In the serial of Sonic the hedgehog, Ivo Robotnik is Sonic 's worst enemy. He was drawn by Naoto Ohshima. He may be one of the very first mean character becoming so famous in the video game story.

DR Robotnik is the elder son of the professor Gerald Robotnik, he is a genius with an IQ of 300 and has a very childish behaviour. His ultimate goal is to conquest the world by turning everybody into robots to get them under control. He is an obese man, with an egg-shaped body. Sometimes he is drawn with long arms, and sometimes with very short ones. He is black-eyed with red wards, but his glasses give him a scientist aspect.

He builds a lot of robots, including some of them who look like Sonic or himself. In most of the video games, the mean character is the final boss to defeat in order to finish the game.
But in Sonic 's games, DR Robotnik is the boss of every level ending. In the major part of the versions, DR Robotnik 's machine is different from a level to another.

In Japan, Dr Robotnik is called Dr Eggman. He tries to find out emeralds of chaos so as to use their strength. This scenario is partially integrated to recent versions of the game, and mostly in the TV show.