Sonic the Hedgehog protagonist Sonic the Hedgehog, a blue hedgehog able to run at supersonic speeds, and recurring villain Dr. Eggman, an evil scientist whose ambition is to conquer the world. Among Sonic's many allies, the most well-known include: Miles "Tails" Prower, a twin-tailed, highly intelligent yellow fox who is Sonic's sidekick and best friend; Amy Rose, a pink hedgehog who is Sonic's self-proclaimed girlfriend and a hero in her own right; Knuckles the Echidna, a coolheaded red echidna who is the guardian of the Master Emerald; Shadow the Hedgehog, an anti-heroic doppelgänger of Sonic with a dark past; and Metal Sonic, a
Sonic the Hedgehog (character) for Shadow the Hedgehog. "Sonic Heroes" (2003) featured Sonic teaming up with Tails and Knuckles, along with other character teams like Team Rose and Chaotix, against the newly rebuilt Metal Sonic, who had betrayed his master with intentions of world domination. "Sonic the Hedgehog" (2006) features Sonic in the city of water, "Soleanna," where he must rescue Princess Elise from Dr. Eggman while trying to avoid a new threat to his own life, Silver the Hedgehog. He is the only playable character in "Sonic Unleashed" (2008), in which he unwillingly gains a new personality, "Sonic the Werehog," the result of