E-102 Gamma

E-102 Gamma was created by Dr. Eggman as the second unit in the E-100 Series. E-102 Gamma was powered by a captured pink Flicky held inside the robot. Although E-102 Gamma was created by and made to work under the orders of Dr. Eggman without question, which involved assisting in empowering the mystical water elemental Chaos, he eventually turned against his maker's will, and devoted his short existence to freeing the animals contained in the other E-100 units.

(Source: Sonic Wiki Zone)