!!The Main Trio

->Voiced by: Greg Eagles

The GrimReaper who is fated to be Billy and Mandy's "best friend" forever after losing a limbo contest to them.
* AbusiveParents: Depending on the episode. His mom always complains about his lack of enthusiasm for his job and his dad would never talk to him and always listened to country music.
* AcquaintedWithEmergencyServices: He has this relationship with the nursing staffs at the retirement homes when he comes for the elderly residents, as shown in Season 5 "Home of the Ancients".
-->'''Gloria''': Hi, Grim.\\
'''Grim''': S'up, Gloria.\\
'''Gloria''': Aw. Are you here for Mr. Silverman?\\
'''Grim''': No. That's next week.
* {{Adorkable}}: Despite being the shadow of death itself, he has his fair share of adorably dorky moments throughout the series, especially during the flashback in ''Wrath of the Spider Queen''.
* AffablyEvil: Is remarkably polite when he isn't putting his scythe to work or getting bossed around by the title characters.
* TheAgeless: ExactlyWhatItSaysOnTheTin.
* AndIMustScream: Eternally a prisoner to Billy and Mandy. Can't violate his contract with them or else he'd ''then'' spend an eternity in the Underworld Prison.
* AntiHero: He's this only when a greater evil threatens the world or Billy and Mandy.
* AntiVillain: He's not TheGrimReaper by choice, but because he was forced by his parents to be (though this does flip-flop around. One special revealed being a Reaper was being voted by your fellow students in ''high school''). He's also constantly getting his weight thrown around by Billy and Mandy. In fact, if he didn't suffer these two circumstances, he wouldn't be villainous at all. That's proven, as he's a fairly nice guy, whenever he's not on his job to take someone's life.
* BadassBoast:
** "You don't know who you're messing with, man! I am TheGrimReaper!"
** He had another good one in "Grim vs. Mom".
-->'''Grim:''' Foolish mortal! I don't think you know who I am. Let me give you a hint! (''Magics up his scythe'')
* BadassLongcoat: As expected of the Grim Reaper.
* BadlyBatteredBabysitter: His general function in the show.
* BewareTheNiceOnes: He's pretty nice when not reaping, though it has been made clear on several occasions that despite his attitude and butt monkey status to Billy and Mandy, he is not one to be trifled with when his patience is at an end. Just ask Jack O' Lantern.
* ButtMonkey: A lot less than Billy, but he has his moments when he's near Mandy or a rival.
* CantStandThemCantLiveWithoutThem: On several occasions when he is given the opportunity to be free of Billy and Mandy.
* ConditionedToAcceptHorror: In ''Big Boogey Adventure'', he's able to get Horror's Hand, which requires someone to face their worst fears, because his worst fear is [[WithFriendsLikeThese having to spend time with Billy and Mandy]], which he has to do every day anyway.
* CrouchingMoronHiddenBadass: While being pushed around by Billy and Mandy, he still knows how to get the job done as the reaper and kick a mean can of ass. He can be legitimately frightening when he wants to be.
* DarkIsNotEvil: At the very least nowhere as evil as [[VillainProtagonist Mandy]].
* DeadpanSnarker: He makes a lot of death jokes and underworld puns.
* DemBones: Grim is like this under his robes. More than once, the other two protagonists have been known to take him apart in order to carry him in a backpack or other small container.
* TheDevilIsALoser: He's portrayed as an unpopular sissy even before he becomes the kids' servant. In his past, it is shown he didn't even ''want'' to be the Grim Reaper, it was just something his parents forced him to do. He took up his role in full swing in order to terrify and get revenge on those who bullied him at school.
* DoesNotLikeShoes
* DontFearTheReaper: Downplayed; he's an AffablyEvil PunchClockVillain who can be scary when he's ''reaping'' somebody but is otherwise a nice guy.
* EvilHasABadSenseOfHumor: Even Mandy is sometimes taken aback by the macabre horror Grim finds delightful.
* FourTemperamentEnsemble: The Melancholic
* GrumpyBear: Downplayed. He's only grumpy when he's in a bad mood. Mandy, on the other hand.
* GlowingEyesOfDoom: Several times when he gets absolutely enraged.
* TheGrimReaper: Obviously.
* HeroicComedicSociopath: Death amuses him, like when he laughs during a show when a patient flatlines, something that even Mandy looked sad to see.
* HeelFaceTurn: After making the deal with Billy & Mandy.
* HotBlooded: Pretty often, actually.
* HumanityEnsues: In "Night of the Living Grim". He gets better, though.
* HypercompetentSidekick: This the reason why Mandy wants to keep him and ditch Billy.
* HypocriticalHeartwarming: Quite a few times when it comes to Billy and Mandy. One of the best examples was in "Scythe 2.0":
--> '''Grim:''' You keep away from those kids! If ''anyone'' is going to have their heads, it's going to be ''me''!
* IAmBigBoned: A variation in the comics. Grim isn't thin. He's "delicately boned".
* ICallItVera: In "The Taking Tree", we learn that he calls his scythe "Jodie".
* KissedKeepsake: After Eris is tricked into kissing Grim, he says he never washed his face before and won't start doing it now.
* TheKirk: More or less trying to survive being stuck with two insufferable children.
* MistakenForPedophile: Heavily implied in "Duck!", where he gets arrested for removing his cloak in front of children while shouting "Look at my body!" in an attempt to explain to the children that he is incapable of passing gas.
* MultipleChoicePast: His many flashbacks to his past seem pretty unreliable. Possibly parodied at one point as well--two of his proposed backstories ''directly contradict each other'' in such a way that would be impossible to HandWave, {{Retcon}} or even ignore outright[[note]]in one, he wanted to be a singer but his dad wanted him to be the Grim Reaper, while in the other his dad wanted him to sing while he wanted to become the Grim Reaper[[/note]].
* NoRespectGuy: Even in the underworld, he gets no respect for his many duties as Reaper.
* NotSoAboveItAll: He tends to get swept up in Billy and Mandy's antics pretty regularly.
* OddFriendship:
** He actually manages to bond with Billy quite a bit.
** He and Mandy share a dark and macabre sense of humor, helping them to get along at times.
* OnlySaneMan Despite being an all-powerful supernatural being hanging around a suburban neighborhood, he is much more grounded and stable than every other character.
* ParentalSubstitute: For Billy. Both of his parents are alive, but his dad is an idiot and his mom is a psychopath, so Billy respects and admires Grim much more than either of them. He cooks and cleans for him and is quite fussy about him doing his homework, but also provides an actually respectful adult male figure in his life. Billy even says in one episode that Grim is his idol, and Grim in turn occasionally displays outright fatherly affection for him.
* PhysicalGod: He's the Grim Reaper, after all.
* PunchClockVillain: As he himself once stated, he's just doing his job. He's also very friendly when not doing so. After all he is not the cause of the death merely the aftereffects.
* RageBreakingPoint: Normally subservient and kind even when being bossed around, he ''does'' have limits though; when he's finally had enough and loses it, even Mandy herself often won't mess with him.
* RealityWarper: With his scythe.
* ReallySevenHundredYearsOld: He was a little kid during the Stone Age.
* RedAndBlackAndEvilAllOver: His BlackCloak is red on the inside.
* ScaryBlackMan: His voice actor is black.
* ScreamsLikeALittleGirl: Depends on the episode
* ShipperOnDeck: He teasingly ships Billy and Mandy occasionally.
* SinisterScythe: Which can do just about anything...except whack the weeds in Skarr's garden.
* SociopathicHero: He dosen't like conversing with humans, much less saving them.
* TragicVillain: PlayedForLaughs. He didn't become TheGrimReaper by choice, but because his parents wanted him to... [[MultipleChoicePast sometimes]]. Afterwards, he became a PersonOfMassDestruction. He also softens after the deal with Billy and Mandy.
* TallDarkAndSnarky: He is ExactlyWhatItSaysOnTheTin.
* TooDumbToLive: If he never wagered his own freedom, he wouldn't have to put up with Billy and Mandy. The only thing he would've lost would've been an opportunity to collect a hamster's soul.
* UnexplainedAccent: Grim's Jamaican accent. His grandmother also has one, and has a Jamaican look to her to boot.
* VillainProtagonist: A surprisingly downplayed example, since he shows his evil side sporadically and often (but not always) after being provoked.
* VillainsOutShopping: Whenever he isn't ordered to kill someone, he lives a perfectly normal life.
* WellDoneSonGuy: While his backstory is a bit fluid, "Dad Day Afternoon" presents him as this, desperate to earn the approval of a father who loved country rock music more than him.
* WillfullyWeak: Deliberately avoids abusing his powers to prevent causing problems. Unfortunately for him, that's exactly what Billy and Mandy end up doing.
* WouldHurtAChild: He's been shown planning ways of escaping his deal with Billy and Mandy, typically by killing them in unusual ways.

->Voiced by: Creator/RichardStevenHorvitz

A dim-witted boy who frequently causes problems due to his idiocy. Nonetheless, he's usually the most innocent and happy-go-lucky of the trio.
* {{Abusive Parent|s}}: To his "son", the giant spider, Jeff. (Semi-justified in that Billy is extremely stupid and has an irrational fear of spiders) Billy tries his best to squish Jeff including sending an exterminator to crush him beneath a huge cowboy boot, throwing furniture onto him, and [[CrossesTheLineTwice cutting the brake cables in his car]].
* AcquaintedWithEmergencyServices: In Season 2 "Educating Grim", when Billy tries to race Grim and Mandy to school, he immediately runs into the school's front sign. Cue Nurse Penbroke walking outside hold first-aid kits looking annoyed. After Billy and Mandy leave school, Billy is already covered in bandages and walking with a crutch. When Nurse Penbroke [[StepfordSmiler happily]] waits outside for Billy, he tells her he's done for today and then she releases an exhausted sigh.
-->'''Nurse Penbroke''': Oh, Billy.\\
'''Billy''': ''(cheerfully)'' Hi, Nurse Penbroke. I can't feel my legs.
* {{Adorkable}}: He's so dumb and stupid it's adorable.
* AllLovingHero: Unless you're a spider or a clown, in which case [[CrossTheLineTwice he'll try to murder you]], Billy is surprisingly adept at befriending pretty much everybody, and has succeeded in ending conflicts nonviolently several times.
* AmbiguousDisorder: It's fairly obvious that Billy has genuine mental problems in addition to being extremely stupid, as shown by his bouts of psychotic, murderous rage. He may have inherited this from his mother.
* AmbiguouslyJewish: His family apparently celebrates Hanukkah in addition to Christmas, though the way he says it makes it sound like an excuse to get more presents.
* AnnoyingLaugh: And how!
* ArsonMurderAndJaywalking: Billy's three greatest fears are spiders, clowns, and the mailman, with the greatest fear of them all being a spider/clown/mailman hybrid.
* AsskickingEqualsAuthority: In ''A Kick in the Asgard'', he was such a good fighter that even the likes of Thor and Odin feared him, and is revealed to have became the ruler of Asgard in TheStinger of the episode.
* AxCrazy: The disorder thing? Well it can get pretty severe for a clown or a spider (for daring to be different) or for everyone if Billy is in a destructive and hyperactive mood (which he pretty much is all the time) and wields a hammer.
* BewareTheSillyOnes: Billy is often the dumbest character on the show, but he has been shown to have bouts of psychotic rage that manage to scare even Mandy.
* BlackBeadEyes: One of the few characters on the show who has this eye style.
* BrattyHalfPint: He can sometimes become one.
* BumblingSidekick: While he has moments of surprising insight or competence, he generally functions as this to either Grim or Mandy.
* ButtMonkey: He gets a lot of physical abuse.
* ChaoticStupid: When Billy takes Mandy's raw nerve, he gleefully abuses Grim, implying that a lack of courage was the only thing that stopped him from doing so before (unless the nerve also influenced his overall disposition since it was ''Mandy's''). He also has an "inner frat boy" that advises him to beat the crap out of anything he doesn't understand.
* CheerfulChild: He rarely has outbursts of rage, but when he does, this goes away really fast.
* ChildhoodFriends: He's known Mandy since they were toddlers.
* CloudCuckooLander: He will spout stuff that makes no sense except to him and maybe Irwin
* CordonBleughChef: In an early episode he dreamt that he made cookie dough out of assorted junk food, then ate it raw because [[NoodleIncident he wasn't allowed to use the oven anymore]]. He also apparently eats his cereal with chili and makes his waffles with pickles. One episode has him simply put a ''live turtle'' between two pieces of bread and proudly proclaim "Now that's what I call a sandwich!".
* CrouchingMoronHiddenBadass:
** He was able to take on an entire alien fleet by himself, and even [[PhysicalGod Grim]] and [[TinyTyrannicalGirl Mandy]] run from him in fear when he's angry. He's a moron, but he's also very competent badass when he wants to be.
** In "Secret Snake Club", he actually becomes a CIA agent, tracking down a fugitive and exposing [[spoiler: Irwin's plans with the macrame club]].
** He singlehandidly defeated all of Asgard, Odin and the rest of the pantheon included, and he did it with a smile on his face the entire time.
** He also helped Hoss Delgado fight a group of zombies with nothing but a stick.
* TheDitz: His IQ is [[ExaggeratedTrope -5]], being outperformed in the test by a shovel and two candy bracelets (they got a positive 17).
* DropTheHammer: His WeaponOfChoice is a war hammer, which he is surprisingly skilled at wielding.
* DumbassHasAPoint: Very commonly chimes in to point out the flawed logic in Mandy or Grim's thinking, only to be dismissed as an idiot.
* DumbIsGood: Played with. While his idiocy gives him a childish innocence that allows him to befriend even the most horrible monsters and act unambiguously heroic much more frequently than the other two, [[ChaoticStupid his complete lack of self control and extremely destructive tendencies]] lead him to be arguably the ''most'' dangerous of the three.
* EveryoneHasStandards: Even he thinks Fred Fredburger is annoying.
* ExtremeOmnivore: He enjoys eating boogers, toenail clippings, and (it's heavily implied) cat and dog poo, the last of which he actually uses as steak sauce.
* FieryRedhead: Only when he's angry.
* FluffyTamer: His specialty is befriending supernatural horrors that help the trio out in a pinch.
* FourTemperamentEnsemble: The Sanguine
* FriendToAllLivingThings: Although in the case of spiders, he doesn't love them back.
* FutureBadass: In the Big Boogey Adventure. Most notably, in the five minutes of screentime he gets, he almost never says or does a single dumb thing. In fact, he somehow managed to time travel back in time without the use of a nearby inoperable Time Gate. And this is [[TheDitz Billy]] we're talking about. It makes one wonder what did Mandy do to make Billy become this way...
* GagNose: Has a bulbous pink nose that is often bruised or even knocked off his face.
* {{Gasshole}}. Lampshaded by his mom, his first words were in fact gas attacks.
* HeManWomanHater: He insists that Mandy and other girls not be allowed on his baseball team... despite them soundly being better at it than he is. Even having Mindy outperform his team didn't change Billy's mind.
** Leading to Mandy and Grim discussing whether they should hang lampshade or not. They decide [[TheDitz Billy]] is not worth that trouble.
* HiddenDepths:
** He is shown to dance well, defeat multiple enemies in combat - sometimes without even touching them - and is prone to simple-minded wisdom that actually make a whole lot of sense.
** He's also occasionally surprisingly eloquent for an idiot.
* IdiotHero: Far more traditionally heroic than [[TokenEvilTeammate Mandy]] and [[AffablyEvil Grim]], but also much more idiotic and twice as destructive.
* ImprobablyLowIQ: -5. Again, a shovel and two candy bracelets are smarter than he is.
* InformedJudaism: The Christmas episode states he's Jewish, but it's never brought up again.
* InnocentlyInsensitive: Whenever he insults Grim, it's mostly when he's acting as Mandy's parrot. On his own, he usually speaks highly of Grim, but also acts like a spoiled and bratty kid.
* IronButtmonkey: To the point that he could be considered TheChewToy of the show.
* JerkassBall: As with Mandy, Billy has his moments too.
* JerkassHasAPoint: In "Wrath of the Spider Queen" Billy delivers a massive KickTheDog speech to Jeff where he tries to convey just how much he hates the spider. It was incredibly excessive compared to what triggered it but Billy did raise the point that somehow Jeff ''still'' hadn't figured out the depths of just how much Billy hates spiders.
* {{Keet}}
* KindheartedSimpleton: Downplayed, while he causes a lot of trouble, it's more out of his stupidity rather than malice. He generally comes off as well-intentioned and kind.
* LackOfEmpathy: Especially apparent when interacting with his "son", Jeff.
* LethallyStupid: ''Everything'' Billy does within the show will inevitably result in mass destruction and chaos, especially when magical artifacts like Grim's scythe are involved.
* LikeParentLikeChild: He's both stupid (like his father) and mentally unstable (like his mother).
* MadeOfIron: He has suffered many injuries throughout the show's run (several of which result in his skin being torn open) and absolutely none of them were permanent. A few of his injuries involve ''having his entire face being blown or torn off''!
* MajorInjuryUnderreaction: Most of the amusing injuries he sustains, he makes little to no reaction to any of them, which isn't really much of a surprise since he's probably too stupid to realize he got injured.
* MeaningfulName: His name means "desire".
* TheMentallyDisturbed: He does the unusual combo of being both moronic and completely insane.
* MoralityPet:
** For [[AntiHero Mandy]]. When she's not bullying him or helping him for her own personal gain, she's treats him as a scolding mother would treat her son.
** He's also one to [[SociopathicHero Grim]], who seems almost affectionate towards him at times.
** He's one to [[spoiler: [[AntiVillain Mrs. Claus]] in the ChristmasEpisode, after apparently being the only person in centuries to offer her any help with her multiple duties at the North Pole (without messing up). In fact, Billy's the one who stops her from taking over the world by appealing to her humanity, and by turning Santa back to normal and getting him to apologize for dumping all the work on her.]]
* TheMcCoy: Stupid and impulsive.
* ObliviouslyEvil: Sure he "abuses" his "son" Jeff despite the latter's attempts to flatter him, but that's only because Billy has irrational and psychotic arachnophobia. ''Underfist'' reveals that this was the result of [[spoiler: the true antagonist dangling spiders in front of Billy when Bill was a baby ForTheEvulz]].
* OddFriendship: His two closest friends are an obscenely dark and anarchistic girl and the humanoid personification of death.
* OneManArmy: He's occasionally shown to be almost disturbingly powerful when angry, to the point where even Mandy is terrified of him.
* OnlyFriend: He appears to be the only person Mandy actively hangs out with.
* PinkGirlBlueBoy: The blue boy to Mandy's pink girl.
* ThePollyanna: One episode has Billy chronicle his daily experience. It's surprisingly depressing. Not that he notices. His life is honestly pretty horrible, but he remains a blissfully oblivious idiot regardless.
* RapidFireYes: He would often respond with "yeahyeahyeahyeah..." when he's excited.
* RedOniBlueOni: The red to Mandy's blue.
* ScreamsLikeALittleGirl
* ShesNotMyGirlfriend: Says this word by word when Grim assumed such about him and Mandy in the second episode.
* SimplemindedWisdom: He does this more often than he should, making you second guess his stupidity.
* SmarterThanYouLook: Make no mistake Billy is genuinely as stupid as he comes across but he's typically more tuned in to things than he appears.
* StrongFamilyResemblance: To his dad.
* TokenGoodTeammate: Compared to Grim and Mandy at least which admittedly doesn't say much.
* TookALevelInDumbass: By the end of the show, Billy's become an Epic-Level dumbass.
* UnstoppableRage: When he's in this mode, even ''Mandy'' is scared of him. He more or less becomes the most powerful character on the show when in this state, as he always curbstomps his opponent.
* VillainProtagonist: The mildest example of the three, though it must be said that he can be as horrible as Mandy towards Grim and the whole world though in a mindless way. He usually gets a pass due to being mentally stunted and can be harmless when he isn't actively AxCrazy. He's also the only one of the three who ever has heroic motivations, though he tends to do more harm than good when acting on them.
* WhyDidItHaveToBeSnakes: Hates spiders with a passion, which creates some rift between him and his spider-baby Jeff.

->Voiced by: GreyDeLisle

The polar opposite of Billy; a merciless, cynical and manipulative little girl who frequently abuses Grim's power to get what she wants. She almost never smiles and terrifies almost everyone around her, her parents included. Unlike Billy, she's stable, sane and intelligent.
* TheAce: She's hypercompetent at pretty much everything and has almost the entire universe grovelling at her feet. It makes her plans for world domination all the more terrifying due to how ''plausible'' they are.
* ActionGirl: She's the most consistently competent in a fight out of the three of them.
* AllGirlsWantBadBoys: She falls in LoveAtFirstSight with a goth artist boy who Billy befriends in one episode. Her reaction is surprisingly adorable. The revelation that he's a poser makes her immediately lose interest in him.
* AmoralAttorney: Her Halloween costume in one episode.
* AnimeHair: Her hair sticks up at the back and curls a little, resembling devil horns.
* AntiHero: Either a NominalHero or a VillainProtagonist.
* ArbitrarySkepticism: Despite living in a world where supernatural elements are commonplace, and being friends with the Grim Reaper himself, Mandy adamantly refuses to believe in such things as Santa Claus and the Tooth Fairy.
* BadassNormal: Despite not having any powers, her intimidation towards others gets the job done.
* BewareTheQuietOnes
* BigDamnHeroes: Despite her goal on world domination, she saved the world multiple times.
* BigBad: Of The Grim Adventures Of The Kids Next Door.
* BigOlEyebrows: Has two big ones that cover her entire face.
* BrightIsNotGood: She may be the inverted version of a PerkyGoth. She wears brightly-colored clothes and has a Gothic personality.
* CardCarryingVillain: She makes no excuse for her being evil, and absolutely ''refuses'' not to be seen as anything but.
* TheComicallySerious: She's always overly serious, but is so, in a slapstick and humourous manner.
* CreepyChild: She tricked The Grim Reaper into eternal servitude, using him as her maid and his powers for personal gain, and faces down everything from the Boogeyman to Cthulhu with nothing more than a wry comment. She also never smiles, ever, because doing so would cause the universe to implode. She was also able to take over a large evil brain/alien when it ate her brain.
* DeadpanSnarker: Definitely.
* DeathGlare: In which intimidates anyone.
* TheDreaded: Almost ''everyone'' get scared of her just by using her words, and she has already taken over the world because everyone fears her. This goes even to the point where ''Grim'' of all people has nightmares of her.
* EmotionlessGirl: She seems to have only three major emotions: Indifference, disgust, and anger. This trope was exaggerated over time thanks to Flanderization. In season 1, she spoke with more emotion in her voice and was far more prone to looking surprised or worried at the strange things she came across. She also ''smiled'' at the end of the first episode and the universe didn't fall apart.
* EnfantTerrible: Young enough and psychopathic enough to qualify.
* EvenEvilHasStandards: She wants to rule the world and [[DystopiaJustifiesTheMeans turn it into a dystopia]], but she is not okay with cheating.
* EvenEvilHasLovedOnes: She does care about Grim and Billy, and once fell in love with a gothic guy (though she wasn't proud of it). She does seem to have a somewhat normal relationship with her parents (even straining herself to tell her dad she loves him for Father's Day while also giving him Grim's services for the day.) While she also does push them around somewhat, she is shown to be very surprised when her parents admit that they're sort of scared of her.
* EvilGenius: She's able to manipulate almost every villain and monster for her own will, and God help you if you dare try to cross her.
* EvilHero: PlayedStraight.
* {{Flanderization}}:
** From simply an apathetic, snarky kid with a HairTriggerTemper and a bossy streak to an [[EmotionlessGirl emotionless]], evil, and totally sadistic psychopath trying to take over the world.
** Her competence was wildly amplified; she went from a smart little girl who could think quick in a pinch to an EvilGenius who not only can pretty much fix or undo anything by just appearing on the scene, but owns everyone apparently.
* FourTemperamentEnsemble: The Choleric
* FlatEarthAtheist: She is rendered immune to the Tooth Fairy's powers by revealing, to his face, that she doesn't believe in him.
* FluffyTheTerrible: She's a tiny little girl in black Mary Jane's who almost always have blonde hair shaped like devil horns and wears pink outfits with flowers on them. She's also the scariest being in the universe.
* GaggingOnYourWords: As revealed in "Sickly Sweet," Mandy is such a {{Jerkass}} that even something as simple as saying "please" is nearly impossible for her.
* {{Goth}}: General consensus is that she's pretty much a Lone Psycho Goth, albeit one that dresses in an ironic fashion.
* GothGirlsKnowMagic: PlayedWith. In contrast to her appearance she has a cynical and dark personality befitting a {{Goth}}, and does not have any inherent magic, but sporadically gains temporary supernatural and magical powers in episodes.
* GreaterScopeVillain: She's never the main villain barring the KND crossover, but she is responsible for enslaving Grim, leading to pretty much all of the supernatural occurrences in Endsville. And while she always stops them, it is explicitly because she plans on conquering the world herself, which she is shown to have done in the BadFuture.
* GuileHeroine: She can take down foes both mortal and immortal in seconds.
* HairDecorations: Wears a black headband.
* HatesBeingTouched: Do not touch her unless you wish to be bitten or punched.
* HiddenDepths:
** The prospect of living a life of quiet desperation is ''the only thing'' that can shake Mandy to her core.
** She seems to actually care for Grim and Billy, as seen in "Big Boogie Adventure" when it seems that Billy may actually have been killed by the Kraken.
* HijackingCthulhu:
** In a certain episode, a [[BrainFood brain-eating]] [[EldritchAbomination alien monster]] with a [[Music/{{Voltaire}} familiar singing voice]] has been spending the whole episode being fed by Billy. When Mandy confronts it, it sucks out her brain.... but its aura immediately changes to resemble Mandy. Her only explanation is that she was [[TooSpicyForYogSothoth too "spicy".]]
** Likewise she does this to the "Delightful Reaper" in the KND crossover when she realizes it was too powerful for Kids Next Door's weaponry and ''willingly'' let it assimilate her. Like in the above example, it takes on her appearance.
* HornedHairdo: Making her look fittingly demonic.
* HypocriticalHeartwarming: She would never let Billy do any of the things that she does.
* ImprobableWeaponUser: In the Creator/CartoonNetwork game "The Fight Before Christmas", she uses a toy hammer, a toy plane, a doll[[note]]which she hurls like a throwing star[[/note]], a fistful of marbles and a pan of popcorn as weapons against the evil toys overrunning Santa's workshop.
* InformedDeformity: In ''My Fair Mandy,'' a skilled make-over artist was shocked by her appearance, at first mistaking her for an ugly tree stump.
* IronicName: Her name means "adorable" or "lovable", despite her bitter and cynical attitude.
* IronLady: Her ultimate goal in life is "[....] [[DesperatelyLookingForAPurposeInLife to do something]] [[YoungConqueror important]]!" She eventually is elected president of the United States, and in the distant future, will rule the world.
* {{Jerkass}}: She only had her few moments in the first couple of seasons but more and more after each one of them. Her beast transformation in "Sickly Sweet" even makes her sound like a ''literal'' ass (the animal). Hell, that episode shows that even trying to do anything nice is nearly impossible for Mandy, to the point where she has physical difficulty just trying to say "Please."
* JerkWithAHeartOfJerk: While she does do heroic actions like saving Billy from himself or whatever MonsterOfTheWeek they're up against, as well as saving the whole planet, Mandy will ''always'' have a selfish motive in mind no matter what -- but...
* JerkWithAHeartOfGold: ...she is also shown to care about Grim and Billy, even though she won't admit it and never talks about it. Another proof is that the real reason why she doesn't smile, is because the world would end if she did so.
* KarmaHoudini: RuleOfFunny usually dictates that she gets off scot-free -- [[KarmaHoudiniWarranty but there are a few occasions where she's outwitted and beaten]].
* LackOfEmpathy: Whatever empathy she has is locked away in the cold dark recesses of her soul.
* LittleMissBadass: Wears pink, is blonde, snarks almost constantly, and makes the Grim Reaper her personal bitch in the first episode.
* LittleMissSnarker
-->''"Power tools in the dark? Darwin should be paying you two goons royalties."''
* MaddenIntoMisanthropy: It's implied that two things helped complete Mandy's metamorphosis into the cynical tyrant we all know and love: Mindy's inane, meaningless prattle, and having to deal with Billy every single day of her life.
* ManipulativeBitch: She manipulated the Grim Reaper, Eris, Hoss, and sometimes even Irwin to do her bidding.
* NobleDemon: She's TheDreaded, brooding, anti-social and occasionally evil but she's also loyal and stays close to her friends, always keeps her word and never cheats.
* TheNoseless: But she does have nostrils.
* NotSoStoic: Some things ''can'' get under her skin, if rarely. Even she wasn't immune to being called ugly.
* OddFriendship: She willingly hangs out with Billy, despite the two of them being polar opposites.
* OffModel: She looks decidedly... wrong in ''Underfist''.
* OneWingedAngel: Her future self from the episode, "Mandy the Merciless" where she is a giant worm.
* OnlySaneWoman: Trades roles with Grim, depending on the episode.
* PerkyGoth: Completely {{Inverted}}; she dresses like a standard little girl, but embodies the Lone Psycho Goth stereotype.
* PerpetualFrowner: It's mentioned on more than one occasion that she ''never'' smiles; in fact, it's revealed in "My Fair Mandy" that if she ''does'' smile, it will cause a RealityBreakingParadox.
* PetTheDog:
** She will occasionally meditate on the possibility that she actually cares about Grim and Billy...[[IgnoredEpiphany but ultimately dismiss the errant thought.]]
** In "Halls of Time", she seems legitimately horrified at the idea of Irwin being erased from existence.
** Accepting Saliva (in her own way).
* PinkGirlBlueBoy: The pink girl to Billy's blue boy.
* PinkMeansFeminine: Averted. Mandy usually wears a pink dress, but she isn't that feminine.
* PragmaticVillainy: Oh she'll help save the world alright, but only because she needs it in pristine condition for when ''she'' conquers it herself. In the same vein, she'll always help defeat the MonsterOfTheWeek, but only because the world is ''hers'' and she won't let anyone else take it from her.
* PsychoticSmirk: By way of EarlyInstallmentWeirdness, but before it became a major defining trait of hers that she never smiles, she had a couple evil grins in response to Grim's suffering in "Meet the Reaper" and "Look Alive!".
* RedOniBlueOni: The blue to Billy's red.
* SlapstickKnowsNoGender: Though rarer than with Billy, she's not immune to physical comedy. Whether that's being [[AshFace burned to a crisp]] by Cerberus in "Mandy Bites Dog", or being [[CoveredInGunge covered in snot]] twice after Grim sneezes on her in "Night of the Living Grim".
* SociopathicHero
* TheSpock: Intelligent and deadpan.
* TheStoic: She never smiles fully at all. It's for the best.
* SugarAndIcePersonality: She is actually shown to be somewhat caring and even passionate in some episodes.
* TinyTyrannicalGirl: In fact, almost everyone in the show is afraid of her.
* TokenEvilTeammate: The only hero who's more evil than a demon from the underworld.
* TomboyWithAGirlyStreak: For someone so decidedly unfeminine, she has a tendency towards pink and girly things. While there's an underlying hint of irony to it, she seems to legitimately like them.
* TookALevelInJerkass: Mandy became more hostile and disrespectful towards her friends in later seasons.
* UnsympatheticComedyProtagonist: She has no positive qualities beyond being intelligent and competent, both of which she uses to make the world a bad place.
* VillainsOutShopping: Whenever she isn't scheming, she's just spending time, with Grim and Billy at their house.
* VillainProtagonist: When you make the personification of death look like a nice guy in comparison...
* WhenSheSmiles...she tears the very fabric of time, space, and reality apart. For the sake of humanity, it's better that she doesn't smile. Although in some earlier episodes, this trope is played straight.
* WhyDidItHaveToBeSnakes: In "Attack of the Clowns", both Billy and Grim claim that she's afraid of ''professional figure skaters,'' though she denies this, only saying she merely distrusts how they skate.
* WiseBeyondHerYears: She may be a real bitch but she's EASILY the smartest character on the show.
* YouGoGirl:
** Billy wouldn't allow Mandy in his baseball team because she's a girl. Trying to teach him a lesson, she disguised herself as a boy named "Manfred" by donning a baseball cap.
** Billy and Irwin made a racing team and wouldn't allow Mandy in because she's a girl so she started her own team with Grim, who was rejected from Billy and Irwin's for being a skeleton. [[SubvertedTrope Pud'n won]].

!!Other Characters

->Voiced by: Vanessa Marshall

A nerdy boy and a close friend of Billy's. He has a crush on Mandy. Later revealed to have monstrous heritage and becomes a crucial member of Underfist.
* AbhorrentAdmirer: Towards Mandy. All of the occasions of her reciprocating his feelings were either due to magical influence or [[DudeShesLikeInAComa being unconscious]].
* AccidentalHero: Him unintentionally suffering all of Mandy's pranks that were meant for Jack in the Halloween special is what ultimately leads to Jack being defeated.
* {{Adorkable}}: He's a nerdy boy who desperately tries to look cool and he also comes off as TheWoobie due to his relentless suffering.
* BlackAndNerdy: Though he's not that smart.
* BlackBestFriend: To Billy.
* BreakoutCharacter: Gets steadily more appearances until becoming the main character of ''Underfist''.
* ButtMonkey: Gets a lot of punishment along with Billy.
* TheChewToy: He is pretty much the [[WesternAnimation/SouthPark Kenny]] variant of this show.
* DarkIsNotEvil: He's a mish-mash of various monsters, but is almost always a harmless and obnoxious nerd.
* {{Dhampyr}}: At least, he is 1/4 Vampire (his paternal grandpa is Dracula).
* DoggedNiceGuy: To Mandy.
* EyeGlasses: His glasses will sometimes contort to his expression. His eyebrows will also overlap his glasses sometimes.
* FourTemperamentEnsemble: The Phlegmatic
* HalfHumanHybrid: 1/2 Mummy, 1/4 Vampire, and [[GeniusBonus 22/7]] nerd.
* JerkassBall: He can even be the villain of an episode if the situation calls for it.
* MadLove: Keeps a huge crush on Mandy, no matter how many times she rejects him.
* OurVampiresAreDifferent: Very much so. Just read the rest of this entry.
* RedEyesTakeWarning: [[spoiler:In ''Underfist''. And that's when [[BigBad Bun-Bun]] realized he was [[OhCrap screwed]].]]
* StalkerShrine: In the Halloween special, it is shown that he has one where hundreds of Mandy's eyes glare at him. It is one of the most disturbing things in the special.
* StalkerWithACrush: To Mandy.
* StrawLoser: He makes Billy seem cool in comparison. Even after we learn about all of his monster heritage, he still comes off as a useless loser (until ''Underfist'' anyway).
* SuperPowerLottery: Irwin's being a HalfHumanHybrid has given him several powers in ''Underfist'' such as: {{Flight}}, HandBlast (called Mummy's Curse), MummyWrap, SuperStrength and VoluntaryShapeshifting.
* TookALevelInBadass: In ''Underfist''.
* UsedToBeASweetChild: Inverted, believe it or not. In ''Heartburn'', Billy and Mandy play around with Grim's camera that shows the true self of the person on the film. Irwin's heart reveals to be half good like Billy's and half evil like Mandy's, and when questioned, he admits he was an EnfantTerrible at birth before his dad [[HeelFaceTurn turned him around]].
* VerbalTic: ...yo. Seems inherited; his dad calls people "dude", and his grandmama calls her loved ones "baby".
* VocalEvolution: In his earliest appearances, Irwin's voice was stuffier and he had a slight lisp. Eventually, his voice became a bit more clear, but still kept a unique sound.
* WithFriendsLikeThese: He's a pretty unreliable friend to Billy, to the point where he almost seems to hang out with him exclusively to be around Mandy. Billy's not that great of a friend to him either; he once stopped Sperg from giving Irwin a wedgie... So that ''Billy'' could do it for him.
* {{Yandere}}: When he got the scythe his first thought was to use it to brainwash Mandy and go on a forced date.

->Voiced by: Creator/RichardStevenHorvitz

Billy's father and Gladys' husband.
* {{Autocannibalism}}: In one episode, while picking his nose, he pulled his own brain out through his nose and proceeded to eat it.
* BumblingDad: Like his son, he often doesn't care about anything and has a small IQ.
* CloserToEarth: While he is dumber than Gladys, he is not as prone to fits of nervousness like she is and is quite relaxed around Grim.
* CrouchingMoronHiddenBadass: A former Navy SEAL.
* TheDitz: Billy got more than just his looks. This applies even before he TookALevelInDumbass considering he didn't seem to notice that Grim was actually the Grim Reaper!
* FatIdiot: He's not a stupid as his son, but he's close.
* {{Flanderization}}: He actually wasn't particularly stupid early on, just lazy and apathetic to the fact that his son was friends with the Grim Reaper. By later episodes, he's almost as dumb as Billy.
* HappilyMarried: To Gladys.
* HiddenDepths: In his youth, he was apparently smart enough to get accepted into Harvard University. [[spoiler: Too bad his acceptance letters were stolen by a sentient tree]] He was also a Navy SEAL at some point, as well as a world-class ballet dancer.
* MrViceGuy: He's overall a decent guy, even if he's disgusting and rather stupid.
* NoodleIncident: He once [[spoiler:dressed up like Sasquatch, kidnapped Billy and did something to him that left him with "emotional scars"]]. This might explain why [[spoiler:his wife thinks she's had an affair with Sasquatch]] too.
* OnlySaneMan: In the early episodes, before the above mentioned Flanderization, he was this compared to his wife and son.
* RedOniBlueOni: The blue to Gladys' red.
* StrongFamilyResemblance: He's an older, fatter Billy with a pompadour.
* TookALevelInDumbass: Starts out as reasonably intelligent, but eventually becomes much dumber.
* UglyGuyHotWife: His wife is considered quite attractive by some while he looks almost exactly like an older, fatter version of Billy.

->Voiced by: Creator/JenniferHale

Billy's mother and Harold's wife.
* AmbiguousDisorder: She's implied to be the source of Billy's psychopathic outbursts.
-->'''Harold:''' Did someone forget to take their medicine today?
* AngerBornOfWorry: Her angry side was born from her worry of Grim, and she learned to not fear him, but destroy him.
* DotingParent: She is a caring but overprotective mother to Billy.
* FieryRedhead: She can even make Grim run away in terror.
* HappilyMarried: To Harold.
* MamaBear: Mostly in the earlier seasons. If she considers you a danger to Billy, she will do everything in her power to make sure you stay ''as far away from him as possible''. It's one of the main reasons why she hates Grim so much, and wants him out of her house.
--> '''Gladys:''' ''(after beating Grim over the head with a mop)'' STAY AWAY FROM MY BABY!!! He's allergic to the undead!
* NoodleIncident: Apparently, Gladys has had some sort of...[[GettingCrapPastTheRadar less than wholesome liaison]] with [[InterspeciesRomance Sasquatch]], which is referenced in an episode wherein Billy grows a whole lot of hair and Gladys mistakes him for Sasquatch. [[spoiler:Though given this strange little "hobby" her husband has, it's possible that it was actually him in disguise]].
-->'''Gladys:''' (''attacking Billy thinking he's Sasquatch'') I TOLD YOU IT IS ''OVER'' BETWEEN US!
* ProperlyParanoid
* RedOniBlueOni: The red to Harold's blue.
* SelfServingMemory: She remembers the circumstances that led her to leave a ''little'' differently than they actually happened.[[note]] Grim's presence did drive her to a mental breakdown but that was largely due to ContrivedCoincidence making it look like she was losing her mind and deciding to leave for the sake of her own sanity while upon her return she makes it out that Grim was deliberately tormenting her and chased her out rather than leaving voluntarily [[/note]]
* StepfordSmiler: Type 3. She tries to maintain a sense of normalcy and care for her family, but is always close to going over the edge because of Billy's antics. That smile ends up being frozen and forced much of the time as a result.
* SuperOCD
* TwitchyEye: She has this whenever something goes wrong or the supernatural happens.
* UglyGuyHotWife: She is considered quite attractive by some, while Billy's dad, Harold, looks almost exactly like an older, fatter version of Billy.
* WomenAreWiser: Subverted. While smarter than her husband, she's also mentally unstable and prone to fits of homicidal rage (which she passed t her son.)

->Voiced by: Creator/RachaelMacFarlane

The goddess of chaos. She possesses the powerful Apple of Discord, a golden apple which can transform into any shape to perpetuate chaos. Grim used to have a crush on her during earlier episodes, but later changes his mind, claiming her to be a "psychopath". She is also in love with Hoss Delgado, who reciprocates but finds her to be too dangerous.
* AlphaBitch: Gave off this vibe in her debut episode.
* AlwaysChaoticEvil: The only person who's more chaotic than her is Billy, and the only person more evil than her is Mandy.
* ArtEvolution: She looks quite a bit different in her second appearance. She looks different again in her third.
* ArtifactOfDoom: The Apple of Discord, a golden apple which can transform into any shape to perpetuate chaos (though Billy calls it a "magic banana").
* BareYourMidriff
* BigBad: Of just about every episode she plays a major part in.
* EvilMentor: Frequently uses Mandy as an agent for spreading chaos, though she always does it in secret after her first episode. She attempts to do the same with Billy at one point, only to find that he's ''too'' chaotic and unpredictable to manipulate effectively.
* ForTheEvulz: She's the Goddess of Chaos, which pretty much means it's her job to screw with the lives of mortals for fun.
* HotGoddess
* ImpossibleHourglassFigure: She has a curvaceous and beautiful body.
* JerkassGods: Lives solely to cause chaos and destruction.
* LiteralSplitPersonality: {{Word of God}} confirmed if ''Underfist'' had gone to series, Eris would split herself into two different versions of herself (a good version and an evil version) after being heartbroken from her break up with Hoss Delgado as the two versions attempt to win back Hoss's love each in their own crazy and chaotic ways. You can see them during the closing credits.
* MsFanservice: She's a curvy woman in a revealing outfit.
* NoCelebritiesWereHarmed: Her appearance and personality are based on {{Music/Madonna}}.
* PhysicalGod: While she generally relies on her apple to cause chaos, she is shown capable of doing essentially anything on her own, but simply chooses not to because it's more fun to watch chaos unfold rather than cause it herself.
* RealityWarper: Comes with the territory of being an evil chaos goddess.
* {{Trickster}}: Lives to screw with humanity.
* ValleyGirl: Eris's accent turning from a Valley Girl accent to a British accent may be a reference to Madonna, who started speaking in a British accent later on in her music career.
* WeCanRuleTogether: Offered it to Mandy in one episode. Mandy considered it but when told she'd be the "second most powerful person in the world", [[ThereCanOnlyBeOne she promptly refused.]]
* WomanInWhite: Wears a completely white toga.
* {{Yandere}}: Her reaction to being dumped by Hoss? Turn into a giant bug and eat him.

[[folder:Hoss Delgado]]
->Voiced by: Creator/DiedrichBader

A spectral exterminator who frequently encounters Grim, Billy and Mandy in his various exploits, and briefly dates Eris, Goddess of Chaos. Later becomes part of the Underfist team, albeit reluctantly at first.
* AccidentalMisnaming: In ''Underfist'', he keeps getting Irwin's name wrong. He calls him "Irving", "[[ShoutOut Ur]][[Series/FamilyMatters kel]]", and "Ivan". [[spoiler:He correctly calls him "Irwin" while saving him from the giant pumpkin-headed candy monster.]]
* ArtEvolution: He's noticeably older looking in ''Underfist'', sporting a beer gut and streaks of grey in his hair. He's also even larger than before and has a chainsaw leg.
* AntiHero: He believes that all monsters are a threat, which causes him to murder any monster he ever sees, even innocent and harmless ones.
* AwesomeMcCoolname: His name is a pretty good indicator of his outrageous badassery.
* BigBrotherMentor: Acts as a rather half-assed one to Billy in a few episodes, and Irwin in others.
* BunnyEarsLawyer: He's a tad eccentric and not very bright, but he is a ''damn'' good spectral exterminator.
* CharacterizationMarchesOn: He's presented as a bit of an incompetent buffoon in his first appearance. In all of his following ones he is shown to be extremely competent at his job, with most of his humor being derived instead from his excessive and ridiculous monologues.
* TheComicallySerious: His lines are almost always ridiculous, but delivered in a completely serious BadassBaritone.
-->''"I've been bitten by ghosts, haunted by mome raths and slapped by vampires... '''I think I've earned a free hotdog.'''"''
--> ''"Are you stepping in my cornflakes? I'll tell you something about stepping on someone's cornflakes... '''it's a weird way to eat cornflakes'''"''
* DatingCatwoman: His relationship with Eris.
* DarkAndTroubledPast: Parodied. He has an exceedingly long and convoluted one that is also ridiculously lame, involving wetting the bed till he was 35, being raised as a girl for most of his childhood, poking his eye out after running with scissors and getting constantly one upped by ''a traffic cone''.
* DumbMuscle: He's far from the brightest bulb, but is an excellent fighter.
* EmpoweredBadassNormal: He replaced his own hand with an Iron fist that can turn to all sorts of weapons from a gun to a ''chainsaw''. He also replaced his leg with a chainsaw in ''Underfist''.
* EyepatchOfPower
* {{Expy}}: Of [[Film/EscapeFromNewYork Snake Plissken]] and [[Franchise/EvilDead Ash]] at the same time!
* GoKartingWithBowser: Despite his hatred of Grim, he's perfectly willing to pal around with him when the situation calls for it.
* GoodIsNotNice: He is seemingly the only person in the world who fights supernatural threats besides the main trio, who are more often than not the cause of them, but mercilessly hunts even harmless ones like Jeff and Fred and tends to act like an indifferent jerk to other people. This changes after Irwin saves his life in ''Underfist'', making Hoss realize that there are some good monsters after all.
* {{Hammerspace}}: Where he keeps all the random attachments for his hand (his chainsaw, goo cannon, crossbow that fires a ''chainsaw'').
* HeroAntagonist: It varies. His hatred of Grim puts him at odds with the trio on occasion, but he can be an ally just as frequently, if not more.
* HiddenDepths: Despite being a powerful tough guy, one of his favorite things is Pat the Baker, a simplistic baking video game that is also Billy's favorite game. According to him, he never leaves home without it and he and Billy bond over playing it at the end of an episode.
* {{Hunk}}: According to Eris. He's so obscenely muscular and hairy that he can be easily mistaken for bigfoot when shirtless.
* {{Narcissist}}: He's pretty self absorbed, to the point where his debut has him trying to justify a reason for a random street vendor to give him a free hot dog.
* OneManArmy: Generally has an easy time taking out hordes of supernatural monsters, though he has quite a bit more trouble dealing with Eris.
* PermaStubble: Pretty much a given, considering who he's based on.
* PreAssKickingOneLiner: When he isn't belting out complicated and bizarre metaphors that don't apply to the situation, he's delivering really campy one liners.
* SourSupporter: Did ''not'' want to be part of Underfist, but President Mandy ordered him; by the end, he's warmed up to the idea.
* SwissArmyAppendage: His cyborg hand (it was outright called his "Swiss Army Hand" in his video game profile). It can transform into a variety of things, ranging from a chainsaw-firing crossbow to a nose-shaped detector to a bouquet of flowers.
* TankGoodness: His giant fist-and-arm shaped tank which provides Fred Fredburger the idea for the Underfist team. It later gains a blue-and-yellow paint job, but got wrecked by one of Bun-Bun's rotten gems.
* TheStoic: Most of the time.
* TragicHero: His gruesome experiences with monsters has caused him to attempt to destroy every monster he sees, even harmless ones. This often gets him to become a HeroAntagonist.
* TookALevelInBadass: In the past. He used to be a loser like Irwin, until he became the Hoss we know.
* TookALevelInDumbass: He was never particularly smart, but ''Underfist'' takes it a step further.
* TopHeavyGuy: His upper body becomes bigger and bigger while his legs become tinier. By ''Underfist'' he's obscenely beefy and supported by two tiny tooth pick legs.
* VanHelsingHateCrimes: He's a spectral exterminator, hunting monsters for a living. The problem being that not all of them are ''bad''; [[DontFearTheReaper Grim]], for instance. He even took out a bunch of ''lawyers'' because he said they weren't human. Even after he retired from his profession, he still holds some prejudices towards monsters. In ''Underfist'', he refuses to let Jeff and Fred Fredburger come with him to the Underworld because he doesn't work with monsters (or "[[HypocriticalHumor one-eyed weirdos]]", in Skarr's case). He also hesitates in joining Underfist because of this. [[spoiler:There's also his fights with Irwin, and the fact he tried to ''kill'' Irwin once he found out he was a vampire ''and'' a mummy.]]
--> '''Hoss:''' [[spoiler:[[AccidentalMisnaming Ivan]] is a [[HybridMonster mummy-vampire]]? That means you lied to me ''twice'' when you said you weren't a monster!]]
* TheWorfEffect: Very present throughout ''Underfist''.


->Voiced by: Fred Willard

An old arch-enemy of Grim's since middle school, and a former school bully, Boogey played pranks on Grim throughout his school career. Boogey is, in fact, the Boogeyman himself, and can shapeshift in order to scare people.
* ArsonMurderAndJaywalking: He blames his inability to scare children on TV, video games, and the ''tuba.''
* BigBad: Of the first movie (interviews with Maxwell stated that ''[[Film/StarTrekIITheWrathOfKhan Wrath of Khan]]'' was what inspired him to use him since he appeared in only one episode). He was also indirectly responsible for the events in the second one.
* FauxAffablyEvil
* HumiliationConga: [[spoiler:What happens to him in the climax of the first film. It is so too much for him that the epilogue states that he got completely traumatized for life.]]
* JadedWashout: He tends to boast he used to be way scarier than Grim in their middle school years, but nowadays he is just a second-rate monster that can't even scare one single child (except for Billy and Mandy's friend, [[TheChewToy Irwin]]).
* {{Jerkass}}
* LackOfEmpathy
* LeanAndMean
* {{Pirate}}: His motif in the first movie.
* TheRival: To Grim.
* TheSociopath
* SmallNameBigEgo: See JadedWashout.
* SmugSnake
* VillainousBreakdown: After the [[spoiler:aforementioned HumiliationConga.]]
* WhyDidItHaveToBeSnakes:[[spoiler: Boogie's worst fear is people not finding him scary.]]
* WouldHurtAChild

[[folder:General Skarr]]

->Voiced by: Armin Shimerman

[[WesternAnimation/EvilConCarne Hector Con Carne's ex-paramilitary commander]]. He moved to Endsville after Con Carne's organization shut down, and became Billy's neighbor (much to his distress) and an avid gardener. Later joins the Underfist team.
* AntiHero: In "Underfist". (Type V in fact)
* BadassBeard: In "Underfist".
* BaldOfEvil
* BerserkButton: In the name of all that is good, do ''not'' mess with his garden.
* ButtMonkey
* CanonImmigrant: The only ''Evil Con Carne'' character to get elevated to recurring status here.
* FakeDefector: Does this towards Bun-Bun in ''Underfist''.
* GoodHairEvilHair: Gains a handlebar moustache and a goatee in ''Underfist''.
* MeaningfulName
* TheNeidermeyer/TheStarscream: Was like this back when he worked for Hector Con Carne. He [[ExploitedTrope exploited the trope]] in ''Underfist''.
* RealMenWearPink: Is often seen gardening his front yard happily.
* ScarsAreForever
* SissyVillain: A megalomaniac who knows his way around an attractive garden.


->Voiced by: Creator/RachaelMacFarlane

An obnoxious and snobby girl from Billy and Mandy's school that is obsessed with proving her worth to Mandy, who doesn't care for her.
* AlphaBitch: A much younger AlphaBitch, as well as an incredibly obsessive one. For example, she loses her head cheerleader position to Mandy (who just shouts the game plans to the team) and, after consulting the "patron saint of cheerleading" (a trophy she thinks is talking), decides the best solution is to incapacitate her in some way in the middle of a match, or, failing that, blow her up. If she sees Mandy with anyone aside from Billy or Irwin or the like, she walks up to them, puts on an obscenely perky face, and says "You're my best friend!"
* AssholeVictim: Thankfully, she's also one of the show's regular victims of whatever supernatural power is at hand in the episode.
* BrattyHalfPint: Falls right into this category.
* DisproportionateRetribution: When Mindy first moved in Endsville, Mandy actually tried being nice to her because she looked alone. She quickly regretted it hearing her chatterbox antics and told her to shut up. Mindy didn't take it well, and had became her obnoxious rival ever since.
* EvilRedhead: She has ginger colored hair and is a nasty, downright obnoxious AlphaBitch.
* {{Foil}}: To her rival Mandy. They have similar names and both of them are mean and rude, but otherwise they are complete opposites: Mindy is a GenkiGirl in contrast to Mandy's EmotionlessGirl; Mindy is shallow, spoiled, and stupid while Mandy is dark, cynical, and intelligent.
* GenkiGirl: A rare evil variant.
* {{Jerkass}}: She constantly torments Mandy in a verbal manner (In fact, her catchphrase is "LOSER!") and taking it all in stride.
* HeelFaceTurn: At the end of "Underfist".
* LickedByTheDog: A subversion in one episode in which this literally happens and she responds by acting even ''worse'' than usual!
* PopularIsDumb: "But as beautiful and popular as I am, I bet there are some people who've never even heard of me: people in countries like Paris or Toronto, or in cities like Africa."
* RichBitch: She is the evil, rich and spoiled queen bee of the school.
* TheRival: For Mandy, at least.
* SchoolUniformsAreTheNewBlack: Is almost always seen in her school clothes.
* TookALevelInBadass: Twice in a row; in both "Wrath of the Spider Queen" and "Underfist".


->Voiced by: Jane Carr

A classmate of Billy and Mandy's, Pud'n is a very sensitive young boy who is constantly picked on by Sperg.
* BewareTheNiceOnes: He got into an epic struggle with a demon rabbit and causes an explosion by squirting the custard out of two éclairs, and he once viciously beat up General Skarr when he thought Skarr was responsible for turning all his neighborhood rabbit friends into monsters.
* ButtMonkey
* BrownBagMask: He wears one while competing in a go-kart race with the other kids. He miraculously wins, despite his go-kart being nothing more than a simple red wagon. Mandy ends up unmasking him, and he starts crying like a baby when he sees everyone cheering for him.
* InTouchWithHisFeminineSide: He's weak, completely non-aggressive, loves fluffy pink bunnies, and cries at the drop of a hat.
* RaisedByWolves: In one episode, Billy asks what Pud'n is doing outside so late at night, only for Pud'n to show that he was raised by wolves, and they live outside. The wolves are watching television and one politely waves at Billy, telling him good evening.


->Voiced by: Greg Eagles

The local bully, who constantly bullies Billy, Irwin, Pud'n, and other kids to no end.
* BerserkButton: Don't talk bad about his mom, especially if it causes her to cry right in front of him.
* TheBully: He is often seen tormenting Billy, Irwin, or other kids.
* EvenBadMenLoveTheirMamas: He's very defensive of his mother.
* EvilRedhead: Has red hair and is a bully.
* HeroicSacrifice: [[spoiler: Saves the world from alien invaders by using the explosive chip in his head. [[MadeOfIron He manages to bully people without a head]]]].
* JerkAss: To most kids, but primarily to Billy, Irwin and Pud'n.
* JerkWithAHeartOfGold: In the episode where he and the rest of the cast fight off aliens, he gets a bomb planted in his skull that explodes in a day's time...all while Billy whomps the other aliens mercilessly. What does Sperg do? Make his way to the control room, where he eventually detonates, blasting the alien ship out of the sky.
* RealMenWearPink: He loved to sing showtunes. In "Tricycle of Terror," he expresses a desire to be on Broadway.


->Voiced by: Creator/DavidWarner, later Martin Jarvis

A black-skinned supernatural being with green eyes who wears a business suit. He has the ability to shapeshift, with which he can create several tentacles from his back that can electrocute his victims or turn them into beings looking like himself. [[IJustWantToHaveFriends What Nergal desires most is having friends]], once stating that it is quite lonely in the center of the world. However, he gets better once he starts a family.
* AffablyEvil: He's generally polite, even around his victims.
* AntiVillain
* BeneathTheEarth: Lives in the Earth's core.
* CharacterDevelopment: Starts off as an AntiVillain, but ends up becoming a friendly member of Billy's extended family who usually means no harm. This primarily came after he began a family of his own.
* CrazyJealousGuy: "Son, it's not about you liking a girl, or a girl liking you. What's important is that she can ''never get away from you''."
* CombatTentacles: He can sprout the from his back.
* EldritchAbomination: He's a black creature from the center of the earth with electric tentacles (some of which have ''mouths''), removable organs and the ability to turn people into members of his kind.
* GoodParents: He's this to Junior.
* HappilyMarried: With Aunt Sis.
* IJustWantToHaveFriends: PlayedForLaughs.
* InterspeciesRomance: With Billy's Aunt Sis.
* LargeHam: He was originally voiced by ''David Warner'', this comes with the territory. Toned down a bit after Martin Jarvis took over.
* ShockAndAwe: Can electrocute people with his tentacles.
* ShoutOut: To a Mesopotamian deity of the same name.
* StalkerWithoutACrush: He wanted Billy and Mandy to be his friends long before he was officially introduced to them.
* {{Yandere}}: Like father, like son.

[[folder:Nergal Junior]]

->Voiced by: Debi Derryberry

The son of Nergal and Billy's aunt Sis. As a result, he is Billy's first cousin.
* {{Adorkable}}: Generally comes off as a fairly sweet, awkward kid when not violently attacking others.
* BeneathTheEarth: Like his father, he lives at the Earth's very core.
* BerserkButton: Do ''not'' call him a freak or say he's hideous. Seriously, just don't.
* CheshireCatGrin: And how!
* CombatTentacles: He's Nergal's son afterall.
* CreepyChild: He is able to turn into almost anything and is extremely creepy. His true form (although it's rarely seen) is very horrid to see.
* CuteMonsterBoy: An adorable and dorky boy who happens to be a demon spawn. Unlike Irwin (who is also this), he's also kind of creepy.
* EldritchAbomination: Even more so than his father; he can shapeshift, walk through walls, spawn bat-like imps from his body and freeze people in supernatural stasis.
* EyeGlasses: Just like Irwin, Junior's eyeglasses change shape depending on his expression.
* GlamourFailure: No matter what form he uses, he keeps his glasses, yellow eyes, sharp yellow teeth, and green tongue.
* HalfHumanHybrid: Half human, half demonic entity or whatever Nergal is (Jr could count as a demigod if one believes Nergal is the Mesopotamian god he's named after)
* IJustWantToHaveFriends: Unlike his dad, ''not'' played for laughs... [[ReverseCerebusSyndrome at first]].
* LonersAreFreaks: "Freak" is pretty much his nickname, but also his BerserkButton.
* NiceGuy: One of the kinder characters on the show, but also a severe {{Yandere}} for friendship.
* OneWingedAngel: His true form, which is so grotesque and deformed that it's rarely, if ever, seen onscreen.
* OnlyFriend: Billy is the only character who treats him like a person, though even he immediately freaks out upon seeing his true form.
* ShapeshifterDefaultForm: The form of the first kid he tried to befriend (and subsequently did away with when he was rejected).
* VoluntaryShapeshifting
* {{Yandere}}: Initially portrayed as violently attacking anyone who mistreated him, but becomes somewhat more passive in later episodes.

[[folder:Aunt Sis]]

->Voiced by: Creator/GreyDeLisle

Harold's sister and Billy's Aunt, who later marries and starts a family with Nergal at the center of the Earth.
* EveryoneCallsHimBarkeep: Her real name is never given. She's named by her relation to Billy's family. She's Billy's aunt and Harold's sister.
* HappilyMarried: To Nergal.
* MaidenAunt: Before marrying Nergal. Gladys explicitly calls her a spinster when explaining to a curious Billy as to why she "ain't got nobody". PlayedForLaughs in that she met her true love during a dance contest, and he left her once the contest was over. Gladys explains this was the "Greatest four and a half minutes of her life"

[[folder:Jeff the Spider]]

->Voiced by: [[CreatorCameo Maxwell Atoms]]

A man-sized spider that Billy hatched from an egg who quickly imprinted on Billy. Later tried to "grow up", with mixed results, and joined Underfist.
* {{Adorkable}}: A GiantSpider with a heart of gold and no desire beyond to be loved by his adopted father, Billy.
* BewareTheNiceOnes: As seen in "Spider's Little Daddy", and to a lesser extent ''Underfist''.
* FemaleMonsterSurprise: In "Jeffy's Web".
* GiantSpider: The size of a man.
* GrowingUpSucks: What he and Fred realize in ''Underfist''.
* NiceGuy: Jeff is described by Mandy as being both "too nice" and "basically insane".
* SelectiveObliviousness: He seems completely incapable of understanding that Billy hates spiders, including Jeff himself, to the point of madness, despite the fact that Billy regularly beats him with anything he can get his hands on.
* ThoseTwoGuys: With Fred in ''Underfist''. Which is strange considering the two had no interaction before that.
* WellDoneSonGuy: His only real goal in life is to really have Billy love him like a son. Of course, when your dad is violently terrified of you, that isn't going to be easy.

[[folder:Fred Fredburger]]

->Voiced by: C.H. Greenblatt

A dimwitted, pale green, bipedal furry otherworldly creature resembling an elephant with stubby horns and the tail of a devil. Ends up forming Underfist just via a drawing.
* AlliterativeName
* BreakoutCharacter: Maxwell Atoms even referred to him as such.
* CatchPhrase:
** "Yes!"
** "Fred Fredburger, Fred Fredburger, Fred Fredburger, Fred Fredburger, [[OverlyLongGag Fred Fredburger]], [[BrokenRecord Fred Fredburger]], [[MadnessMantra Fred Fredburger]]..."
* CloudCuckooLander: Is primarily fond of nachos and spelling his own name "real good".
* TheDitz: Even Billy is smarter than him and that REALLY says something.
* DumbassHasAPoint: His original idea for the Underfist team is originally dismissed by Skarr as "childish nonsense", but Jeff saw potential in the idea- that Earth needs defenders from all the threats the Underworld spews out.
* {{Flanderization}}: Averted. Though his classic name-spelling gag is repeated in almost all of his appearances, he was nowhere near as overused and ended up becoming hated as, say, [[WesternAnimation/FostersHomeForImaginaryFriends Cheese]].
* GrowingUpSucks: What he and Jeff realize in ''Underfist''.
* FromNobodyToNightmare: [[spoiler:He becomes the Lord of Horror in the BadFuture]].
* {{Keet}}: He's a hyperactive, elephant-like monster.
* MommasBoy: He lives with his 'mama'.
* ThePollyanna
* PottyEmergency: "'''[[PunctuatedForEmphasis I HAVE! TO MAKE! POO-POO!]]'''"
* ThoseTwoGuys: With Jeff the spider in Underfist.
* TrademarkFavoriteFood: Nachos and frozen yogurt, yes!
* VerbalTic: "Yes!"

[[folder:Jack O'Lantern]]

->Voiced by: Creator/WayneKnight

The main antagonist in the Halloween special, ''Billy & Mandy's Jacked Up Halloween''.
* BigBad: Of the first Halloween special.
* TheCameo: Subverted. He doesn't get screen time or lines, per se, but is briefly mentioned in ''Big Boogey Adventure'' during the trial scene, when Boogey lists off everyone who has stolen Grim's scythe.
* DisproportionateRetribution:
** The members of his own town saw to it he was executed just because he didn't know when to stop pranking them. Pretty dark, given the silliness of the show in general. Demonstrated when [[spoiler: he's sent to the underworld. This is still a bad habit of his and got his pumpkin head squashed. So it was bound to happen sooner or later.]]
** His pranks ''were'' causing people injury; tricking a guy off a ''cliff''.
* EvilIsHammy: He's voiced by Wayne Knight. Of course he's this.
* EvilLaugh
* HoistByHisOwnPetard: When Grim came to collect him the first time, he managed to stop him with a feather leading into the deal to give him immortal life. At the end of the special, Grim uses a feather to send Jack to the underworld.
* TheHyena: He treated everything in life as a potential joke to the extent that he laughed in his sleep. This did change however after his bitterness for losing his head made him more jaded and abrasive.
* InnocentlyInsensitive: Implied that, before decapitation, he didn't understand that he was hurting people or that people were growing sick of him, to the point of wanting to kill him. He just kept pulling pranks and making jokes with a happy smile and laughed himself to sleep, he thought he was being genuinely funny. Despite all that laughter he was causing himself, the town didn't find his harmful pranks funny.
* FreudianExcuse
* {{Jerkass}}: He is a trickster, playing pranks and tricks for amusement. He was also shown using it to get what he wanted, such as when he tricked Grim into giving him immortality.
* OffWithHisHead: Via Grim
* ThePrankster: Of the evil variety.
* PumpkinPerson: After a deal with Grim (returning his scythe in exchange for immortality), Grim cut off Jack's head. He then replaced it with a Jack-O' Lantern.
* PungeonMaster: After Jack captures Grim, and gets ready to [[OffWithHisHead decapitate him with his own scythe as revenge]], he starts letting out [[HurricaneOfPuns a whole series of head-related puns]]. Grim is understandably not amused.
* WhoWantsToLiveForever: "Three hundred and sixty-four days a year, I can't even go the the ding-dong grocery store to buy pudding. And do you know why?" Of course it's not so much living forever then "living forever with a pumpkin for a head".
* WhyDidItHaveToBeSnakes: He has a crippling fear of knights, specifically the one that was sent to execute him all those years back. When he believes said knight had returned for him he was too frightened to fight back despite having the Grim Reaper's scythe in his hands.


->Voiced by: Creator/PhilLaMarr

Irwin's grandmother, more commonly known as "Grandmama."
* BadassGrandma: You qualify as this if you're able to get [[spoiler: Dracula, your husband]] to shut up and just eat their dinner.
* CoolOldLady: Unlike many of the adults on the show.
* CurbstompBattle: Delivered one of these to Principal Goodbling.
* FourthDateMarriage: With [[spoiler: Dracula]].
* IWasQuiteTheLooker
* ThirdPersonPerson: Occasionally.


->Voiced by: Creator/PhilLaMarr

A vampire that was Grim's childhood hero.
* BreakoutCharacter: Introduced as part of the old horror icons alongside Frankenstein's bride and the Wolfman. But thanks to Phil hitting the role so enthusiastically, he made more appearances, completely eclipsing the Bride and Wolfman, even having a [[spoiler: family connection to Irwin]]. He was even used for part of Cartoon Network's live action Halloween promos via a puppet.
* DaywalkingVampire: Except for "Fear and Loathing in Endsville" and a brief moment in his first appearance, he doesn't seem to be harmed by sunlight.
* {{Dracula}}: [[CaptainObvious Duh.]]
* DisappearedDad: To [[spoiler: Irwin's dad.]]
* {{Expy}}: Of ''Film/{{Blacula}}'', the joke being he bears his name despite not looking at all what most media make of him. For extra HilariousInHindsight, in the Blacula movie, Dracula is the one who turns Blacula.
* GrumpyOldMan
* {{Jerkass}}
* JerkWithAHeartOfGold: On occasion, such as sucking poison out of Grim or giving Irwin advice on accepting his monster heritage.
* JerkWithAHeartOfJerk
* LukeIAmYourFather: Grandfather, to be precise. [[spoiler:Namely, Irwin's.]]
* NoCelebritiesWereHarmed: Redd Foxx
* OurVampiresAreDifferent: Yup. Not only is he both Redd Foxx and Blacula, but he (most likely) [[AccidentallyAccurate coincidentally]] resembles the novel version of Dracula more than most interpretations.
* PsychopathicManchild: Is he ever.
* ScrewPolitenessImASenior
* ScrewThisImOutOfHere: When his wife beat him to a pulp (not knowing he could turn into a bat), once he was far away from her, he took off, in fear of her attacking him again.
* ThirdPersonPerson

[[folder:Nigel Planter]]

->Voiced by: Jake Thomas

A ''Literature/HarryPotter'' parody who resides at Weaselthorpe House at Toadblatt's School of Sorcery.
* ArchNemesis: Lord Moldybutt [[spoiler: WOULD be this except for that he's a real estate agent]].
* TheChewToy: Nothing ever goes right for him.
* LetsMeetTheMeat: He's a partial-tongue, allowing him to talk to snacks.
* ScarsAreForever. Lord Moldybutt gave him a scar when he was a child.[[spoiler:.. except not since it's just a pen mark and gets rubbed off fairly easily]].
* SmallNameBigEgo: Prides himself as the greatest wizard in the world, but is generally seen as a joke until being kicked out of Toadblatt's entirely by the time of "Order of the Peanuts."
* SoapOperaRapidAgingSyndrome: Hits puberty and doubles in height sometime before the events of "One Crazy Summoner."

[[folder:Sir Raven]]

->Voiced by: Julian Stone

A raven that occasionally narrates episodes.
* CreepyCrows: Well, duh.
* DeadpanSnarker
* LargeHam: "Let's watch a clip. [[SuddenlyShouting WATCH! A! CLIP!]]"
* LemonyNarrator
* GiantSpaceFleaFromNowhere: He just kind of... appeared in "Tricycle of Terror", then started to appear some more. The fans adore him, though, so it's not a big problem.
* GreekChorus
* HiddenDepths: If "Tricycle of Terror" is to be believed, he has a soft spot for Billy.
* PunctuatedForEmphasis: "IMPORTANT! COMMERCIAL! MESSAGE!!!"
* QuintessentialBritishGentleman: Looks the part, but lacks the personality.
* TheStoryteller
* SuddenlyShouting: His specialty.
-->'''Sir Raven''': Alas, poor Billy, destined to walk the sepulchered streets of suburbia! A doomed husk of a child, do not cry for him! '''''DO NOT CRY!!!'''''