!!Milo James Thatch

->'''Voiced by''': MichaelJFox

* {{Adorkable}}: One of the reasons the fangirls adore him.
* BadassBookworm: Milo [[TookALevelInBadass becomes this]] during the last action sequence.
* BowTiesAreCool
* ButtMonkey: At least until he TookALevelInBadass, [[BadassBookworm saved Atlantis]], and got the girl.
* CunningLinguist
* [[spoiler:GoingNative]]: [[spoiler:At the end of the film.]]
* HiddenDepths: He's an eager but put-upon linguist and cartographer... who also knows an awful lot about boilers, right down to how to treat certain brands and models.
* KindheartedCatLover: Milo has a white Persian named "Fluffy."
* [[ABoyAndHisX A Man And His Cat]]: Prior to the film's adventure, he lived alone in an apartment with his pet cat.
** [[ABoyAndHisX A Man And His Lava Dog]]: In the sequel Milo and Kida own a lava dog named Oggie.
* MayflyDecemberRomance: With [[Really700YearsOld Kida]].
* {{Megane}}
* MightyWhitey
* NaiveNewcomer
* TheNavigator: Due to being the only one who can translate the Shepherd's Journal, though he does occasionally get it wrong.
* OfficialCouple: With Kida. It's downplayed, though.
* RaisedByGrandparents: After his parents died, his Grandfather raised him.
* ScienceHero
* TookALevelInBadass

!!Kidagakash Nedakh

[[quoteright:350:http://static.tvtropes.org/pmwiki/pub/images/Kida_9125.png]]
[[caption-width-right:350:''"Our way of life is dying."'']]
->'''Voiced by''': Creator/CreeSummer

* AmbiguouslyBrown
* BadassPrincess: In a brief yet oh-so-satisfying action scene in which she [[GroinAttack knees a guy in the crotch]], bashes another with the butt of a rifle while trying to wrench it free from its owner, and knocks another soldier to the ground while drawing her knife. Even better considering she showcases skills as a hunter/gatherer.
* BareYourMidriff
* TheChiefsDaughter
* [[spoiler: CoolCrown: Her tiara at the end of the film.]]
* DarkSkinnedBlonde
* DeadlyUpgrade: [[spoiler:The crystal, which preserves the life of Atlantis, will merge with a royal host if it senses danger. Since Rourke is threatening it, it merges with Kida, putting her into a vegetative state that will kill her if she is in it too long, as it did to her mother when Atlantis first sank.]]
* DoesNotLikeShoes
* FauxActionGirl: ExecutiveMeddling made her into this, unfortunately. Fortunately, [[{{Xenafication}} she gets better]] in the sequel.
* GiveGeeksAChance: Her dynamic with Milo, obviously.
* [[spoiler:TheHighQueen]]: [[spoiler:After she follows into her father's footsteps at the end of the film, with Milo as her HotConsort.]]
* InSeriesNickname: Her full name is is hard to say, so she goes by "Kida".
* MacGuffinGirl: [[spoiler:Once she merges with the Atlantean crystal.]]
* MayflyDecemberRomance: With Milo, who only has lived a very small part of her lifetime.
* MissingMom: Kida's mom was exposed to the crystal's power for too long and died as a result. She is briefly seen in a {{flashback}}.
* MsFanservice
* MysticalWhiteHair: White hair seems to be a racial trait of all Atlanteans, suggestive of their longevity (but not their age—the children have white hair, too).
* NubileSavage
* OfficialCouple: With Milo. It's downplayed, though.
* {{Omniglot}}: Because according to her, all modern languages descend from Atlantean, she can speak English perfectly as well as French and of course Atlantean, and pretty much anything else you throw at her.
* SuperNotDrowningSkills: She can't ''breathe'' underwater, but is still an amazing diver. Justified in where she's from.
* ReallySevenHundredYearsOld: She's 8,800 years old.
-->'''Milo''': Oh well, looking good!
* RoyalsWhoActuallyDoSomething
* TheUnpronounceable: Milo shortens her name to "Kida."
* TomboyPrincess
* TragicKeepsake: [[spoiler:The bracelet that her mother inadvertently took with her as she was pulled into the Heart Of Atlantis.]]
* WalkOnWater: As the Heart of Atlantis beckons to her.

!!Lyle Tiberius Rourke

->''"I love it when I win."''\\
'''Voiced by:''' [[TheGreatEscape James]] [[Series/{{Maverick}} Garner]]

* AxCrazy
* AnAxeToGrind
* BigBad
* ClippedWingAngel
* ColonelBadass
* CrazyPrepared: According to Audrey, Rourke is "never surprised" and "carries a lot of guns." Both of which are slight {{understatement}}s.
* EvilAllAlong
* [[spoiler:FamilyUnfriendlyDeath: After transforming into crystal because of being jabbed with it, he is literally shattered by the helicopter blades.]]
* FauxAffablyEvil: Even when he throws [[spoiler:[[TheDragon Helga]]]] off the helicopter, he calls cheerfully, "Nothing personal!"
* GasMaskMooks: His henchmen.
* HoistByHisOwnPetard: [[spoiler:Tossing Helga off the copter to lighten the load was what really messes up his plans]].
* [[spoiler:LiterallyShatteredLives: Rourke's fate.]]
* InsistentTerminology: [[spoiler:"Mercenary? I prefer the term 'adventure capitalist'."]]
* OnlyInItForTheMoney
* PlayingAgainstType: James Garner's best known roles are people who are basically on the side of right (Bret Maverick, Jim Rockford). Not this time.
* PlotBasedPhotographObfuscation
* SlasherSmile
* VillainousBreakdown: [[spoiler:As Milo ruins his attempt to carry the crystal containing Kida to the surface, Rourke starts attacking him with an axe]]:
-->"I consider myself an even-tempered man; it takes a heck of a lot to get under my skin. But congratulations--you just won the solid gold Kewpie doll!"
* ZeppelinsFromAnotherWorld

!!Helga Katrina Sinclair

->''"Well, I came down the chimney. Ho ho ho."''\\
'''Voiced by:''' [[Series/BabylonFive Claudia Christian]]

* BadassLongcoat: Briefly wears one.
* BlondesAreEvil
* BeautyMark
* DarkActionGirl
* [[spoiler:DisneyVillainDeath: Subverted. It wasn't the fall that killed her (although it quite possibly broke her back and/or caused quite a bit of internal bleeding), but having a flaming zeppelin crash on top of you would certainly do the trick.]]
* DeadpanSnarker
* TheDogBitesBack: It is [[spoiler:Helga's LastBreathBullet after Rourke betrays her]] that really foils the EvilPlan.
* TheDragon
* FemmeFatale
* FlareGun
* HeelFaceDoorSlam: [[spoiler:Helga shows some remorse when she discovers that they will be stealing from living people and not a long-dead civilization, but she is betrayed and mortally wounded by Rourke before she (possibly) switches sides]].
* [[spoiler:LastBreathBullet]]
* [[spoiler:NothingPersonal: Her FamousLastWords, doubling as an IronicEcho.]]
* RightHandCat: The standard white Persian, although it's actually Milo's.
* {{Sexophone}}: Heard when she makes her debut in Milo's apartment.
* [[spoiler:ThrownFromTheZeppelin]]

!!Audrey Ramirez

->''"Two for flinching!"''
->'''Voiced by:''' [[Film/SixDaysSevenNights Jacqueline Obradors]]

* ActionGirl
* DaddysGirl: Strongly implied; she wants to earn enough money from the expedition to open another shop for her father's business.
* DeadpanSnarker: Occasionally.
* DefrostingIceQueen: She's rather abrasive to [[NaiveNewcomer Milo]] at first, but once she warms up, she's quite a softie.
* NiceHat: One that manages, against all odds, to stay on her head for the entire film.
* SpicyLatina
* TeenGenius: The youngest member of the team, and an ace mechanic.
* WrenchWench

!! Vinny Santorini

->''"With something like that, I would have a white wine, I think."''-Vinny on the Leviathan
->'''Voiced by:''' Don Novello

* DeadpanSnarker: Very much so.
* DemolitionsExpert
* EvenEvilHasStandards
* HeelFaceTurn: Along with the rest of the group when Milo calls them out.
* HeroicComedicSociopath: Has some of the most violent lines in the movie. They're also some of the funniest.
* OnlyInItForTheMoney
* TheStoic: Most of the time, he has a very bored expression on his face. He only really smiles twice in the movie: after blowing up the pillar to make a bridge, and when [[spoiler:he discovers the explosive capabilities of the Atlantean flyers' {{Wave Motion Gun}}s]].
* StuffBlowingUp: Vinny loves explosions, but not enough to be a BombThrowingAnarchist.

!! Dr. Joshua Sweet

->'''Voiced by:''' Phil Morris

* ChekhovsGun: His saw, which he mentioned in the beginning and which he and Audrey later use to try and free the crystallized Kida.
* GentleGiant
* MeaningfulName: He is one of the friendliest and most decent members of the group, and the first to HeelFaceTurn (after Rourke attacks the Atlantean king).
* LastNameBasis
* MotorMouth
* NiceGuy: Mentioned by Milo when he's attempting to teach Kida the names of his teammates. Milo has some trouble making a distinction for her between the names "Sweet" and "Cookie" and that cookies are sweet and Sweet is a nice person.
* TeamDad: He is the wisest and most compassionate member of the group.
* TwoferTokenMinority: He's African-American and Native American.

!! Gaeton Moliere / "Mole"

->'''Voiced by:''' CoreyBurton

* TheFriendNobodyLikes: Everybody in the group is disgusted by him, and it says quite a lot that in a group that includes Cookie, Vinnie and Mrs. Packard that ''he'' is considered the biggest freak around.
* GeniusSlob: The Mole, dirt is his job and his hobby. Brilliant geologist. Can be threatened with soap.
* NiceHat: His is a leather cap.
* ThePigPen: To the degree where soap is a CoolAndUnusualPunishment.
* OnlyKnownByTheirNickname
* PunnyName
* SherlockScan: He tells Milo what breed his cat is and a bunch of other things merely by examining the dirt under his nails.
* YouDoNotWantToKnow: His {{backstory}}, according to Dr. Sweet, is this.

!! Jebediah "Cookie" Farnsworth

->'''Voiced by:''' Jim Varney

* CampCook
* TheDitz
-->I seen this in the Dakotas! They can smell fear just by looking at ya. So keep quiet.
* LethalChef: His cooking, thrown on the campfire, [[EverythingMakesAMushroom makes a mushroom cloud]] at one point.
* OnlyKnownByTheirNickname
----