Shadow the Hedgehog is Sonic's arch-rival. They look almost identical (to the extent that many initially got them confused), and they can match each other in speed, agility, and abilities, including Chaos Control. The two of them first met each other as enemies, with Sonic holding a grudge at Shadow for getting him into trouble with GUN, but they put aside their differences to team up and save the world from Gerald Robotnik's doomsday plans. Since then, they have been both lethal adversaries and comrades.