E-105 Zeta (Ｅ－１０５ "ゼータ",E - 105 "Zēta"?), or E105ζ, is a character that appears in the Sonic the Hedgehog series. It was an animal-powered robot created by Dr. Eggman, and the fifth unit in the Doctor's E-100 Series. Zeta, along with his "brothers", were created during the Chaos incident to serve as the first Egg Carrier's elite crew. After failing his first mission, Zeta got turned into a stationary defense unit in the engine room of the Egg Carrier. Soon after, he was destroyed by E-102 Gamma.
E-105 Zeta started out as a humanoid robot colored in mainly purple and white. He possessed no neck, his head and torso coming together in an almost ellipsoid shape. His torso was purple with a wide and white vertical stribe down the middle, and possessed a head light with a hexagonal gray frame on the right side. He also had gray mufflers surrounding the pelvis area, and had the number "105" painted in white on the right of his large vertical stripe and the left side of his rear. His head meanwhile was small and platform-like with a yellow shade and green cylindrical eyes.
Zeta's shoulders were black vertical cylinders. Attached to each of them were Zeta's arms, which were long and designed with two joints; his left arm held Zeta's black-gray blaster while his right arm had a tri-digited hand with two points of articulation on each digit. Also, Zeta's right upper arm was purple with yellow-orange cuffs, while the parts between his upper arms and forearms were gray. Zeta also possessed two long and inverted legs with five points of articulation and large, black feet with two sharp toes and roller wheels on the heels. The upper sections of his legs in particular were purple while the rest of them were gray, except from his calves, which were thick and purple with gray and yellow-orange cuffs.
After getting remodeled, Zeta appeared very different from other units in the E-100 Series. Although Zeta retained his head and upper torso, these elements would rest on top of what mostly resembled a large stationary tower with a color scheme matching Zeta's. His tower form was round on the sides, with his upper torso section being raised above a wide plaform-like section with a black bottom. He also had seven rocket turrets around his perimeter and had green lights in various places. Most of Zeta rested upon a gray high-tech pillar. He also had several pipes attached to the platform below his upper torso, all of which were bent downward.
E-105 Zeta was created by Dr. Eggman as the fifth unit in the doctor's E-100 Series of robots, with an animal serving as his power source. His purpose was to serve as an elite member of the first Egg Carrier's crew. Together with his brothers Gamma, Delta and Epsilon, Zeta was sent to look for Froggy, who was vital to Eggman's plans. When Zeta returned, however, it was revealed that he had brought the wrong frog. As punishment, Eggman had Zeta discarded from his crew. Soon after, Zeta was rebuilt into a stationary defense unit in the engine room of the Egg Carrier, unable to move, but boasting far more armaments.
Not long after, Gamma, who had defected from Eggman and set out to "save" its fellow E-100 brethren, found Zeta in Hot Shelter, and the two robots engaged in battle. In the end, Zeta was destroyed, and the Peacock powering him was released.
To defeat E-105 Zeta, to the player must destroy the large turrets surrounding the robot. They should run around the arena and flash Gamma's targeting Laser Gun toward the robot when possible. When Zeta launches a volley of missiles from his turrets, the player must keep moving to lure them off course, or target and destroy them. Each time Gamma blows off a turret, E-105's life gauge drops. After landing a total of seven hits, Zeta will be defeated.
Zeta is one of two E-series robots in Sonic Adventure to receive a physical upgrade and change in appearance (the other being Beta). The remaining E-Series robots, including Gamma, only received enhanced Arm Cannons.