The Royal 'Corrupt' Hedgehogs is a group that appears in the Sonic Underground television series. They are a royal family comprised of alternate reality counterparts to Sonic the Hedgehog, Sonia the Hedgehog and Manic the Hedgehog. They exist in an alternate dimension, and together they are the rulers of their version of Mobius. Their absolute power over the planet ended up corrupting them, thus turning the siblings into cruel and arrogant tyrants, who held an impoverished Mobius and its inhabitants in an iron grip. After being defeated by their good counterparts and shown how destructive their reign had been to the lives of their citizens, the Royal 'Corrupt' Hedgehogs realized the errors of their ways and agreed to restore their kingdom to one of peace and prosperity.
After the Oracle sent them to an alternate-dimension Mobius on a training mission, the Sonic Underground came across alternate versions of themselves that were the rulers of Mobius, but had let the power corrupt them. There was no sign of the alternate trio's version of Queen Aleena, suggesting they had either ruled without her supervision and guidance or that they had eliminated her. Each of the three is seen on a video camera performing cruel deeds for ridiculous reasons; the corrupt Sonic was willing to destroy an entire sector of Mobotropolis for the crime of music having been heard there, the corrupt Manic was imposing heavy taxes that forced his subjects to live in poverty and the corrupt Sonia ordered the imprisonment of not just a man who failed to prepare a diamond necklace for her on time, but his entire family as well.
Their universe's good and honorable Robotnik said that the three of them hadn't set foot outside the palace in years. The Sonic Underground was brought to their world by the Oracle on a mission and were mistaken for their tyrannical counterparts by the resistance set up by the Good Robotnik. After being captured, the siblings were able to persuade the Good Robotnik they were not their counterparts by playing him a song, something the corrupt hedgehogs would never do. Good Robotnik released them, and they then concocted a plan to remove their corrupted selves from a position of power, at least temporarily.
The Underground first infiltrated the palace by pretending to be the corrupt royals and fired every SWATbot guard they passed (ordering them to pass on the message and saving a cook, tailor and impoverished tax payer along the way). The three then faced off against their respective counterparts. Manic used a vehicle with a suction device (how he got it is neither shown or mentioned) to first suck up the vast wealth his counterpart had accumulated, then informed his counterpart on who he was (at which point the corrupted Manic shouted for his guards, not knowing they had been fired) and then in an attempt suck up the corrupt Manic, trapped him on the machine's hose nozzle. Sonia pretended to be a reflection of her corrupt self in an empty frame her counterpart had mistaken for a mirror, then scared her by shouting "BOO". After informing her confused counterpart on who she was (her exact words being "I'm you, but WAY better, girlfriend"), corrupt Sonia called for her guards but to no avail. She fainted when the Underground Manic appeared with his alternate self still trapped on the machine's nozzle.
Sonic then confronted his other self, eating the corrupt Sonic's Chili dogs and commenting on how they were "Dee-lish". The corrupt Sonic got angry and called for his guards, but once again they were not there. Underground Sonic then challenged the corrupt Sonic to a race across the enormous dining room table (in which he would go backwards) and almost won until his counterpart used a gun that traps its victim's feet to make him fall over. He revealed he had re-hired the guards and was awaiting their return, but this was turned against him when Robotnik and his Swatbots came through instead. He attempted to escape, but was stopped when Sonic used his own gun against him.
The three corrupt hedgehogs were then made to see up close the dire state of the populace and repented for their selfishness, though the corrupt Manic resisted at first by saying they needed something (probably money), but he was interrupted by his Underground counterpart who told him to "Look with your eyes, not your mouth, bud". They then held a public gathering where the no-longer corrupt Sonic claims they will be good from then on and provide luxuries such as "music and chili dogs for all". On their way home, Queen Aleena (in a vision) informed the Sonic Underground that the point of their mission had been to show Sonic and his siblings precisely what happens when power corrupts.
- When their titles are mentioned, they are referred to as "Prince" and "Princess" rather than "King" and "Queen", despite it being made clear that they rule over their Mobius. It is unknown why this may be.
- Though it is most pronounced in Sonia, the corrupt Sonic and Manic are also quite vain; the Underground first learned of their doppelgangers existence through statues of them in the palace courtyard.
- The origins of the three are still unknown, as are the answers to many mysteries surrounding them; how they obtained the Swatbots and the location of their relatives being a few.