After the creation of Sonic the Hedgehog, Ohshima chose to use his previous egg-shaped character to create the antagonist of the 1991 video game, Sonic the Hedgehog, as well as making him become the archenemy of the series' eponymous main character. Robotnik is a rotund mad scientist who plans to conquer the world in order to build his own Eggman Empire.
While he has gone through several major and minor appearance changes throughout the series, his in-game designs retain several basic characteristics, such as his egg-shaped body, red-black-yellow clothing, pince-nez sunglasses, and large mustache.
It was not until 1999's Sonic Adventure that the character was called both "Eggman" and "Robotnik" in the English version, with all following English releases to date referring to him as "Doctor Eggman".
Yuji Naka has explained that "Robotnik" is the character's true last name while "Eggman" is a nickname taken after his shape.
Most of the Sonic games released before Sonic Adventure featured him as the final boss that the player fights at the end of the game.He attacked West Side Island, turning its animals into robots.He was intercepted by Sonic and his friend Tails who saved the animals and retrieved the Chaos Emeralds before the evil scientist.In April 1990, Sega commissioned its AM8 R&D department to create a character who would replace Alex Kidd as the company's mascot, as well as compete against Nintendo's flagship character, Mario.The idea of an egg-shaped character became the basis of the visual design for Eggman.Additionally while he is normally enemies with Sonic and his friends, Eggman has worked alongside them to combat greater threats such as when he works to stop the Space Colony ARK from crashing into the Earth in Sonic Adventure 2 or against rival villains such as the Marauders in Sonic Chronicles: The Dark Brotherhood though after these threats have been neutralized Eggman returns to being an enemy of Sonic. Eggman in his game appearances, as well as in other media.His first voice actor was Masaharu Satō, who portrayed him in the arcade game Sega Sonic the Hedgehog.While it was announced that the rest of the cast would be replaced from Sonic Colors onward in 2010, Pollock retained his role as Doctor Eggman, now making him the longest serving voice actor to portray the character in English.Pollock reprises the role in the Sonic Boom animated series.Robotnik is able to launch the Death Egg, but it fails to get into orbit before Sonic sends it crashing back down into the Lava Reef Zone.Robotnik later reveals his true plan to Knuckles after stealing the Master Emerald during a fight between Sonic and Knuckles and gets the Death Egg into space once again in Sonic & Knuckles.