Seelkadoom

Seelkadoom is a black Hedgehog, with blue stripes all over his spikes, representing the stripes that Shadow has, and Sonic's fur color. He has his skin shown on his arms and belly, representing Sonic's body with it's color being tan, representing Shadow's skin color. He has a pair of sneakers that look like Sonic's, only they are colored dark gray instead. Seelkadoom has the personality combined of Sonic and Shadow, only evil and more destructive. He also appears to have his own personality, likely because of his negative Chaos Energy side.

Like Sonic, he never misses an opportunity to mock and tease his opponents, even in a fight, representing Sonic's arrogance and irreverence but remaining threatening, showing in Episode 8 how Seelkadoom tells Sonic that "looks that light speed just isn't enough". He also appears to be very arrogant, insensitive and aggressive, very similar to Shadow, only much more violent, showing how he doesn't care much about his partner, Reala, and that he only uses him as a pawn, scolding him when he messed everything up, regarding their plans to take the Sapphire, as well as feeling no remorse for Reala's death in Episode 7, claiming that "his death was well deserved". It is also represented, where Seelkadoom claims himself as "the superior hedgehog", and therefore mostly toys with his counterparts in battle more than their other friends, NiGHTS and Knuckles, whom he knocks them out with a simple attack, showing disinterest in fighting them. Furthermore, after his birth, Eggman called him "Sonaw", which angered Seelkadoom, to which he changed it to his desired name, showing a strong sense of liberty just like Sonic, although he doesn't care when it happens to the other.