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 (1991 video game) and toys. "Sonic the Hedgehog" is one of the best-selling video game franchises of all time, with over 150 million copies sold by May 2014. The game's first stage, Green Hill Zone, has been used in several games, such as "Sonic Adventure 2", "Sonic Generations", "Sonic Mania", "Sonic Forces", and the "Super Smash Bros." series. The game's popularity inspired a number of unofficial variants, including "Somari", a pirated Nintendo Entertainment System conversion of the game featuring Nintendo's Mario character in levels from the original "Sonic" game, "Sonic the Hedgehog Megamix", a total conversion mod of the original game, and "Sonic