Metal Sonic is a recurring main antagonist from the Sonic series. He is the ultimate creation of Dr. Eggman in an attempt to surpass Sonic in every way. He has often fought him but has been beaten every time resulting in Metal Sonic getting stronger somewhat each time due to his adaptive abilities. Soon enough, he has even betrayed his creator during the events of Sonic Heroes, locking him away in order to build up his own robot empire all to get the better of Sonic by gathering the most powerful data to get stronger by assuming the disguise of Eggman during their encounters.

His appearance resembles his base form aside from now having five longer head quills with white stripes, black shoulder pads with a matching belt and long flowing back skirt. His arms and legs are altered to resemble long sleeves and pointed boots respectively.

His abilities compared to before are enhanced greatly due to now possessing a mix of powerful data; the deity Chaos, the ultimate lifeform Shadow and more all while still possessing his natural powers of slight shape-shifting, high speed movement, conjuring shields and energy blasts. Due to his level of transformation be can assimilate with other machinery to assume a large dragon-like form which he calls Metal Madness/Overlord.