Shadow the Hedgehog (シャドウ・ザ・ヘッジホッグShadō za Hejjihoggu?) is the rival of Sonic the Hedgehog. He was created as the "Ultimate Lifeform" by Professor Gerald Robotnik using the DNA and blood of Black Doom. Shadow is immortal, and does not age. Since his debut, Shadow has appeared in a multitude of games, television shows, and comic books. His past was almost a complete mystery until the game Shadow The Hedgehog revealed the events surrounding his creation. In contrast to Sonic, Shadow is an antihero, or a renegade who can just as easily serve the forces of evil as those of good. According to an official poll, Shadow is the second most popular character in the series, second only to Sonic himself.