Chaos (STC)
From Sonic - Wiki on Neoseeker
Chaos was, in a sense, created by Sonic. Sonic was pulled back in time to the time of the ancient Echidna tribes. There, he aided them in their fight against a warlike race of creatures. These creatures, being physically weak, wore powered humanoid suits of armour for mobility and strength. Sonic attacked one of these suits, removing the head (which contained the pilot). A Chaos Energy leak was triggered, and its comrades left it to die. However, instead of killing it, the Chaos Energy surrounded the creature, transforming it into Chaos.
Chaos was at some point captured and fell into the hands of Dr. Robotnik. Ivo experimented with ways to control Chaos, and developed a device supposedly able to achieve control. However, he realised it did not work, and abandoned the project. Grimer, looking for a way to cheer up his boss, released Chaos intending to control it. He did not, however, read Robotnik's journal. He realised his mistake when Robotnik explained that the device was worthless.
Chaos attacked the Metropolis Zone, and in a battle with the Freedom Fighters killed Johnny Lightfoot. This battle briefly weakened Chaos, but left Sonic depressed and angry. He briefly left the Freedom Fighters, but soon returned to fight Chaos. Chaos eventually acquired the seven Chaos Emeralds and became Perfect Chaos. The climactic showdown with Perfect Chaos saw the return of Super Sonic. He absorbed Chaos' power, returning him to his previous form. Super Sonic discarded Chaos into a pool, where it was presumably eaten.
