Chaos is a Chao that mutated into a water elemental, which was responsible for all but wiping out the Knuckles Tribe of Echidnas. Imprisoned in the Master Emerald by Tikal, a girl from that tribe, Chaos remained trapped for centuries until he was released by the maniacal Dr. Eggman. After accumulating power from various Chaos Emeralds, he attacked Station Square only to be stopped by Super Sonic. Following this, Chaos and Tikal returned to their home within the Master Emerald.
Awoken by Eggman
After discovering the legend of the Chaos, the beast was awoken by Dr. Eggman after the scientist shattered the Master Emerald. The Doctor used Chaos in his plan to destroy Station Square, hunting down Chaos Emeralds to help Chaos grow in strength and size. However, it eventually turned against it's master and, in it's Perfect form, ravaged the city itself with a devastating flood. The beasts rampage was put to an end by Super Sonic. Reduced back to its base form, it returned to it's home inside the Master Emerald. (SA/SADX)
Merged with a Devil
- See also: Chaos Devil
Sometime after, the world was rewritten by the second Genesis Wave. This created an altered timeline in which Chaos had been previously pitted against Sonic, who, a lot like before, successfully defeated the former with the help of Tikal. Much later, Chaos was reawakened again by Dr. Eggman and was merged with Dr. Wily's Devil Core to create the Chaos Devil. The monster was accidentally unleashed by Rouge the Bat aboard the Wily Egg during her attempts to bring down the ship from within. It managed to capture Rouge and Metal Sonic and was menaced by Bass, but the two doctors arrived and ordered it to release its captives. It did so, and Rouge was taken away to be roboticized, while the doctors prided themselves on the success of the Chaos Devil's operation. It later appeared again to engage Sonic and Mega Man as they made their way deeper into the Wily Egg, but was engaged by the heroic robot Duo. After a heated battle, Duo freed Chaos from the Devil Core and destroyed it, and the pair were then caught up in the effects of the Super Genesis Wave. (MM: #27, SU: 53, StH: #251)
Shattered World Crisis
- From a readers perspective, this picks up from where the original pre-Super Genesis Wave continuity left off
After the planet was broken up due to the Super Genesis Wave, Angel Island was rocked by the rising landmasses. In the midst of this commotion, Chaos emerged from the Master Emerald and dove down to the planet below. He later appeared in the city of Meropis to aid the beleaguered defenders-among them Sonic the Hedgehog and Rotor Walrus. Chaos battled the Dark Guardian and defeated it by manipulating the water around them. Seeing this, Rotor realized that Chaos was responsible for preventing the oceans from draining away from the planetary fragments. Working together, the trio dispatched the Dark Guardian, while the rest of Dark Gaia's Minions were defeated by Coral, Tikal, and Pearly reciting the Mystic Melody with Aquarius. Chaos' presence and the successful restoration of the city's energy shield renewed King Puff and Queen Angelica's faith in Coral's abilities, and she was reinstated as priestess of the Eusebes Shrine. (SU: #63, StH: #263)
As a being composed of pure water, Chaos had the ability to elongate his body to attack enemies from a distance, as well as to change shape in order to dodge attacks or fit in narrow spaces. By absorbing Chaos Emeralds, he has the ability to evolve into progressively stronger incarnations of himself, each differentiated from his original form of Chaos 0 by a number from one to seven, the seventh also being known as Perfect Chaos. Chaos can also manipulate water to a great degree, using it to attack enemies and even preventing the oceans from draining away during the Shattered World Crisis.
- Although Chaos has 8 forms (including its base form) only six of these forms have been seen. This is because it is possible for Chaos to bypass forms if it swallows more than one emerald at once.