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NeutralChao Render.png
First seen: Sonic Adventure (1998)
Species: Chao
Gender: N/A[1]
Height: Indeterminate[1]
Weight: Indeterminate[1]

Chao (チャオ) (pronounced /ˈtʃaʊ/, plural form also Chao) are relatively small, sentient creatures found in numerous Sonic the Hedgehog media, especially the video games. They serve as a way to introduce both artificial life (in the programming, not in the franchise's universe) as well as more plot to the franchise. They are based on earlier forms of the technology behind them, known as "A-Life", which appear in NiGHTS into Dreams with the Nightopians.

Chao have the ability to absorb and learn skills and traits from other lifeforms such as small animals, even altering their appearance, and their behaviour and personality are influenced by how they are raised. They are typically found in Chao Gardens, though they are also known to live in any location with fresh, clean water.[2]


Chao are based on a special technology called A-Life, which originally came from NiGHTS into Dreams on the Sega Saturn where it was used for the Nightopians. They looked like small elves (peach colored) with bald heads and little blue clothes. However, despite their lower IQ to chao, the Nightopians did have emotions which were reflected in the music they sang and the music in the stages. They could die and become cross-bred with stage enemies (creating things called Mepians), and were born from small white eggs similar to those of the birds.

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The Chao are descendants of an alien race only known as the Ancients, who are water-like beings that brought the Chaos Emeralds to Earth tens of thousands of years ago. Since their home world was destroyed by The End they were forced to stay on this planet. Living here for centuries caused them to change into a new species called the Chao.[3][4] Later one of the Chao was mutated into a god-like being named Chaos by the Master Emerald. He served as the guardian of the Emerald Shrine and the Chao until Pachacamac tried to take the Chaos Emeralds.[5]

Game appearances

Chao appear in the following Sonic games:


Possibly the most famous Chao is Cheese, the invincible partner of Cream the Rabbit (the walking, talking and flying rabbit) which can be seen in action in Sonic games (Namely Sonic Advance 2 and Sonic Heroes) as well as being a character in Sonic X, and a cameo in GameCube's Sonic Adventure DX, a remake of Sonic Adventure for the Dreamcast.

As with the Chao of earlier Sonic manga and magazines, Cheese retorts "Chao Chao Chao" instead of talking. This is said to be taking advantage of the Pokémon craze, but this is not true as many fictional Japanese animals said their name rather than talking long before Pokémon. However, this speech aspect is not true to all Chao, as Chao from the games often purred or make simple noises rather then simply saying their name.

Chao come in many forms, and the way they are raised has a large impact on their physical appearance and emotional growth. There are however a few 'basic' forms of chao that can be achieved through selective breeding. These too are divided into two groups: alignment and attributes.

Raising Chao

Sonic checking a Chao's stats in Sonic Adventure DX.

Chao have an assortment of stats that can affect their performance in the garden as well as in mini-games. Each stat is graded from E-S, with E being the worst and S being the best, and the quality of the grade affects how much a particular stat will grow when leveling up (to a maximum of Lv.99). There are five visible stats, as well as two hidden stats (marked in italics):

  • Swim: The Chao's swimming capability. At a low level, the Chao cannot swim and will struggle in water.
  • Fly: The Chao's flying capability, affecting how far it'll go after jumping off a ledge.
  • Run: The Chao's running capability. At first, the Chao will crawl on the ground, but as this stat increases it will begin to walk on two feet and eventually take bigger steps.
  • Power: The Chao's physical strength. This stat is necessary for climbing walls and shaking trees.
  • Stamina: The Chao's overall stamina. At low stamina, the Chao's performance drops significantly.
  • Intelligence: Affects how quickly the Chao will solve puzzles during Chao Races.
  • Luck: This affects how often the Chao will trip over as well as how it will pass certain obstacles.

Chao can be trained with Chaos Drives from G.U.N. robot enemies in Action Stages, or animals either found out in the open or inside various Badniks made by Dr. Eggman. Red represents power, Green represents speed, Yellow represents swimming and Purple represents flying. (Getting the Drives could also be done by trading them for Rings in Sonic Adventure 2: Battle.) Animals can also affect their appearance; for instance, rabbits can give Chao rabbit ears. Various fruits can be bought either in-game (like in Sonic Adventure 2: Battle), in Chao Adventure, or in the Tiny Chao Garden that serve a similar purpose. Plus, in the first Sonic Adventure, feeding the nuts found on the trees gives Chao different stats, but it depends on who the player plays as (for instance, Sonic raises their speed, Tails raises their flight, Big raises their swim... the only one who has no effect is Gamma).

Stamina is not increased by animals or Chaos Drives, only by food, such as the fruit growing in the Chao Garden. The Chao Fruit from the Black Market, as well as the fruits obtained in the Tiny Chao Garden, can raise other stats. Intelligence and Luck are both increased by 20% by all animals.


Chao begin life in a neutral alignment. During their first stage of life, their later development is determined on how they are treated. They can, after they evolve, become either a Hero Chao or a Dark Chao. In Sonic Adventure DX, alignment is altered based on special foods given to the Chao. In Sonic Adventure 2, being good to the Chao, such as picking them up, rocking them, and petting them, will make the Chao favor the alignment of the character that is doing the action. Sonic, Tails, and Knuckles are the Hero characters in the game, while Shadow, Rouge, and Dr. Eggman are the Dark characters. Harming the Chao, via throwing them, stepping on them, or actively attacking them, makes them favor the opposite alignment of the character, though being good with the opposite alignment works just as well.


Chao life-cycle chart.

Chao begin life in an egg, similar to many animals in the real world (particularly non-mammals). When they hatch, they can be trained in many different ways, having multiple different attributes and emotional states. The Chao from Sonic Adventure 2 can also favor "dark" and "hero" sides which can lead to variations in visual evolution. Depending on the game, they take various times to evolve, though it usually takes about 3 real-time hours, which equates to about 1 Chao year. When evolving, they go into a cocoon state (similar to their normal egg state) for a small amount of time, then emerge in an adult form. Depending on how much they are raised in a specific stat based on what the player gives them, they will become a particular type (e.g. Fly-type if the player focused on raising its flying stat). As the Chao grows older from then on, they will evolve further, again based on what the player gives to them, though these changes slowly happen on the fly without going into a cocoon.

Eventually, a Chao will reach the end of its lifespan of about 5 Chao years which, in Sonic Adventure 2, will take about 8-20 hours spent in a Chao Garden. When this happens, they'll go into another cocoon state before they either die or reincarnate (depending on how the player treats them). If the Chao has lived a happy life, the cocoon will be pink and the Chao will transform back into an egg, allowing them to be reborn while retaining their stat grades, skills, tools, rewards and intelligence; the Chao's stat levels return to Lv.1 and they will only retain 10% of their total stats prior to the end of their life. They can reincarnate as many times as possible, allowing the player to effectively max out all of their stats with enough patience. If they have been ignored or abused during their life, they will go into a grey cocoon and disappear forever. In the Dreamcast versions (as well as the Steam version of SADX due to a bug), the cocoons always appear white.

Chao can also be trained to "ultimate forms" such as the Chaos Chao, the Devil Chao and the Angel Chao after they have reincarnated twice, and have been given one of every animal in the game during the childhood stage of their third life onwards. The three variations are all immortal, but do not have the ability to mate and make more Chao.


2 Chao have created an egg after mating.

Once a Chao has evolved into an adult, it gains the ability to reproduce. Chao have no gender, therefore they can mate with any adult Chao. When a Chao is ready to reproduce, it will sit down in a ring of flowers with a heart over its head. Typically, this will happen naturally twice in a Chao's lifespan, though the player can force a Chao to mate by feeding it a 'Lifenut' from the Chao Adventure VMU minigame in Sonic Adventure and Sonic Adventure 2, or a 'Heart Fruit' from the Black Market in Sonic Adventure 2: Battle and Sonic Adventure DX. For two Chao to mate, one of them has to be ready to mate, and the other has to be close to mating. If the two Chao are ready to mate when they are placed together in the circle, they will perform a courtship dance and make a new egg appear. Chao also may breed when connecting two VMUs together.

The offspring Chao inherits statistics and other traits of the parents, and if the parents have specific physical traits, then the child can end up being an unusual type of Chao such as a two-tone Chao or a transparent Chao. Most Chao are compatible with breeding; a Hero Chao can even breed with a Dark Chao. As mentioned above, Chaos Chao cannot breed, neither can certain special event Chao.


The way a Chao will behave is heavily influenced by how well the player treats it with specific characters. If a Chao has been pet, fed and generally taken good care of, they will grow affectionate towards the character that treated them well. They will occasionally approach the character and nuzzle up to them sometimes, and will even stop what they're doing and come to the character happily whenever they whistle. They will also express happiness whenever the character they like is holding them.

On the other hand, the player can choose to abuse the Chao by starving it, leaving it in water if it cannot swim, and even attacking and throwing the Chao. This will gradually cause the Chao to become fearful of the character who abused them, quivering in fear or crying, and will even struggle when being held by the character. Depending on a Chao's personality type, it will do different things if it has been particularly abused, which include running away in terror from the character, attempting to attack the character in retaliation (though their attacks are harmless), or simply crying. A player may choose to do nothing but abuse Chao for personal enjoyment, or if it's in their benefit, such as abusing it with a character of the opposite alignment (e.g. abusing it as Tails to turn it into a Dark Chao, and vice versa), or to remove a hat that the Chao is wearing. Sometimes, players can hurt Chao by accident.

Abusing a Chao will decrease its lifespan and potentially cause it to die by the end of its lifespan. In the Dreamcast version of Sonic Adventure, Chao are very fragile, meaning it is possible for a Chao to die immediately if they are attacked too much. This was later removed in later games and ports with the introduction of the Hero/Dark aspects, so repeatedly attacking a Chao will simply change its personality and make them hate the player (though they will still eventually die after adulthood).

In Sonic Chronicles

In Sonic Chronicles: The Dark Brotherhood, Chao eggs can be found scattered throughout the game, from Green Hill Zone to the Nocturne fortress. Chao hatch from these eggs over time, and are deposited in the "Chao Garden" (which is not an actual accessible location as in the Sonic Adventure games, but can be viewed from the game menu).

The various Chao which hatch have profound usefulness in the game's combat system. Equipping a fighting character with a chao confers a variety of different combat advantages.

List of Sonic Chronicles Chao

There are 45 different Chao in all, five of which (the "Viral" Chao) could not be accessed with through conventional play. These five "Viral" Chao were supposed to be unlocked at special Sega events - which were later apparently canceled. Multiple copies of each of the 45 Chao can be collected. (Note: The descriptions for the Viral Chao were presumably not given to beta testers and as a result not checked over. Though they work, 3 of them have descriptions that are longer than the game can display. The full descriptions found in the ROM image are listed for those.)

Name Rarity Appearance Effects
Baki Viral* Ninja-style black with a black head-orb and pink face Bonded character making a successful counter move will automatically get free attacks against the enemy.
Barbo Common Dark blue with red/white extremities and a green head-orb Increases Maximum HP of bonded character.
Belgog Rare Blue with light blue extremities and a pink head-orb Bonded character is much harder to hit.
Bepke Rare Black/white with white horns and a red head-orb One enemy will automatically attack the bonded character instead of other team members.
Blayze Rare Light grey with brown extremities and a red head-orb Bonded character does much more damage in battle.
Bobo Rare Black/magenta with magenta horns and a yellow head-orb Bonded character will always find an extra reward item after combat.
Cheese Unique** Cream's best friend in the whole wide world: Light blue with a red bow and yellow head-orb Greatly increases the luck of all team members.
Cheezlet Common Light blue with white extremities and a yellow head-orb Bonded character does more damage in battle.
Choo Common White with magenta extremities and a pink head-orb Bonded character regenerates PP at the start of each combat round.
Choopaloo Unique Orange with horn-like ears, purple extremities, and a light blue head-orb Increases XP gained from each battle.
Churdle Common Aquamarine with light blue extremities and a pink head-orb Bonded character has a better chance of hitting targets in battle.
Dusty Rare Purple/yellow with blue extremities and a blue head-orb Increases the chance that the team will catch a fleeing opponent.
Farfinkle Viral* Ninja-style black with a black head-orb and orange face Bonded character automatically inflicts a random status effect on enemy when making a normal attack.
Ferox Unique Green with a grey muzzle, aquamarine extremities, and a red head-orb Bonded character automaticly succeeds using their POW moves.
Fess Rare Black/blue with blue horns and a light blue head-orb Increases the odds that Chao eggs will hatch rare or unique Chao.
Fimbley Viral* Ninja-style black with a black head-orb and blue face Bonded character will automatically be missed some basic attacks each round.
Ghise Common Dark blue with pale blue extremities and a light blue head-orb Bonded character's attacks do Water damage.
Gibber Rare Purple with blue extremities and a pale blue head-orb Bonded character has greatly increased resistance to damage.
Griff Common Pale blue with brown extremities and a gold head-orb Bonded character's attacks do Ice damage.
Hayda Rare Dark green with a black stomach and a scarlet head-orb Regenerates PP at the start of each combat round for all team members.
Jirna Common Yellow with grey extremities and a purple head-orb Chao creates an earth shield to protect against damage.
Joy Rare Pink with scarlet extremities and a blue head-orb Regenerates HP at the start of each combat round for all team members.
Kayla Rare Red/black with red horns and a green head-orb Reduces the team's chance of being ambushed.
Keroyo Rare Green with light green extremities and a yellow head-orb Increases odds of enemies fleeing from battle.
Knickt Common Gold with pale yellow extremities and a blue head-orb Chao creates a shield of lightning to protect against damage.
Koolet Common Pink with pale purple extremities and a light blue head-orb Bonded character is harder to hit.
Korus Common Orange with ochre extremities and a black head-orb Chao creates a shield of fire to protect against damage.
Luunan Rare Pale yellow with an orange stomach, turquoise extremities, and a blue head-orb Greatly increases the maximum PP of bonded character.
Oldarg Rare Red with a white stomach, scarlet extremities, and a dark green head-orb Bonded character has a greatly increased chance to hit targets in battle.
Oolean Common Pale yellow with white extremities and a dark blue head-orb Increases maximum PP of bonded character.
Ovus Unique Yellow with orange extremities, white stomach, and a magenta head-orb Bonded character is automatically revived once during a battle.
Perty Common Dark green with light green extremities and a red head-orb Chao creates a shield of water to protect against damage.
Pooki Viral* Ninja-style black with a black head-orb and red face Bonded character takes less damage from enemy attacks and spreads the remaining damage evenly among other team members.
Pyraz Common Red with white extremities and a blue head-orb Bonded character's attacks do fire damage.
Radu Rare Light blue with blue extremities, yellow stomach, and a black head-orb Greatly increases the maximum HP of bonded character.
Rugle Common Pale pink with ochre extremities and a green head-orb Bonded character has increased luck.
Seeri Common Purple with aquamarine extremities and a dark green head-orb Chao creates a shield of wind to protect against damage.
Seggo Common Yellow with brown extremities and a purple head-orb Bonded character's attacks do Wind damage.
Spartoi Unique Purple with mauve, cog-like facial markings, golden eyes, and a yellow head-orb Bonded character's attacks may cause instant KO against enemies.
Stebsly Common Black with blue extremities and a pink head-orb Bonded character regenerates HP at the start of every combat round.
Stilgin Common Red with dark red extremities and a white head-orb Bonded character's attacks do Earth damage.
Stugs Viral* Ninja-style black with a black head-orb and white face Bonded character is avoided by enemy attacks except as last surviving target.
Velk Common Light purple with pale blue extremities and a blue head-orb Bonded character has increased resistance to damage.
Zimba Common Grey with pale orange extremities and a purple head-orb Bonded character's attacks do Lightning damage.
Zousar Rare Yellow with pale blue extremities and a pale dirt-brown head-orb Increases the team's chances of Ambushing opposing teams.
  • * Referred to as Unique in game.
  • ** Cheese is even more unique than the other "unique" chao in The Dark Brotherhood; s/he can't be hatched from a Chao egg, and must instead be picked up in Green Hill Zone as part of the mission to recruit Cream.
  • In the Japanese version of the game, four of the viral chao can be unlocked by entering a cheat code in the Chao Garden.
  • For Western players, Stugs is the only viral chao for whom the release event was actually held. The only way to acquire the other viral chao is through savestate manipulation or Action Replay cheats. When unlocked, several of their descriptions are apparently longer than the game can display.

Character Chao

Some Sega characters have had their appearance used for the basis for Chao with a specific raised stat and alignment.

  • A Neutral Chao with a raised Run stat resembles Sonic.
  • A Dark Chao with a raised Run stat resembles Shadow.
  • A Neutral Chao with a raised Fly stat resembles NiGHTS.
  • A Neutral Chao who has regenerated twice, then evolved again after contacting all animals at least once, becomes a Light Chaos Chao. This Chao resembles Chaos.
  • A Chao resembling Tails can be obtained through the GameCube version of the game Phantasy Star Online Episode I & II, and through the Sonic Team Joy Carry Collection on the Nintendo GameCube Soft e-Catalog Summer 2003 disc.
  • Chao resembling Knuckles and Amy can also be obtained through the Sonic Team Joy Carry Collection on the Nintendo GameCube Soft e-Catalog Summer 2003 disc, and were attainable through a special Sega event.
  • The Chao that hatch and look similar to the common coloring (those that are similar to Cheese) they will have a crest on them and is in the EXACT same area that closely resembles Knuckles no matter what type of Chao they are.

In other media

Sonic X

Chao appear as a species native to Sonic's world and Earth in the Sonic X anime series and its comic series. In the 22nd episode, Little Chao Lost, Chris and company discover a secret Chao Garden full of wild Chao. Only Neutral Chao appear in the anime series, though the comics have featured a Dark Chao.

Sonic the Hedgehog (Archie comics)

In the Sonic the Hedgehog comic series and spin-offs from Archie Comics, Chao appeared as a species native to Mobius and the offspring of Chaos. After the main cast encountered the Chao after the incident with Chaos, they slowly moved into New Mobotropolis. After the events of Worlds Collide, the Chao became identical to their video game counterparts.

Sonic the Hedgehog (IDW comics)

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Characters in the Sonic the Hedgehog game series
Recurring characters
Heroes Sonic (Super, Starfall, Hyper, Darkspine, the Werehog, Excalibur) | Tails (Super) | Knuckles (Super, Hyper) | Amy (Super, Hyper) | Mighty (Super) | Ray (Super) | Espio | Charmy | Vector | Cream | Big | Blaze (Burning) | Silver (Super) | Sticks
Anti-heroes/Neutrals Shadow (Hero, Dark, Super) | Rouge | E-102 Gamma | E-123 Omega | Jet | Wave | Storm
Villains Dr. Eggman | Metal Sonic (Rocket, Neo, 3.0) | Mecha Sonic (8-bit, Mk. II, Mk. III, Super) | Fang | Tails Doll | Metal Knuckles | Chaos (Perfect) | E-Series | ZERO | Biolizard (Finalhazard) | Black Doom (Devil Doom) | Eggman Nega | Orbot | Cubot | Deadly Six (Zavok, Zazz, Zomom, Master Zik, Zeena, Zor)
Teams Sonic/Heroes | Rose | Dark | Chaotix | Babylon
Other Animals (Flicky) | Froggy | Chao (Hero, Dark) | Tikal | Pachacamac | Omochao | Chaclon | Gerald & Maria Robotnik | President | King Boom Boo | Cheese | Chocola | Vanilla | G.U.N. Commander | Wisps | Mother Wisp
One-off characters
Heroes Emerl | Marine | Lumina Flowlight | Chip | Shahra | Knights of the Round Table | Caliburn | Yacker | Avatar | Barry | Trip (Super)
Anti-heroes/Neutrals Bean | Bark | Shade | Merlina | Sage
Villains Witchcart | Hocke-Wulf | Bearenger | Carrotia | Battle Kukku Army (15th, 16th, Dr. Fukurokov) | E-101 Beta | Void | Chaos Gamma | Gemerl | Shugo-hei | Iblis | Mephiles | Solaris | Erazor Djinn | Captain Whisker | Johnny | Master Core: ABIS | Ix (Super) | Dark Gaia | King Arthur | Hard Boiled Heavies | Infinite | The End | Mirage Express
Teams Vector | Eggman
Other Birdie | Illumina | Secretary | Elise | Duke of Soleanna | Sonic Man | Coconut Crew | Vikings | Professor Pickle | Wentos | Don Fachio | Dodon Pa | Koco | Ancients | Conductor | Conductor's wife | Ariem | Heavy | Bomb | Tiara Boobowski | Honey