The Royal 'Corrupt' Hedgehogs are the main antagonists of the Sonic Underground episode "Six is a Crowd"
They are the alternate universe counterparts of Sonic, Sonia, and Manic. Instead of being the prime dimension personalites, Alternate Sonic is a glutton (much like Homer Simpson), Alternate Sonia is spoiled and Alternate Manic is greedy. At the end of the episode, they reform after their prime counterparts show them what they did to their people.
Like all three of their good, prime counterparts, the entire trio are voiced by Jaleel White.