Eggman Nega also known as Doctor Eggman Nega is the third most recurring villain in the Sonic game series and has been the main villain and final boss of all three games he’s been in: Sonic Rush, Sonic Rivals, and Sonic Rush Adventure. He is the primary nemesis of Blaze the Cat and Silver the Hedgehog. His design appears reminiscent to the older Dr. Eggman from the Genesis Sonic games, albeit with the colors reversed, a longer nose, a white mustache (suggesting he is at an eldery age), pointy blue sunglasses, and visor-styled goggles instead of normal ones.
In the Sonic Rush series, Eggman Nega (spelled NEGA, with all caps) is introduced as an extra-dimensional counterpart of Doctor Eggman from Blaze’s home dimension. He is more cruel and calculating than the Eggman from Sonic’s world, although the two often work together, and he has sent Blaze’s world into ruin, which is why he sets out for the Sol Emeralds. He is eerily polite for such a cold and calculating person. His downside, however, is that he can sometimes lose track of important details while making unnecessary speeches.
While Eggman himself is first thought to be the primary antagonist in Sonic Rivals, the player soon finds out that Eggman Nega has captured Eggman and is disguising himself as him. In Sonic Rivals, Eggman Nega is from 200 years in the future (which reflects the Blaze of Sonic the Hedgehog). Using a special camera, he turns several objects and characters into cards, with the objective of turning the world into a card that he will be able to control. During the somewhat ambiguous ending of the game, Nega is captured inside a card of his own by Silver, yet it was never revealed how he freed himself from the card that he was imprisoned in for the sequel. In Sonic Rivals 2, Eggman Nega tries to power and awaken an inter-dimensional monster called the “Ifrit” to destroy the world by using the Chaos Emeralds and the Chao to do it after reading old files of Professor Gerald Robotnik. However his plans were foiled once again and now he’s stuck in the ifrit’s Dimention.