What is shadow the hedgehog?

Answer 1

Shadow the hedgehog is a character from the Sonic the Hedgehog series's. He is an experimental artificial life form in the design of a black, male, anthropomorphic hedgehog that was created around 50 years prior to the events of Sonic_Adventure_2by professor Gerald using the alien Black Doom's blood. He resembles Sonic in many ways, such as how his hover skates propel him at extreme speeds to rival those of Sonic; but he distinguishes himself with greater use of his signature ability to use Chaos Control with the Chaos Emeralds, which allow him to warp time and space. He has been featured in a variety of media, including his own self-titled game. Shadow is an antihero, and easily works together with either Sonic's group or Dr Eggman, depending on what suits his own needs.

Answer 2

Mephiles the Dark if you want to count Sonic 2006. If not, then the Shadow Androids.