!Main characters

!!Osmosis "Ozzy" Jones
->'''Voiced by:''' Creator/ChrisRock
* {{Badass}}
* CoolCar: Had his cop car customized.
* CowboyCop
* DoggedNiceGuy: Has trouble winning Leah Estrogen's affections. [[spoiler: He does at the end, though.]]
* {{Determinator}}
* TheHero
* 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
* RedOniBlueOni: The red to Drix's blue.
* SensitiveGuyAndManlyMan: The Manly Man to Drix's Sensitive Guy.
* SesquipedalianSmith
* ShapeshifterShowdown: What saves him against Thrax.

!!Drix
->'''Voiced by:''' David Hyde Pierce
* ArmCannon
* {{Badass}}
* TheBigGuy
* ButNotTooWhite: Drix is played by David Hyde Pierce. The producers were ''looking'' for someone as white-bread as possible. [[Series/{{Frasier}} Niles Crane]] is about as white-bread as you can get.
* ByTheBookCop
* CaptainErsatz: Drix bears a strong resemblance to ComicBook/IronMan.
* GeniusBruiser
* AnIcePerson
* 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.
* TheSmartGuy

!Movie characters

!!Thrax
->'''Voiced by:''' Creator/LaurenceFishburne
* BadassLongcoat
* BigBad
* DeadpanSnarker
* EvilIsPetty: Only partially. Thrax wants to kill Frank in a record time so he can be in medical textbooks.
* FamilyUnfriendlyDeath: He falls into a vat of alcohol, which of course has very deadly effects on germs... although to be fair this tends to be how irredeemable villains tend to die...
** Also applies to the first cell he kills. What he does to the bacteria mob boss too, though to a lesser degree.
* FauxAffablyEvil
* GloryHound: See EvilIsPetty. Thrax is like a serial killer who's trying to become famous in the most brutal fashion.
* 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
* KillItWithFire[=/=]PlayingWithFire: His finger-nail claw pretty much burns whatever he scratches to a melting, burning lava mess.
* KnightOfCerebus
* ScaryBlackMan: Only in voice (Creator/LaurenceFishburne does it).
* SerialKiller: He keeps trophies from his victims and reminisces about them.
* VileVillainSaccharineShow
* VillainousCheekbones
* WalkingWasteland: His left index finger causes ''any'' organic matter it touches to combust or explode.

!!Mayor Phlemming
->'''Voiced by:''' WilliamShatner
* FatIdiot
* {{Jerkass}}
* 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: Type B.
* 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


!!Leah Estrogen
->'''Voiced by:''' 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 Phlegming.
* OfficialCouple: With Ozzy in the end.
* SassyBlackWoman
* 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

!!Francis "Frank" [=DiTorre=]
->'''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 Phlemming 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.

!!Shane [=DiTorre=]
->'''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.
* DeceasedParentsAreTheBest: Averted; she misses her mom a lot, and is rather distant from the other kids at school. Taking care of her dad doesn't help either.
* GenderBlenderName
* MissingMom: Her mom died of an unspecified illness. Though it's implied she was as unhealthy as Frank has been throughout the movie.
* OnlySaneMan: Female version.
* WomenAreWiser