The "evil" counterpart of Sonic the Hedgehog in Sonic Adventure 2 and its Nintendo GameCube port Sonic Adventure 2 Battle. Created by Professor Gerald Robotnik (the grandfather of Dr. Julian Ivo Robotnik), Shadow was locked away with the elder Robotnik's research after his capture and imprisonment. When the professor's grandson broke into the military's storage locker years later, he freed Shadow from captivity. Shadow then put the professor's final plan of revenge into motion: the destruction of the planet at the hands of the Space Colony ARK's massive laser. Shadow belives himself to be the ultimate lifeform. He misses the professor's granddaughter, Maria, desperately and has vowed to keep his promise to her (whatever that is...). He sees Sonic the Hedgehog as an inferior fake of himself and has vowed to destroy him. He can equal Sonic's speed with the aid of special sneakers. Shadow can also utilzize the Chaos Control, a powerful maneuver involving using the Chaos Emeralds to warp space and time in order to travel distances in the blink of an eye.

Shadow was missing and presumed dead, but he returned mysteriously in Sonic Heroes, the next chapter in the Sonic saga, with no memory of previous events. Searching for his missing memories, he joins up with Rouge the Bat and Omega-123 to form Team Dark. He also shows up in Sonic Battle as part of the fight against Dr. Robotnik.