Sonic the Hedgehog (ソニック・ザ・ヘッジホッグ, Sonikku za Hejjihoggu?) is a supersonic hedgehog that can mover faster than the speed of sound (765 mph, which is faster than Mach 1), with lightning reflexes to match (hence the name Sonic) and loves adventure. He acknowledges the fact that the Earth is just as cool and blue as he is. He is 15 years old, stands at 100 centimeters (3 ft 3 in), weighs 35 kilograms (77 lbs) and was born on natal Island. Artist Naoto Ōshima, designer Hirokazu Yasuhara and programmer Yuji Naka are generally credited with the creation of the character, a blue-furred, blue and-peach-skinned, green-eyed, anthropomorphic African pygmy hedgehog, who has the ability to mover faster than the speed of sound and possesses the ability curl up into a ball (like a regular hedgehog), primarily to attack enemies. This is a major part of the gameplay of the series.

Sonic seems to have a holy or avatar-like position (despite, on most occasions, being unaware about his involvement in the future of the world he's saving), as many of his adventures in the series coincide with the fulfillment of ancient prophecies, specifically his involvement in Echidna legends (such as: the mural on angel Island that depicts Super Sonic fighting Eggman for the Master Emerald).