!Main characters

[[folder:Osmosis "Ozzy" Jones]]
->'''Voiced by:''' Creator/ChrisRock
* BlueIsHeroic: Even though he's a white blood cell, his color is a light shade of blue.
* CheshireCatGrin: He sports one of these every now and again.
* CoolCar: Had his cop car customized.
* CoolShades: Occasionally wears a pair of black sunglasses.
* CowboyCop
* {{Determinator}}: Chases down Thrax ''outside Frank's body''.
-->'''Thrax:''' You just don't know when to ''quit'', do ya, Jones?
* DoggedNiceGuy: Has trouble winning Leah Estrogen's affections. [[spoiler: He does at the end, though.]]
* TheHero
* InkSuitActor: He's essentially Chris Rock as a white cell.
* InSeriesNickname: Always known by "Ozzy".
* NiceJobBreakingItHero: He did the right thing [[spoiler: causing Frank to vomit, thereby saving him from a contaminated oyster]], but it caused Frank to lose his job and the respect of the local community, and [[NoGoodDeedGoesUnpunished got Ozzy suspended for "use of unnecessary force"]].
* OfficialCouple: With Leah at the movie's end.
* ProtagonistTitle: For the film. In the animated series he shares the title with Drix.
* RedOniBlueOni: The red to Drix's blue.
* SensitiveGuyAndManlyMan: The Manly Man to Drix's Sensitive Guy.
* SesquipedalianSmith
* ShapeshifterShowdown: What saves him against Thrax.

[[folder:Drixenol Koldreliff]]
->'''Voiced by:''' David Hyde Pierce
* ArmCannon: How he utilizes his icy painkilling abilities.
* TheBigGuy:
* ByTheBookCop: Part of what makes him different from Osmosis.
* CaptainErsatz: Drix bears a strong resemblance to ComicBook/IronMan.
* GeniusBruiser
* AnIcePerson: His painkilling abilities are portrayed as this.
* InSeriesNickname: "Drix" is this, short for Drixenol (or Drixobenzometaphedramine).
* TheLancer
* RedIsHeroic: His main colors are red and yellow.
* RedOniBlueOni: The blue to Ozzy's red.
* SensitiveGuyAndManlyMan: The Sensitive Guy to Ozzy's Manly Man.
* SlasherSmile: When pretending to be crazy to extract information from a flu vaccine.
* TheSmartGuy: He certainly acts smarter than Osmosis, at least. To be fair, he is intelligent and educated, Ozzy just has more experience, and Drix listens to him when it is prudent to do so.

!Movie characters

->'''Voiced by:''' Creator/LaurenceFishburne
* AssKickingEqualsAuthority: He gets the bacterias to accept him as their leader after he single-handedly killed their boss.
* AxCrazy: When it comes to Thrax and his desire to get in the medical books he will pile up as many bodies as he can, and he will do it all with a gleeful smile on his face.
* BadassBoast: When Scabies mocked Thrax, saying he thinks himself the Ebola Virus.
-->'''Thrax:''' "Ebola"? Let me tell you a little something about ''Ebola'', baby. Ebola's a case of DANDRUFF COMPARED TO ME!
* BadassLongcoat: One he can even use as a ''glider''.
* BadBoss: He kills all his remaining underlings when one of them suggests waiting for some days in incubation before striking.
* BerserkButton: Do not get in the way of his goal of being in the medical books. [[BadBoss He killed all of his men when one suggests they incubate]]. He doesn't take kindly to being looked down on, as Scabies found out.
-->'''Scabies:''' Look who thinks he's the Ebola virus! (laughs)
-->'''Thrax:''' ...Ebola? Let me tell you a little something about Ebola, baby: '''[[SuddenlyShouting EBOLA IS A CASE OF]]''' '''''[[SuddenlyShouting DANDRUFF]]''''' '''[[SuddenlyShouting COMPARED TO ME!]]'''
* BigBad: He's the reason why Frank is in danger.
* BigNo: Does this when Ozzy traps him on the girl's fake eyelash that is about to fall.
* BondVillainStupidity: Rather than using his OneHitKill claw on a dazed Ozzy during the final battle, he decides to strangle him using his chain. This costs him big when Frank's daughter blinks: he loses his grip on the chain, and when he decides to actually use the aforementioned TouchOfDeath, Ozzy manages to dodge it and get Thrax stuck, sealing the virus's fate.
* CoolShades: Owns a pair of these, and wears them frequently.
* DeadpanSnarker: Tends to make dry comments on the somewhat low quality of Frank's criminal underworld.
* DiseasedName: And a PunnyName at that, as his name is a play on the bacteria anthrax. This is a bit odd, however, considering that he is a virus and not a bacteria. It's possible that his name is purely for [[InNameOnly aesthetic]].
* DisneyVillainDeath: Subverted. He falls, but that doesn't kill him--it's what he falls ''into'' that does. [[FamilyUnfriendlyDeath And we get to see it.]]
* EstablishingCharacterMoment: The first thing he does upon being introduced is to [[KickTheDog casually murder two harmless workers]], [[FamilyUnfriendlyDeath at least one in an incredibly gruesome way]]. He then proceeds to [[WalkingWasteland burn their entire boat by merely scratching its surface with his index while he is walking]].
* EvenEvilHasStandards: Is visibly disturbed upon seeing some of Frank's nightmares and bad memories.
--> '''Thrax''': (after escaping from the room) This cat was sick before I even got here!
* EvilIsBurningHot: Thrax's immolating TouchOfDeath takes the form of one of his talons [[HotBlade glowing red hot]]. His plan to kill Frank involves sabotaging his hypothalamus, which is the gland responsible (among other things) for regulating body temperature. One Thrax steals an important component of the hypothalamus, the temperature skyrockets and deadly fires start breaking out across the city.
-->'''Thrax:''' "About time somebody turned up the heat in here!"
* EvilIsPetty: Only partially. Thrax wants to kill Frank in a record time so he can be in medical textbooks.
* EvilSoundsDeep: Fishburne's baritone voice plays this trope straight with Thrax.
* {{Expy}}: Given his color scheme and extremely short action timespan, he's one of Edgar Allan Poe's Red Death from ''The Masque of the Red Death''. This is given a nod via a witness calling him "''La Muerte Roja''".
* FameThroughInfamy: He hopes that his murders will put him in the medical textbooks.
* FamilyUnfriendlyDeath:
** His TouchOfDeath has pretty gruesome results, and one of the first things he does is inflict this on an innocent cell. Said victim proceeds to boil alive from the inside out.
** Fittingly, this ends up being Thrax's own fate; he falls into a glass of alcohol and is completely incinerated.
* FauxAffablyEvil: He likes to hum "Fever" by Peggy Lee and presents himself as charismatic, but this barely hides the monster he is.
* FingerPokeOfDoom: Quite literally with his first victim. "Ow."
* GloryHound: Thrax is like a serial killer who's trying to become famous in the most brutal fashion.
* KnightOfCerebus: Were you expecting a movie about Chris Rock as a blood cell to have a virus in the form of a serial killer?
* LackOfEmpathy: He makes everyone's suffering without any redeeming qualities whatsoever.
* {{Leitmotif}}: "Fever" by Peggy Lee, though it's invoked because he's always humming it. The title alone suits him.
* MonstrousGerms: He is a red-skinned humanoid with tentacle-like dreadlocks and a large burning claw on one of his hands.
* NamesToRunAwayFromReallyFast: Thrax, meant to evoke ''an''thrax.
* NiceJobFixingItVillain: In the final battle with Ozzy, he use the black chain holding the hypothalamus chromosome to try and choke him. But then Shane blinks, separating the two with the chain still around Ozzy's neck. His final attack failing thanks to Ozzy's morphing abilities seal the deal.
* OmnicidalManiac: Thrax's plans involve killing people, causing the civilizations of cells in their bodies to die. The loss of life is apocalyptic at the cellular level, with an implied decimation among humans (since Thrax wants his own chapter in the medical books he'd likely seek to become an epidemic, which would entail massive loss of life).
* PlayingWithFire: His fingernail claw burns whatever he scratches into a melting, burning lava mess.
* RedAndBlackAndEvilAllOver: Red-skinned, dressed in black, and ''definitely'' evil.
* {{Sadist}}: He revels in the pain he causes and enjoys to see his victims' suffering.
* ScaryBlackMan: Only in voice (Creator/LaurenceFishburne does it).
* SerialKiller: He keeps trophies from his victims and reminisces about them.
* ASinisterClue: Only a given, since that's the hand he uses to kill all his victims and spread his infection.
* SlasherSmile: He sports quite a few throughout the movie, the [[NightmareFace most notable one]] being when he threatens to kill Frank's daughter.
* SoftSpokenSadist: He likes to keep a low tone at times.
* TheSociopath: He'll kill as many people as it takes to get into the medical books.
* TouchOfDeath: His left index finger causes ''any'' organic matter it touches to combust or explode.
* VileVillainSaccharineShow: And ''how''. Apart from the serial killer overtones, there's his meeting the group of germs in the Zit. With the plan to organize coordinated assaults with the intention of causing widespread death and destruction, also spreading fear and intimidation outside Frank. Thrax comes across as a leader of a terrorist group planning an attack. It's jarring how such a vicious, murdering villain managed to stick in an otherwise light-hearted comedy.
* VillainousCheekbones: Thrax's cheekbones are so pointy they look sharp, and he his clearly evil.
* WouldHurtAChild: Brags about killing a little girl - and has his sights on Frank's daughter when he's done with Frank.

[[folder:Mayor Phlegmming]]
->'''Voiced by:''' Creator/WilliamShatner
* FatIdiot: He clearly doesn't see what could happen if he keeps giving Frank junk food instead of healthy food, hence the obesity.
* HateSink: As he is designed to represent and justify Frank's poor health, he inevitably ventures into this. Notably, he abolishes Ozzy from the police force for making Frank throw up even though it was an emergency situation, fails to acknowledge Thrax as a threat despite the fact that he had killed others in the past (dismissing him as the common cold when he was one of the deadliest viruses ever), and is the only one that doesn't see the problem in giving Frank nothing but junk food (and is oblivious to how it's straining Frank's relationship with Shane).
* {{Jerkass}} : He certainly is, especially to Ozzy.
* LaserGuidedKarma: Abolished Ozzy for having Frank throw up to get out an evil virus. Then at the end when he's been booted out of office, he presses a similar button and winds up flushing himself right out of Frank's own body.
* MayorPain: Though he's not corrupt per se, he's VERY incompetent at his job and cares more about his election than anything else.
* MyGodWhatHaveIDone: Doesn't say it but his reaction as the city of Frank burns down around him pretty much has this trope all over it.
* ObstructiveBureaucrat: Let's see, he fired Osmosis and gets Drix out of Frank just for ''popping a pimple without permit'' (Which is like blowing up a building in the real world) and as mayor control's nearly all of Frank's actions, including his slovenly behavior. Said neglect needless to say, almost ends up killing the guy and every cell with him.
* SleazyPolitician: To the tee.
* TooDumbToLive: His actions almost get his city destroyed.

[[folder:Leah Estrogen]]
->'''Voiced by:''' [[Music/{{Brandy}} Brandy Norwood]]
* TheChick
* GracefulLadiesLikePurple: Her suit and even her body are both purple.
* LivingMacGuffin: Is taken hostage by Thrax, and very nearly killed by him.
* NonMammalMammaries
* OfficeLady: Works as a secretary for Mayor Phlegmming.
* OfficialCouple: With Ozzy in the end.
* SassyBlackWoman
* ShesGotLegs: That mini-skirt isn't helping the fact that she has long legs.
* TheSmurfettePrinciple: Although Leah isn't the only female anthropomorphic cell in Frank's body, she's the only one with NominalImportance.
* {{Tsundere}}: Type B.
* WomenAreWiser

->'''Voiced by''': David Ossman
* AllThereInTheManual: His name was seen in tie-in media.
* AssholeVictim: Scabies whom Thrax made short work (and short pieces) of. Also, all his germ minions.
* BigBad: He is [[spoiler: until Thrax killed him.]]
* BullyingADragon: Scabies didn't like Thrax's bragging and compared him to Ebola.
* DiseasedName: Scabies is named after the itching condition, but is never shown to cause it besides living in the armpit.
* FamilyUnfriendlyDeath: [[spoiler: He was killed by Thrax.]]
* NoCelebritiesWereHarmed: Scabies' mannerisms and voice were based on Creator/MarlonBrando from Film/TheGodfather.
* StarterVillain: Of the film.
* TooDumbToLive: [[spoiler: He was surprised by Thrax's sudden attacks.]]

[[folder:Bruiser and Joe Cramp]]
* AllThereInTheManual: Joe Cramp's name is revealed through an unfinished tie-in action figure.
* EvilSoundsDeep: Bruiser has a pretty deep, gruff voice.
* MeaningfulName: Bruiser has four arms and is quite tough, for a germ.
* ThoseTwoBadGuys: To Scabies and [[spoiler: Thrax.]]

[[folder:Francis "Frank" [=DeTorre=]]]
->'''Played by:''' Creator/BillMurray
* BumblingDad: He means well, and does care about Shane, but he has a major selfish streak. Though this is mostly due to Mayor Phlegmming overriding his body for his own ends.
* ChildrenRaiseYou
* FantasticVoyagePlot: The plot takes place inside Frank's body
* FatIdiot
* GuysAreSlobs: Played straight and subverted, as in a flashback we hear Shane complain that neither he or Maggie, his wife, take care of themselves very well, Frank just got worse after Maggie died.
* TheMourningAfter: Still mourning the loss of his wife, Maggie. Justified, as it seems to be [[TooSoon a relatively recent loss]].
* OneOfTheKids
* PermaStubble
* StrawLoser
* TooDumbToLive: What kicks off the whole plot as he ''eats an egg that was inside the mouth of a monkey and got spat out onto the ground.'' [[SarcasmMode Yeah, that seems sanitary]].
* VomitIndiscretionShot: Double Subverted; we don't see it actually happen (although we hear him retching, the focus is on the horrified crowd at the science fair), but we do see a picture of him puking all over Shane's teacher.

[[folder:Shane [=DeTorre=]]]
->'''Played by:''' Elena Franklin
* BrokenBird
* CallingTheOldManOut: Blames Frank and his unhealthy habits for Maggie's untimely death, and calls him out for deciding to take her to a chicken wing FanConvention instead of the hiking trip she was looking forward to.
* ChildrenRaiseYou: Takes care of her dad, because he doesn't take care of himself.
* GenderBlenderName: Her first name is predominantly used by boys.
* MissingMom: Her mom died of an unspecified illness. Though it's implied she was as unhealthy as Frank has been throughout the movie.
* OnlySaneWoman: Shane often has to be the adult between her and her father.
* WomenAreWiser