Scourge The Hedgehog
Origin of Scourge (from comic series):
On his birthday, Rouge and Scourge tried to steal the Master Emerald, but their plan failed when Locke (Knuckles' father) caught them in the act. Scourge made a final attempt at the Emerald and jumped on top of it. He then absorbed it's power, giving him his Green fur and blue eyes. as for the scar, before Scourge could absorb all of the Emerald's power, Locked slashed Scourge on his chest, leaving two scars that look like the Roman numeral "II"