Mr Delta is a villain who, along with Ms Alpha, Mr Beta and Mr Gamma, attempted to steal the treasure of the Floating Island. Delta was the brains of the group, using his many gadgets to give them an advantage over Knuckles the Echidna and the Guardian Robots. He was temporarily a member of the Doctor Robotnik Appreciation Tribe, although this was just to get him onto the island. Mr Delta appears to have extremely poor sight, requiring spectacles almost as big as Dorothy.
Upon landing in Megopolis City, Delta and the others quickly departed towards the tunnels, although Knuckles soon caught up with them. While Beta wsa fighting Knuckles, Delta used a laser on Knuckles to blind him, allowing him to be thrown off the island. A group of Guardian Robots, sent by Porker Lewis, soon came to challenge them and Mr Delta found he had trouble subduing them. Eventually, he was able to scan the robots' frequency and urged his teammates to change their chameleon circuits, rendering them invisible to robots. Despite his success, he remain frustrated, taking offence to Gamma's surprise that the technology worked.
Mr Delta had very little more to do after this, simply following his team to the goal. When it appeared that his technology had failed and the Guardian Robots had found them, Mr Delta slipped into a state of shock, repeatedly stating that he "just couldn't understand" the defeat. He was taken to the cage with the rest of the D.R.A.T. members and presumably taken away by the authorities.
Trivia
- Mr Delta shares his name with E-103 Delta, a robot from Sonic Adventure.