The E-Series ( Ｅ－シリーズ , E - shirīzu ? ) are a robot line that appears in the Sonic the Hedgehog series . They are a production line of robots created by Dr. Eggman , who uses them in his quest to conquer the world. They are considered to be elite versions of the Badnik robots Eggman used in earlier games. The name was first used in Sonic Adventure .
E-101 Beta ( Ｅ－１０１ "ベータ" , E - 101 "Bēta" ? ) , or E-101 “β” , is a character that appears in Sonic Adventure and Sonic Adventure DX: Director's Cut . He was the first animal -powered E-100 Series robot created by Dr. Eggman . Initially intended to serve onboard the Egg Carrier , Beta lost the position to his "younger brother" E-102 Gamma . As such, he was discarded by Eggman and upgraded into E-101 Mark II .