<P> 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 more recently, Wisps, which have been used as power - ups . </P> <P> The Sonic games keep a separate continuity from the Sonic the Hedgehog comics published by Archie Comics and other Sonic media and, as a result, feature a distinct yet overlapping array of characters . </P> <P> Sonic the Hedgehog (ソニック ・ ザ ・ ヘッジ ホッグ, Sonikku Za Hejjihoggu), trademarked Sonic The Hedgehog, is a blue anthropomorphic hedgehog and the main protagonist of the series . Developed as a replacement for their existing Alex Kidd mascot, as well as Sega's response to Mario, his first appearance was in the arcade game, Rad Mobile (as a cameo), before making his official debut in Sonic the Hedgehog (1991). Sonic's greatest ability is his running speed, and he is known as the world's fastest hedgehog . Using the power of the seven Chaos Emeralds, he becomes Super Sonic and can achieve even greater speeds . </P> <P> Doctor Ivo Robotnik (ロボ トニック, Robotonikku), better known by his alias Doctor Eggman (ドクター ・ エッグマン, Dokutā Egguman), is a mad scientist and the main antagonist of the series . Debuting in the first game of the series, Sonic the Hedgehog, he was shown attempting to collect the Chaos Emeralds and turn all of the animals inhabiting the land into robots . He is a self - proclaimed or certifiable genius with an IQ of 300 . His fondness for mechas has made him a renowned authority on robotics . Ultimately, Eggman's goal is to conquer the world and create his ultimate utopia, Eggmanland (alternatively known as the Eggman Empire and Robotnikland). </P>

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