angrily denies it]], Patty just smiles knowingly.
* TomboyWithAGirlyStreak: She is Tough but can be a ProperLady as shown in Polishing Rhonda.
* TrueBlueFemininity: Generally wears Blue clothing.

-> Voice by Victor Cohn-Lopez

* EarlyBirdCameo: His debut episode was supposed to show him as a new character, but he had already shown up in ''Arnold's Room'' and ''Gerald's Tonsils''. Blame Nick's airing order.
* MyBelovedSmother: His mother is very overprotective.
* NiceGuy: Like Arnold, Lorenzo is polite to his friends.
* NoSocialSkills: In ''Rich Kid'', it's shown that he has no idea how to goof off and be a kid.
* SpoiledSweet: He's as rich as Rhonda, and a friendly guy to boot.
* SuperOCD: Arnold even points out how he's always looking at his watch every five seconds. He does get over it.
* WiseBeyondHisYears: He's nine years old, but has the personality of a 30-year old businessman.

-> Voiced by Joseph Ashton

* CoolShades: Wears teal shades and is never seen without them.
* DemotedToExtra: He was already pretty much an extra at the beginning of the show but he had his own episode with ''Arnold Betrays Iggy''. After that episode's terrible reputation, though, he never had a major role again and only appeared in the background in a few episodes and only had a speaking part again 4 years later in the episode ''Gerald's Game'''.
* FlatCharacter: Iggy's main reputation during the time he was on the show was that he was considered the cool kid, though they never explain why.
* ItsAllAboutMe: He doesn't care for the depths that Arnold is going through to earn his forgiveness, and he doesn't even care that he got the wrong guy in the end. In the end, ''Arnold Betrays Iggy'' was all about ''his'' pain and humiliation.
* {{Jerkass}}: Shown to be one for what he puts Arnold through.
* MyGodWhatHaveIDone: What he realizes at the end of ''Arnold Betrays Iggy''.
* TheScapegoat: Is blamed for the events of ''Arnold Betrays Iggy'' when Sid and Stinky are mainly the ones at fault.
* WithFriendsLikeThese: More so than Sid and Stinky combined. Thankfully Arnold realizes this and breaks off his friendship with Iggy.

[[folder:Peapod Kid]]
-> Voiced by Jamil W. Smith

* MadLibsCatchPhrase: "Oh, my, that is terribly, terribly X."
* OnlyKnownByTheirNickname: He's called Peapod Kid because he has no real name given and he dresses as a peapod in the school play.
* ShipTease: In ''Married'', Rhonda predicts that he'll be married to Nadine someday suggesting he has a crush on her.
* SpoiledSweet: He's as rich as Rhonda and a pretty nice guy as well.

!!The Adults

[[folder:Grandpa "Steely" Phil [[spoiler:Shortman]]]]
-> Voiced by: Creator/DanCastellaneta

Arnold's grandfather/ParentalSubstitute.
* AnnoyingYoungerSibling: He acts like this to his older twin sister when she comes over to visit. This lowers after Arnold helps him and Mitzi make peace.
* BadassGrandpa: Defeated Big Bob on in the Parent's Day episode. Also a decorated World War II veteran, even if [[UnreliableNarrator he didn't really beat up Hitler (it was actually Goebbels)]]. It is also said that he can bench 210 lbs, even at his old age and is as healthy as a man decades his junior.
* BelligerentSexualTension: With Gertie when they were younger.
* CassandraTruth: In "Girl Trouble," he flat-out tells Arnold that Helga constantly teases him because she likes him. Arnold naturally doesn't believe him.
* CloudCuckoolander: Not to the extent of his wife, but some episodes play this up to the hilt, such as the one where he believed himself stranded on a deserted island and confused a flock of ducks for his ancestors.
* CloudcuckoolandersMinder: Serves as this to Pookie when he isn't being one himself.
* CoolOldGuy: He's nothing if not a great parent for Arnold, and he's more than willing to bend over backwards to help his grandson.
* GenerationXerox: "Girl Trouble" reveals Phil was teased by Gertie the same way that Arnold is teased by Helga.
** "Snow" also seems to imply that he had a similar relationship with his grandfather that Arnold has with him.
* GenreSavvy: He often describes the plot templates in play.
* GettingCrapPastTheRadar: At least half the instances of it in this show come from him. Chief among them being that he's named after a type of dildo.
* GrumpyOldMan: Not usually, but he has shown shades of this on a few occasions, usually when he is annoyed with the borders.
* NoodleIncident: Phil was apparently an acrobat in a Russian circus.
* ObfuscatingStupidity: Uses this on occasion, most notably in a flashback to his days in WorldWarTwo where he tricks group of Germans who had captured him into eating spoiled meat.
-->"It was then I realized that if I let the Major think he was smarter than me I could make him do anything I wanted..."
* SavvyGuyEnergeticGirl: The Savvy Guy to Pookie's Energetic Girl. While he can be a little ditzy as well sometimes, she's this ten times more than him.
* ThoseTwoGuys: Despite how much he hates Oskar, the two have many scenes together throughout the series.
* VocalEvolution: His voice sounded more raspy and forced in the first few episodes. In the original pilot, Dan's voice sounded similar to what it would post-vocal evolution, but was more shaky.

[[folder:Grandma Gertie (aka Pookie) [[spoiler:Shortman]]]]
-> Voiced by: TressMacNeille

Arnold's grandmother.
* AffectionateNickname: Pookie.
* BadassGrandma: An expert in karate and capable of rescuing a mistreated sea turtle and repairing the subway.
* BelligerentSexualTension: With Phil in her youth.
* CloudCuckoolander: Pretty much embodies this trope as she's often seen acting like a different stock character, such as a cowgirl or a karate master.
* CoolOldLady: She's respected for being fun-loving for her age.
* GenerationXerox: In "Girl Trouble," it's shown that she and Phil had a relationship very similar to Helga and Arnold when they were younger. As part of the gag, Gertie in the flashback is voiced by Helga's voice actress.
* GirlishPigtails: In her youth.
* LetsGetDangerous: She saves the day when even Arnold fails. For example repairing the underground or stopping Bob's bulldozer.
* LovingBully: In her youth.
* NeverMessWithGranny: She's a black belt in karate.
* ObfuscatingInsanity: There are rare times where she behaves in an odd fashion - only to then imply it was just an act.
* OnlyKnownByTheirNickname: Usually referred to as "Grandma," "Pookie" or other nicknames. Her first name is mentioned as part of the GenerationXerox twist in "Girl Trouble."
* OOCIsSeriousBusiness: In "Parents Day," she acts like her usual fun-loving, crazy self. After seeing Arnold so depressed over his ParentalAbandonment, however, she snaps out of the role she was playing and acts far more subdued.
** Played for laughs during a heat wave; Arnold notes that the heat's ''so'' bad that even his grandmother is acting normal. [[spoiler:Her wearing scuba gear and walking around like she does it every day when it starts raining is a sign that everything is going to be fine]].
* SavvyGuyEnergeticGirl: The Energetic Girl to Phil's Savvy Guy. While he can be a little ditzy as well sometimes, she's this ten times more than him.
* ScatterbrainedSenior: She is pretty much insane. Unlike most instances of this trope, played for laughs rather than drama.
* {{Tsundere}}: In her youth.

[[folder:Olga Pataki]]
-> Voiced by: Nika Futterman

Helga's older sister and the parental favorite, much to Helga's dismay (and Olga's too, as revealed in "Olga Comes Home"). At first glance, Olga appears perhaps too perfect: Successful, pretty, smart, and sweet and kind to everyone. But she's actually dangerously neurotic, melodramatic and out of reality, due to having to constantly live up to her parents' (well, her father's, anyway) constant attention and ridiculously high standards.
* AloofBigSister: Unintentionally this to Helga.
* AwLookTheyReallyDoLoveEachOther: With Helga in every single episode she appears in.
* BareYourMidriff: Her default outfit shows it off a bit.
* TheBGrade: Hasn't received an A- since third grade. In the "Olga Comes Home" episode, she cried for days in bed because she saw a B+ on her report card. Turns out, it was Helga who intercepted her report card and changed her grade out of jealousy.
* BrokenAce: She seems to be perfect at everything, but underneath her [[StepfordSmiler façade]] she's incredibly broken due to her father's absurdly high standards for her.
* CoolBigSis: In the aptly-named episode "Big Sis", she becomes one to Lila through volunteer work. With her biological sister Helga, however...not so much, but only because Helga can't stand her. However, Olga's come through for Helga on several occasions.
** Averted in the episode where Olga becomes a teacher's assistant- she proceeds to tell ''the whole class'' that Helga used to wet the bed, [[WhatTheHellHero then gives Helga a detention when she lashes out at all the teasing that follows.]]
* CuteButCacophonic: See TheBGrade above
* EmbarrassingNickname: To Helga- she insists on calling her "Baby Sister".
* ExtremeDoormat: She doesn't even tell her parents how she really feels about the high expectations she's felt she needs to live up to.
* FragileFlower: Her response to anything stressful is to freak out and burst into tears.
* FriendToAllChildren: Regardless of what Helga thinks, her schoolmates love Olga.
* NervousWreck: Underneath her [[PuritySue "perfect girl"]] [[StepfordSmiler façade]].
* NiceGirl: To everyone and shows no contempt toward anyone.
* ParentalFavoritism: On the good end of it, which turns out to [[DeconstructedTrope not be so good for her, in reality]].
-->'''Olga:''' You must think I'm lucky, all the attention I get from them. I have to perform for them all the time like some kind of wind-up doll. I get really sick of it. You're lucky they don't even notice you.
* ThePerfectionist: Mainly because of Bob's high standards for her.
%%* SexySchoolwoman
* StepfordSmiler: Type A. She pretends to be happy around her family, when deep down, she's constantly stressed out from her parents' high standards.
* UnknownRival: She genuinely has no idea Helga has been competing with her for her whole life, and seems genuinely ''shocked'' when Helga tells Olga she can't stand her.
* ZettaiRyouiki: Wears thigh-high socks to match her plaid skirt.

[[folder:Robert "Big Bob" Pataki]]
-> Voiced by: MauriceLaMarche

Father of Helga and Olga. Runs a local business aptly named "Big Bob's Beepers".
* AbusiveDad: Emotionally to both daughters, but in completely different ways.
* AccidentalMisnaming: Consistently calls Helga by her sister's name, and almost always gets Arnold's name wrong.
* AdaptationDyeJob: He has gray hair in the series, but in the movie his hair is brown.
* BigOlUnibrow: Where Helga gets hers from.
* DependingOnTheWriter: Abusive {{jerkass}} or simply an ignorant boor who just doesn't understand how much trouble he's caused for his family? The latter characterization [[CharacterizationMarchesOn became steadily more common from Season 2 and onward]]. In the first season, he was portrayed as pretty much devoid of redeeming qualities.
* TheDragon: To Scheck in the movie, in order to build a bigger Big Bob's Beepers. [[spoiler:Though he defects from Scheck once he finds out that he's getting only 49% of the income.]]
* EducationPapa: Most of the pushing towards excellence that Olga received came from Bob's end, as he was the one who made it a big deal that she win so many awards and trophies, while Miriam just provided commentary. In the early seasons he even tried to shape Helga into following Olga's path.
* FatBastard: Most of the time.
* {{Gasshole}}: He belches and breaks wind on occasion.
* GoshDangItToHeck: Tends to say "Mother Hubbard" and "Heck".
* HumiliationConga: Helga was so disturbed by the "Orphan boy" line (see below) that during a gladiator-style event, she told Phil what Big Bob's weakspot was. Basically, she told him to go for the ankles, which sent Big Bob into a tub of gelatin - costing him the event and the overall win.
** Basically any episode that accentuates his JerkAss qualities ends with him getting a solid block of hilarious karma dropped on his head. "Roughin' It" is another good example, where he ends up alone in his RV stuck with sunburn, swamped with bugs, and itching from poison ivy (not to mention having been electrocuted by his own faulty products earlier) while everyone else enjoys camping the old fashioned way.
** He goes through another in "Summer Love". He sits in a lounge chair, gets sunburned, and has no one to take care of him, not even his wife whom he neglects. When he tries getting out of the house, he irritates his sunburn and gets a defeating blow from Miriam.
* JerkWithAHeartOfGold: While he rarely shows it, he does love and care about Helga, and in some instances can help out other characters when needed. They even hint that he does care about his wife as well, especially in "Summer Love" when she told him about another man teaching her "the Watoosy".
* KickTheDog: His "orphan boy" line (referring to Arnold) in "Parents Day". It's so mean and insensitive that it would qualify as a MoralEventHorizon if he'd said it directly to Arnold (as it stands, he was talking to Helga and was just characteristically loud and uncaring about anyone else overhearing).
* MyGodWhatHaveIDone: In the HalloweenEpisode he was legitimately horrified when he realized he just attempted to murder Helga [[ItMakesSenseInContext thinking she was an alien]], calling himself a monster.
** More so in ''Big Bob's Crisis'' after having a heart attack. [[spoiler: It was actually gas.]]
* NotSoDifferent: Helga gets her more abrasive personality traits from Bob, which allows them to bond in several episodes.
* ParentalFavoritism: To Olga to the point that she would rather be neglected to avoid having to live up to his standards.
* ParentalNeglect: To Helga to the point of ignoring her existence when Helga was about to go to pre-school
* TookALevelInKindness: "Big Bob's Crisis" was all about Bob realizing his high-stress life made him obnoxious, cruel and abusive to those around him - though he initially overcompensates by uprooting the entire family and becoming an ExtremeDoormat, it ends with him deciding that he can be his old self while still being a little kinder and a little less stressed.
** DoubleSubverted in the movie (which takes place after "Big Bob's Crisis"). He's all for getting rich off of the destruction of the neighborhood, until he finds out that [[spoiler:Scheck's getting 51% of his company]]. He later offers to help Phil and the boarders to stop the bulldozers.
* WouldntHurtAChild: He may be a {{Jerkass}} like his daughter and use verbal abuse, but Bob draws the line when it comes to physically harming a child. In the Halloween episode he almost had Helga killed when he thought she was an alien, until he learns that the "alien invasion" was just her in costume for a theme party - at which point he was ''very'' distraught.
** Also happens in "Save the Tree" when he refuses to bulldoze the kids' favorite tree because his own kid is up there.
* WhyCouldntYouBeDifferent: To Helga.

[[folder:Miriam Pataki]]
-> Voiced by: KathSoucie

Mother of Helga and Olga, Miriam is a depressed, constantly sleepy, seemingly ditzy housewife with an addiction to "smoothies" (WordOfGod confirms that all of these are signs that Miriam is an alcoholic, with "smoothies" as a cover-up for booze). It's not uncommon to find her sleeping in strange places. However, she can be very competent and intelligent, but unfortunately it seems that being married to Big Bob has really brought her down.
* TheAlcoholic: The show indicates she drinks a lot of "smoothies", but her slurred speech and forgetfulness imply "smoothie" is just a term for alcohol to get past the radar.
* AlcoholicParent: While they couldn't state it outright (since ''Hey Arnold'' is still a kids' show, despite the myriad of adult themes), Miriam is obviously a heavy drinker, with the show using smoothies as a metaphor for booze. If you look closely when she grabs some ingredients for her "smoothies", she grabs a bottle of Tabasco sauce and if "The Patakis" was made, it is informed she would be attending AA.
* AllGirlsLikePonies: In "Road Trip," she reveals to Helga that when she was a kid, she wanted to learn to ride horses, but her dad refused to let her, fearing she'd get hurt. Her response to this, surprisingly enough, was to [[spoiler: become a champion mechanical bull-rider.]]
* BlindWithoutThem: Implied during the few times she loses her glasses or is shown without them.
* TheDitz: As a result of her drinking problem.
* DrivesLikeCrazy: Due to her drinking, Miriam has had her license revoked. When she took over for Bob's beeper store and drove Helga to school, all the kids were worried that Miriam was driving again (meaning that the kids know that Helga's mom is either a DrunkDriver or just a very, very bad one).
* HiddenDepths: She was once a world-class swimmer, won a bull-riding competition as a girl, and can run the family business better than Bob can if she wanted to.
* HypocriticalHumor: Calls Helga 'weird' in one episode when she hears Helga manically laughing in her StalkerShrine.
* INeedAFreakingDrink: She'll occasionally say that she needs a "smoothie".
%%* {{Meganekko}}
* MyGodWhatHaveIDone: In 'The Beeper Queen', when she realizes she's been neglecting Helga for her new job.
* OddFriendship: Develops one with Suzie in "Summer Love".
* VerbalTic: Often speaks in a slow, drawling voice. Justified as Craig Bartlett has revealed that Miriam is an alcoholic.

[[folder:Robert Simmons]]
-> Voiced by: Dan Butler

Fourth grade teacher at P.S. 118 starting in the second season, replacing the original LivingProp, Miss Slovak. Thinks of everyone and everything as "special".
* AdultsAreUseless: Specifically in the episode "Girl Trouble" when he doesn't punish Helga for bullying Arnold, yet he punishes ''Arnold'' for fighting back. Other examples include:
** "Buses, Bikes, and Subways"--doesn't double-check his head count and is totally oblivious to the fact that two of his students are missing until the bus is back home.
** "The Flood"--allows students to run riot for 3/4 of the episode and then tries to [[spoiler: climb up a ladder during the storm for help, and ends up falling into several feet of water, meaning the kids have to save his butt.]]
** "Aptitude Test"--mixes up two of the eponymous tests; doesn't bother to recheck the folders.
** "On the Lam"--doesn't know his science closet was raided until informed on the evening news.
* AmbiguouslyGay: Played by an openly gay actor, loves the theater, and has a very delicate, effete personality. In fact, a character who may or may not be his partner even appears in [[CrappyHolidays the Thanksgiving episode]].
** Confirmed by WordOfGay.
* CoolTeacher: He can be this when he's not being useless. In fact, his premiere episode, "New Teacher," was all about the kids realizing this after they gave him a hard time.
* ImagineSpot: In "Principal Simmons", Mr. Simmons imagines what the school would be like if he was the principal, which features the kids all beings friends with each other, Helga and Brainy walking together with their arms around each other, Wolfgang giving Eugene a piggyback ride, Harold becoming smart, the kids eating healthy food and happy to be the principal's helper.
* InkSuitActor: A very glaring example on a show with otherwise very outlandish character designs; Simmons strongly resembles his voice actor, Dan Butler.
* NiceGuy: One of the nicest adults in the series.
* NonStandardCharacterDesign: Considerably less cartoony-looking than the other characters due to being based on a real person.
* ObliviousToHisOwnDescription: He is the only one who doesn't recognize his own CatchPhrase in Helga's parody.
* OnlyOneName: It is strongly implied, but never explicitly stated, that his first name is Robert (in the Thanksgiving episode, he wrote a play that was based on his own life; we meet every character from the play in person later on except for him).
* WideEyedIdealist: His ImagineSpot is a good example of this.

[[folder:Alphonse Perrier du von Scheck]]
-> Voiced by: Paul Sorvino

The CEO of Future Tech Industries, Scheck is a greedy and heartless businessman who wants to tear down Arnold's neighborhood to build a gigantic, immaculate shopping mall. Only appears in TheMovie, where he is the BigBad.
* AffablyEvil: Appears to be this at first, but it fades over the course of the movie.
* BigBad: The main antagonist of the movie.
* BigNo: After he sees that [[spoiler: Arnold, Helga and Gerald have escaped - with the videotape that exposes him burning the document]].
* CorruptCorporateExecutive: Not only is he not above [[spoiler: burning a document declaring the neighborhood a national landmark]], the whole reason he wants to build the mall in the first place is to [[spoiler: get revenge after his family name was sullied over the "Tomato Incident" that happened in front of Sunset Arms]].
* EvilOverlooker: On the poster and DVD cover of TheMovie.
%%* GreenEyes
* KnightOfCerebus: He's much more evil and played seriously than the other characters.
* ManOfWealthAndTaste: A small running gag has Gerald voice admiration for Scheck's suit.
* SlasherSmile: Most notably when he's [[spoiler: burning the document declaring the neighborhood a national landmark]].
%%* SmugSnake
* SoftSpokenSadist: His voice is pretty unassuming and even somewhat soothing for a villain, but he tends to lose this when he gets mad.
* VillainousBreakdown: He starts out appearing as an affable but very weaselly businessman, but ends up as a raving madman who is [[MoralEventHorizon perfectly willing to]] [[spoiler: run over several people, including children, with his car.]]
%%* TheVonTropeFamily

-> Voiced by: Jennifer Jason Leigh

Only appearing in TheMovie, Bridget is a sort of spy girl/superheroine who helps Arnold and Gerald save the neighborhood by supplying them with equipment and [[spoiler:providing them a VCR to play the security tape exposing Scheck]].
* MsFanservice: Both Arnold and Gerald immediately fall for her as soon as they meet her, and Gerald even faints when she gives him a good luck kiss.
* PinkMeansFeminine: Her UtilityBelt that only comes in Black or Pink.
* TrueBlueFemininity: Her SpyCatsuit.

[[folder:Oskar Kokoshka]]
-> Voiced By: Steve Viksten

* AnnoyingLaugh: Eh heh heh heh!
* ButtMonkey: He largely deserves it, too.
* FunnyForeigner: Mentioned in one episode as hailing from the former Czechoslovakia.
* JerkWithAHeartOfGold: He's selfish, lazy, and leeches off his wife. However, in the episode where he's forced to look after Baby Oscar, whom he initially resents but grows protective over, and there are times he feels guilty about leeching off Suzie.
* LazyBum: When he finally does get a job delivering papers with Arnold's help, he's too lazy to even do that, making up excuses so that Arnold does it instead of him. It gets to the point that ''even [[NiceGuy Arnold]]'' calls him a "huge loser".
* LazyHusband: Lives off his wife ''and'' still expects her to do all the housework.
* ManChild: Lazy and childish, Oskar often neglects responsibility.
* NeverLearnedToRead: It's eventually revealed that he's illiterate. Arnold volunteers to teach him how to read.
* UglyGuyHotWife

[[folder:Suzie Kokoshka]]
-> Voiced By: Mary Scheer

* NoAccountingForTaste: Although she fights with Oskar often and has kicked him out on more than one occasion, she always seems to forgive him, only to have him make the same mistakes again.
* OddFriendship: With Miriam in "Summer Love".
* ParentingTheHusband: Often does this to Oskar as he leeches off of her and gambles often. Suzie is the sole source of income, and is run ragged by her childish husband.
* UglyGuyHotWife

[[folder:Ernie Potts]]
-> Voiced By: Dom Irrera

%%* BigOlUnibrow
* FieryRedhead: Male example, although he is mostly bald.
* FirstNameBasis: Unlike most of the other boarders, Arnold calls him Ernie in later seasons, although he does call him Mr. Potts early on.
* HotBlooded: He's very emotional.
* TheNapoleon: Shorter than Arnold, but very passionate about the demolition business.
* TinyGuyHugeGirl: He develops a crush on a very tall model named Lola, and the two even date [[spoiler:until they had a falling out due to Lola being uncomfortable with their difference in height, though she apologizes, and they remain friends at the end of the episode.]]

[[folder:Mr. Hyunh]]
-> Voiced By: Baoan Coleman, Music/RandyTravis (singing)

* CharacterizationMarchesOn: Mr. Hyunh is initially a stereotypical, high-tense Asian man who mostly panic and tends to yell the same thing over and over whenever there's trouble. Early into the show, this aspect of his character is lessened as they make him into more of a character and less of a stereotype.
* DaddyHadAGoodReasonForAbandoningYou: Gave up his then two-year-old daughter to soldiers who were airlifting civilians to safety during the VietnamWar, so that she would be safe and have a better life. The only reason he couldn't go with her was that the soldiers could only take one person with them.
* {{Determined Widow}}er: Back in Vietnam, he was raising Mai all by himself, his wife nowhere to be seen. (It's possible she fell victim to DeathByChildbirth, but this is never confirmed.) After he comes to America, he spends a good amount of time searching for his daughter.
* FunnyForeigner: In earlier episodes where he would shout the same word over and over.
* HiddenDepths:
** Though he comes off as a somewhat overdramatic FunnyForeigner in most episodes, some (in particular the ChristmasEpisode) where he has ADayInTheLimelight, show him to be more insecure and worried about his situation.
** There's also the episode where it's revealed he sings ''amazingly'' as a country artist. So much that Gerald was able to profit off of him for the episode before Hyunh chose "The Simple Things" of his life instead of the limelight.
* LargeHam: How he responds to frustrating situations.
--> '''Mr. Hyunh:''' This lint. ''Your lint''! I cannot keep cleaning up after you! I am ''not your mother''! ({{beat}}) ''I'm not his mother!''
** In "The Vacant Lot", he was this at the end, shouting "Play ball!" 10 times in a row.
-->'''Mr. Hyunh:''' Play ba-all! Play ball! Play ba-all! Play ball! Play ba-all! Play ball! Play ba-all! Play ba-all! Play ball! Play ba-all!
-->'''Grandpa Phil:''' WILL YOU BE ''[[PunctuatedForEmphasis QUIET?!]]''
** And the time he dressed up as Juliet in order to help Romeo Arnold learn his lines in "School Play".
* LastNameBasis: Even the ''adults'' at the Sunset Arms call him Mr. Hyunh.
* OnlyOneName: See LastNameBasis above.

[[folder:Miles and Stella [[spoiler:Shortman]]]]
->Voiced by: Craig Bartlett (show creator) and Antoinette Stella (an episode writer)

Arnold's long missing parents.
* AdventurerArchaeologist: Perhaps to make them not be exactly like Indiana Jones they aren't Archaeologists, but have other jobs that would mean they might spend most of their time in a South American rainforest. But they still manage to rescue an artifact from a Jungle Pirate anyway.
* BattleCouple: If Phil's stories and Miles' journal is to believed.
* BirdsOfAFeather: How they met. Miles overheard Stella talking about the clouds looking like ships.
* DaddyHadAGoodReasonForAbandoningYou: [[spoiler:They both left to help cure a deadly illness sweeping throughout the population of the South American country, particularly that of a secretive tribespeople who have helped them throughout the years who they owe their lives to.]] As Miles had written in his journal, they expected the trip to be a short one...
* HappilyMarried: They were very happy together.
* ParentalAbandonment: Both left Arnold to be looked after by his Grandparents to depart on an important mission.
* ScreamingBirth: To give Stella her dues she may have been angry at the time, but she manages to keep it together rather well for a woman [[spoiler:giving birth in remote Jungle Temple whilst a ''volcano is erupting all around her!'']]. Stella provides the picture for the page.
* WhipItGood: Miles is extremely proficient with a whip, using it to tether two cable-cars together at one point to stop one from falling.

[[folder:Principal Wartz]]
-> Voiced by: David Wohl

As you may have guessed, he's the principal of P.S. 118 and he's known to be harsh but has reasons to be. Throughout the show, Wartz often is seen taken punishments too far, even by following teachers but he has toned this down after realizing when he sees how the others handle order.
* DeanBitterman: One episode has Mr. Simmons call him out for being too strict of a principal. And another has him suspend Arnold for two days because he told him he was being too unfair to Harold.
* DisproportionateRetribution: In ''Suspended'' where Arnold begs him to let Harold back and Arnold just gets suspended.
* JerkWithAHeartOfGold: He’s harsh at times but he’s willing to negotiate if the situation can be resolved.
* LastNameBasis: His first name is never revealed.
* ManChild: Shown to be this as he is seen playing with toys at his work desk and sending fan mail to teen singing sensation, Ronnie Matthews.
* PetTheDog: He can be reasoned with, even letting a kid off the hook depending on the situation. He also has a set of toy animals on his desk in order to calm down and/or reduce the stress on any meeting he may have.
* ProperlyParanoid: Even if the kids have no interest in misbehaving, Wartz is often like this.
* SternTeacher: As a DeanBitterman like principal.

[[folder:Willie the Jolly Olly Man]]
-> Voiced by: Dan Castellaneta

A mean, sadistic, downright crazy guy who works as an ice cream man.
* AesopAmnesia: Subverted. In ''Career Day'', Arnold teaches him how to properly do his job and avoid getting fired. In subsequent appearances he flip-flops from being the same jerkass he always was, and actually doing his job well.
** When Grandpa Phil accidentally runs him off the road in ''Grandpa's Packard'', he goes as far as to dress up in drag, and trick Phil into giving his address, so he can steal the Packard from him. He apologizes after he gets arrested, though.
** He makes a small appearance in the movie, though, where he seems to be good at his job again.
* AmbiguouslyBrown: Has tan skin.
* CharacterizationMarchesOn: He didn't start out crazy.
* {{CloudCuckooLander}}: He's apparently convinced in ''Grandpa's Packard'' that the start of his bad day was his dog laughing at him.
%%* EvilLaugh
* FreudianExcuse: In 'Career Day', Arnold finds out he's been fired from every single job he's had, and his BadBoss is none other than his ''own Dad'', who treats him with utter contempt.
* IronicNickname: The ''Jolly'' Olly Man.
* JerkAss: He'll drive off without giving kids their ice cream, not give them the right flavors, yell at them and treat them with no respect, or just outright ignore them.
* NiceHat: Mandatory because of his job.
* NoSocialSkills: He was not aware there was ''anything'' wrong with his attitude, and views the children he serves as frightening. When his boss/father shows up saying that his numbers are down, he says it's not his fault that kids these days don't want ice cream. There was also a moment in ''Grandpa's Packard'' where he says that he was having a terrible day, one of the reasons being that the expiration date on his milk was wrong. ''He's'' not wrong, ''the milk'' was wrong. It'd be somewhat believable if it wasn't preceded by his dog laughing at him, and followed by a maniacal Grandpa Phil running him off the road on purpose.
* PetTheDog: He gives Arnold an 'A' at the end of 'Career Day' and a free ice-cream, as thanks.
* SlasherSmile: Accidentally scares kids off with his smile when Arnold is trying to improve him.
* ThroughTheEyesOfMadness: We occasionally see how he views the world. In ''Career Day'', he sees the city in black and white and nothing but slums, the kids as hyperactive [[CreepyChild creepy children]], and his ice cream truck as a cage.
** ''Grandpa's Packard'' shows that he views Grandpa's running him off the road as a malicious act against him, and not a mistake, complete with an evil looking Packard spewing flames and Grandpa Phil laughing maniacally.

[[folder:Vincent the Pigeon Man]]
-> Voiced by: [[http://en.wikipedia.org/wiki/Vincent_Schiavelli Vincent Schiavelli]]

An outcast who lives atop an abandoned apartment block who prefers to be around pigeons more than humans.
* ButNowIMustGo: In the ending, he leaves the city to live with his feather friends.
* LonersAreFreaks: He lives alone with only pigeons by his side.
* MisunderstoodLonerWithAHeartOfGold: Some of the kids think he's some kind of bird-obsessed freak, when he's just a friendly old guy who's just really fascinated with birds.
* NotGoodWithPeople: He understands birds, just not people.
* OnlyKnownByTheirNickname: Everyone that knows him calls him Pigeon Man.

[[folder:Mr. Marty Green]]
-> Voiced by: James Keane

A local butcher that runs for councilman in ''Mr. Green Runs''.
* BerserkButton: NEVER throw a board over a pothole and say it's fixed, especially after he's called you countless times requesting to get it fixed.
* BewareTheNiceOnes: If Councilman Gladhand had bothered to actually fix the pot hole; he'd probably still have a job.
* DefrostingIceKing: When Harold steals a ham from his shop, Mr. Green punishes him by forcing him to work for free for a week. Harold grows to like the job, though Mr. Green sees him as trouble. Then at the end, Mr. Green warms up to him when he offers to help out during a busy hour.
* {{Expy}}: Of the title character from the movie, Film/{{Marty}}.
* LargeHam: When Arnold is looking for a musical act for a dance, Mr. Green offers his singing voice which really stands out to say the least.

[[folder:Coach Jack Wittenburg]]
-> Voiced by: James Belushi

A local coach who's forgetful in names and only has limited experience, often needing Arnold to help him out.
* DisproportionateRetribution: During a basketball game, he tells the kids that they have to pass the ball to his son Tucker so he can score. When Arnold ignores his advice, explaining that he wasn't open and had to make the shot himself, Coach Wittenburg benches him for the rest of the season.
* DrillSergeantNasty: His method of coaching involves screaming at the players, until Arnold comes in.
* AFatherToHisMen: He does care about the kids he's coaching as he really wants them to succeed. And when he tries to organize a Synchronized Swimming Team, he goes to Arnold and friends, knowing they've been there for him in the past.
* HotBlooded: His competitiveness with his wife, Tish can get pretty out of control sometimes.
* LargeHam: Much like your typical super-competitive coach.
* {{Malaproper}}: Constantly speaks in this manner as he often has no idea what the stuff he talks about means.
* TheNicknamer: To the kids, he constantly calls Arnold, Arnie.

!!Other Kids

-> Voiced by: Grant Hoover

A cousin of Arnold's who is disconcertingly similar, but much stranger and less attractive. Naturally, Lila falls head over heels for him.
* AmbiguousDisorder: Arnie displays several signs of ASD, particularly AspergersSyndrome, such as odd hobbies (counting things, reading ingredient labels [along with seemingly knowing what they are and how to pronounce them]) and collections (specifically balls of lint and "plain flavored" gum), displays muted outward signs of emotion, and seems to have difficulty in social interaction. These traits lead some of the other characters to think he is "dull" and "slow."
* BizarroUniverse: The episode "Arnold Visits Arnie", in which just about all of the side character kids and main cast members get an eerily similar doppelganger with a completely opposite personality.
* {{Cloudcuckoolander}}: His hobbies include collecting lint and reading the ingredients off of packaged products.
* CountryCousin: He lives in the country in contrast to his city cousin.
* CreepyChild: Not as much as Curly but his [[{{Cloudcuckoolander}} bizarre personality]] makes him rather weird to most people.
* CreepyMonotone: Though the "creepy" is entirely up to the viewer's discretion.
* JokeCharacter: Reportedly a character created as an in-joke response to OffModel animation.
* KavorkaMan: Big time. He isn't that good looking yet Lila would rather be with him than Arnold.
* MirrorUniverse: In "Arnold Visits Arnie", to some degree. That is, of course, if you [[spoiler: believe that it isn't normal for Arnie to go AxeCrazy on his cousin and/or]] want to include the character alignments of the citizens of Arnie's hometown.
* MurderTheHypotenuse: [[spoiler: In "Arnold Visits Arnie" towards the end of the episode. It turns out it was just a dream, though.]]
* NightmareFace: [[spoiler: Arnie gets one, also a result of the fiendish dream. Almost makes you wonder about Arnold a little...]]
* OddballDoppelganger: To Arnold.
* UglyGuyHotWife: Arnie's less-than-attractive guy to Lila's, and later Lulu's [[spoiler: (though this turned out to be AllJustADream)]] rather pretty girl.

[[folder:Rex Smythe-Higgins III]]
-> Voiced by: Joey Stinson

Rex Smythe-Higgins III is the grandson of Grandpa Phil’s rival Rex Smythe-Higgins I and is the same age as Arnold. He’s often had to complete against Arnold and is a Polishing school alumni.
* JerkWithAHeartOfGold: He may be arrogant at times, but he doesn’t like cheaters and would rather play fair in completion, "Tour de Pond". In "The Pig War", he helps Arnold save Abner from being cooked by the British Pig War team after learning that he's Arnold's pet.
* TheRival: To Arnold in a few episodes.
* WiseBeyondTheirYears: He’s actually much more mature than his grandpa considering he’s still a kid.

-> Voiced by: Toran Caudell

The leader of the fifth graders and bullies the fourth graders around.
* TheBully: Much worse than Harold and Helga.
* GeniusBruiser: He's surprisingly crafty, from devising plans for Trash Can Day to making sure Chocolate Boy doesn't eat chocolate for a month.
* HiddenDepths: He mentions that he needs to take oboe lessons until four.
%%* JerkAss
* JerkJock: Shows shades of being an unpleasant jock, especially "Longest Monday".
* KarmaHoudini: Most of the time, he and his fifth graders succeed without punishment.
* NotSoAboveItAll: He's very superstitious.
* TheRival: Acts this way towards Arnold and the other fourth graders.
* YoungerThanTheyLook: It's hard to imagine that he's only fifth grade considering he has an appearance and a voice of a high school student.

-> Voiced by: Phillip Van Dyke

Another bully introduced in 'New Bully on the Block', explaining he was at Juvenile prison and only recently got out.
%%* BigOlUnibrow
* TheBully: Like Wolfgang, Ludwig is a bully who picks on the fourth graders.
** Furthermore, "New Bully on the Block" was written for the express purpose of having all three Arnold's in a single episode.
* ChuckCunninghamSyndrome: Never appears again after "New Bully on the Block", possibly due to the poor reception the said episode received.
* KarmaHoudini: Like Wolfgang, he gets away with bullying the fourth graders.
* OnlyOneName: And he's named after a famous musician just like Wolfgang.
* RealMenWearPink: He tells Arnold he has to go to his tap-dancing class when Arnold tries to arrange a meeting between him and Ludwig.
* RememberTheNewGuy: Averted- Arnold ''vaguely'' remembers Ludwig, but the show acknowledges he's never been seen before by explaining he went to Juvie before the series began.
* WeHardlyKnewYe: Goes right in hand with OneShotCharacter.

[[folder:Chocolate Boy]]
-> Voiced by: Jordan Warkol

A young boy with an [[GRatedDrug unhealthy obsession with chocolate]].
* BigEater: Of anything chocolate. [[spoiler: But now he's obsessed with radishes.]]
* GRatedDrug: He's obsessed with chocolate like a crack addict. [[spoiler: Until the end where he gets addicted to radishes.]]
* HiddenDepths:
** In his spotlight episode, he reveals the reason he's so addicted to chocolate is because [[spoiler: he misses his nanny. His parents told him chocolate was bad for him, but his nanny secretly gave him some until she had to leave.]]
** Plus in ''Oskar Can't Read?'' he's shown to be able to read through an excerpt of Literature/ATaleOfTwoCities with no trouble, even for someone seemingly in kindergarten.
* OnlyKnownByTheirNickname: Everyone calls him Chocolate Boy, and his real name is never revealed.
* SeriousBusiness: His obsession with chocolate is so bad that it makes him do stupid things just to get some. He once went two weeks without eating any chocolate so he could win a ten-pound bag of the stuff. And he eats it all in one sitting. And in ''Buses, Bikes, and Subways'' he sneaks onto a field trip to the chocolate factory.
* ThePigPen: Often has chocolate stains all over him.
* TrademarkFavoriteFood: '''Chocolate.''' [[spoiler: Now it's radishes.]]