Professor Gerald Robotnik (プロフェッサー・ジェラルド・ロボトニック, Purofessā Jerarudo Robotonikku?) is a character that appears in the anime series Sonic X. He was a human scientist and the grandfather of Dr. Eggman and Maria Robotnik.[2][3] Acknowledged as the greatest scientific mind in history,[1] Gerald was a world-renowned scientist responsible for several groundbreaking creations, including his greatest achievement, Shadow the Hedgehog.

Over fifty years ago, Gerald led Project Shadow, a medical program for researching immortality. As a part of the program, Gerald created Shadow the Hedgehog. He was later taken into custody by the military when his work was deemed too dangerous. When learning that Maria was killed by the military, Gerald slipped into madness and spent his last days plotting revenge against humanity.