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) little brother, and is uninterested in marital proposals from Amy Rose. In times of crisis, he focuses intensely on the challenge as if his personality had undergone an astonishing change. Sonic's greatest strength is his running speed, being known in the game's universe as the world's fastest hedgehog. Many of his abilities are variations on the tendency for hedgehogs to roll into tight balls for protection with the addition of spinning his body. Since his introduction in 1991's "Sonic the Hedgehog", Sonic's primary offensive maneuver is the basic "Spin Attack" (or "Sonic Spin Attack"). Later games in the series expanded