Doctor Eggman

Dr. Ivo "Eggman" Robotnik is a mad genius bent on world domination and the main antagonist of the Sonic the Hedgehog video game series.

Although a universally evil (if slightly goofy) scientist and warlord in the cartoon series and early games, The Doctor has slowly become more of a "grey morality" character who will ally with his sworn enemy Sonic the Hedgehog when he feels the need to do so. Though he is a fairly treacherous "ally" and views Sonic as a worthy opponent, but also a thorn in his side who must be eliminated, when the hedgehog messes with the doctor's plans. Dr. Eggman also has a short temper whenever his plans are foiled.

Early Games
Originally known exclusively as Dr. Ivo Robotnik in the localizations outside Japan, Dr. Eggman did not have much of a story going for him.