Dr. Robotnik, or Underground Robotnik, is the native version of Dr. Robotnik in the Sonic Underground dimension. He is extremely similar to his Prime Robotnik counterpart in that he battles against his own version of Sonic, captures and roboticizes the Mobians on his world, and is an oppressive and cruel dictator of Mobius. Underground Robotnik has two henchmen in bounty hunters Dingo and Sleet.
Before Giant BorgEdit
Like the Prime Zone, Dr. Robotnik began his rule by seizing the great city of Mobotropolis from the current monarch, in this case Queen Aleena, and has it converted into his capital city: Robotropolis. After a bounty was placed on the newborn children of the queen, she was forced to go into hiding. Meanwhile, Dr. Robotnik roboticized each Mobian citizen but keep the wealthy around to help fund his polluted factories. Queen Aleena was forced to separate with her offspring after hearing a prophesy from the Oracle of Delphius. Dr. Robotnik would have each of the children’s caretakers captured and roboticized. Yet resistance was met in the form of the queen’s children, who were now grown. Sonic, Sonia, and Manic, now part of a musical band would grow to be the biggest thorn in Dr. Robotnik’s rule since he came into power. (SSS: #10)
Giant Borg’s AttackEdit
Evil Sonic would come to invade the Sonic Underground dimension one day, seeking out pieces of the Giant Borg, only to be captured by Dingo and Sleet. When brought in, he would mistake Dr. Robotnik for an alternate version of him called Robo-Robotnik. Likewise, Dr. Robotnik would also mistake Evil Sonic for his version of Sonic, Underground Sonic. Evil Sonic would give him all the pieces of the Giant Borg, but Dr. Robotnik had him sent away anyway to be roboticized. Meanwhile, Robo-Robotnik secretly witnessed this and would abandon his mission in recovering the Giant Borg. (SSS: #10)
Dr. Robotnik would reassemble the Giant Borg and used it to seek out Sonia, Manic, and the rest of their resistance. To his surprise, Underground Sonic would come out to challenge him, even though he thought he captured him. Using a heat-seeking-missile, Dr. Robotnik fired upon Underground Sonic, only to be taken by surprised by two other versions of Sonic: Zonic the Zone Cop and Sonic the Hedgehog Prime. Underground Sonic would then turn the missile back at the Giant Borg, destroying it and ending Underground Robotnik’s rampage. He was last seen hanging from a pole above a building, mocked by the free citizens. (SSS: #10)
In the Sonic Underground TV Series Robotnik has a slightly different appearance. In The TV Series his cape is red, the lower half of his outfit is black, his center circle is red and his right arm is completely covered in armor. While in the comics he looks exactly like Robotnik Prime.