Knuckles the Echidna (Sonic Underground)

Knuckles the Echidna is the super-strong guardian of the Floating Island and protector of the Chaos Emerald that keeps it afloat. He would defend it with his life against all who trespass on it. He first appeared on the show when he captured Sleet and Dingo because he was tricked into believing that the Hedgehog Triplets were going to steal the Chaos Emerald. Sonic changed his mind, and now Knuckles is on their side. He also has a crush on Sonia.

Sonic Underground is the first TV show Knuckles appeared in, the next being Sonic X.