E-103 Delta was the third of the E-100 Series droids created by Dr. Eggman in 3236. Tasked with locating Froggy that had absorbed Chaos' tail, E-103 brought back a random frog, as had two of the other robots. He along with E-101 Beta and E-104 Epsilon were transported away for their failure. After this, E-102 Gamma, who turned against Dr. Eggman, tracked down and destroyed E-103 Delta along with the other three E-100 series robots.
- Delta's name was never specified in the comics, though his number was present on his arm.