A mysterious black hedgehog matching all of Sonic's skills and abilities.
Shadow the Hedgehog is an artificially-created hedgehog created by Gerald Robotnik using alien DNA. He has many if not all of the same abilities as Sonic the Hedgehog, including the ability to harness the power of the Chaos Emeralds, but was created long before Sonic was born.
Shadow's outer appearance is quite unique; while he shares identical proportions with Sonic, he has black fur with red highlights and a white tuft on his torso. The spines on his head bend and point upright rather than down.
He prefers to work alone and distances himself from others, with few exceptions. Though soft-spoken and reserved, he never bluffs; if he makes a threat, he has every intention of carrying it out. This is seen in the Shadow the Hedgehog video game, when Shadow warns Sonic in one of the storylines that if he were to try to stop him, Shadow would inevitably destroy his blue counterpart. Shadow views Sonic as his rival and equal in all aspects of his life, but still sees him as annoying and foolish as he can be. Like Knuckles used to be with Sonic, Shadow has a rivalry with Sonic due to their animosity with each other in terms of how they view their own methods of justice and morality, but will work together despite certain problems they have with one another, and readily come to the others' aid. Shadow is known to treat others in a very callous manner, and in combat, he displays a "killer instinct" that Sonic lacks.