A lumbering mechanical version of Sonic created by Dr. Eggman. Bulkier and less advanced than Metal Sonic, Mecha seems to be pure robot and doesn't possess a sense of self-awareness. He's appeared in several different forms over the years - his attack patterns remain largely unchanged, but it's unclear whether or not his various incarnations are indeed the same machine.

Sonic the Hedgehog 2 (8-bit) Mecha Sonic's earliest form. His spin attack is weak, and can be deflected with a counter spin. Other than that, he simply dashes across the screen and occasionally pauses to eject a short probing hand from his metallic belly. Pitiable.

Sonic the Hedgehog 2 This version is a force to be reckoned with, arguably the most dangerous of the bunch. His jagged spin is deadly and can fling razor shrapnel. His movements are jerky, making his attack patterns difficult to predict. (He appears in this same form in Sonic Pocket Adventure.)

Sonic & Knuckles This version looks nasty, but since his attacks are slower than in Sonic 2, they're easier to predict. He can now absorb energy from the Master Emerald for a temporary burst of power. In his glowing "super" form, he gains extra speed, the ability to fly, and can fire laser blasts.

Sonic Adventure This mysterious black robot may or may not be related to the previous forms of Mecha Sonic. He can only be found floating in a green tube in the hub of Final Egg, across the way from Metal Sonic. Neither one breaks out of their stasis in the course of the game.