Knuckles the Echidna

Knuckles the Echidna is one of the main protagonists in the Sonic the Hedgehog series and one of the protagonists in Sonic the Hedgehog Transformers Prime. He's best friends with Sonic and Tails.

Bio
He is a stoic and pure hearted warrior who has dedicated his life to guard the Master Emerald. He is the only survivor the Echidna clan, and has promised to guard and protect the Master Emerald with his life. He is the prodigy of Sonic's team, and a trusted friend. However, he is a loner by nature.