Grandfather of Dr. Julian Ivo Robotnik in the Sonic the Hedgehog universe from Sega.

Every villainous mastermind has some evil growing in his family tree, and Dr. Robotnik is no exception. Nearly 50 years ago, Professor Gerald Robotnik was one of the greatest scientific minds to grace the Earth. His research led to the creation of the world's first space colony, the ARK. Aboard the ARK the professor, his granddaughter Maria, and teams of researchers performed research to create "the ultimate life-form", a being that was supposed to unite mankind in peace and brotherhood. At some point, however, something went wrong and the government arrested and inprisoned the professor for conducting dangerous experiments. They raided the ARK, killed everyone aboard in the ensuing retaliation, and shut down the station.

With the death of his granddaughter, Gerald went insane. He felt that he had lost everything. He blamed mankind for his troubles and planned his elaborate revenge. His evil plan: if the cannon aboard the ARK were to be activated at full power (with all seven Chaos Emeralds powering it), it would fall out of orbit and impact the Earth, wiping out every living thing on the planet. He was also able to complete work on Shadow the Hedgehog, a living clone of Sonic the Hedgehog who could finish the professor's demented plan. Before he was executed, Gerald left behind his diary telling that to release Shadow would be to fill the world with hate and dispair; the same pain that he had to live with after losing Maria. Gerald's team had also been working on the secret Biolizard project, but information on that was lost as time went on. His other project, Emerl the fighting robot, was also corrupted for evil over time.

The professor was seen in video clips and flashbacks in Sonic Adventure 2 for the Sega Dreamcast and Sonic Adventure 2 Battle for the Nintendo GameCube. His grandson obviously follows in his footsteps to destroy the world.

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