Metal Knuckles is a robotic doppelganger of Knuckles the Echidna from the Sonic the Hedgehog series. He is an artificial fighter built to mimic Knuckles’ strength, speed, and combat style, often appearing as an enemy or rival in games and related media. As a mechanical counterpart, he serves as a tough boss-like obstacle and a symbol of Eggman’s technological imitation of Sonic’s allies.