E-102 Gamma

The Sonic the Hedgehog video game franchise began in 1991 with the game Sonic the Hedgehog for the Sega Genesis, which pitted a blue anthropomorphic hedgehog named Sonic against a rotund male human villain named Doctor Eggman (or Doctor Ivo Robotnik). The sequel, Sonic 2, gave Sonic a fox friend named Tails. Shortly afterward, Sonic CD introduced Amy Rose, a female hedgehog with a persistent crush on Sonic, and Sonic 3 introduced Knuckles the Echidna, Sonic's rival and, later, friend. All five of these have remained major characters and appeared in dozens of games.

The series has introduced dozens of additional recurring characters over the years. These have ranged from anthropomorphic animal characters like Shadow the Hedgehog and Cream the Rabbit to robots created by Eggman like Metal Sonic and E-123 Omega, as well as human characters like Eggman's grandfather Gerald Robotnik. The series also features two fictional species: Chao, which have usually functioned as digital pets and minor gameplay and plot elements, and Wisps, which have been used as power-ups.

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Wikipedia