Dr. Ivo "Eggman" Robotnik

Dr. Ivo "Eggman" Robotnik is the main antagonist of Sonic the Hedgehog series. He is Sonic's arch-enemy.

Sonic the Hedgehog
Sonic is Dr. Eggman's arch-enemy.

Miles "Tails" Prower
Dr. Eggman and Tails are both enemies and rivals.

Metal Sonic
Metal Sonic is Sonic's robotic copy created by Eggman.

Knuckles the Echidna
Knuckles is constantly tricked by Eggman, due to Knuckles' naivety.

Dr. Eggman Nega
Eggman Nega is Dr. Eggman's descendant.

Shadow the Hedgehog
Dr. Eggman and Shadow are either allies or enemies, depending on Shadow's goal.

Orbot
Orbot is one of Eggman's henchmen.

Cubot
Cubot is one of Eggman's henchmen.

Gerald Robotnik
Gerald is Dr. Eggman's grandfather.