Sonic the Hedgehog , trademarked Sonic The Hedgehog, is a video game character and the hero of the video game series released by Sega, as well as numerous spin-off comics, cartoons and books. The first game in the franchise was released on June 23, 1991 in order to provide Sega with a mascot to rival Nintendo's flagship character Mario (see 1991 in video gaming). Since then, Sonic has become one of the world's best-known video game characters, with his series having sold over 45 million copies. In 2005, Sonic was one of the first game character inductees into the Walk of Game, alongside Mario and Link. He has an evil robotic counterpart named Metal Sonic.

Artist Naoto Ōshima, designer Hirokazu Yasuhara and programmer Yuji Naka are generally credited with the creation of the character, a blue anthropomorphic hedgehog, whose ability to run faster than the speed of sound is a major part of the gameplay of the series.