Doctor Droid is a giant, towering and powerful cyborg lifeform from outer space who created a large army of robots to do his bidding.
Droid himself bears some resemblance to the late Dr. Robotnik.
Droid and his army came to Mobius 20 years after the events of the series, and declared war on the restored Kingdom of Acorn, bombarding the restored Mobotropolis and Droid's troops besieging the Royal Palace. Sonic, now King, remained behind to face the enemy and allow Sally, now Queen, to take their two children Sonia and Manik and retired King Maximillian and escape in a transport pod to a far away location. Sonic most likely escaped and rejoined his family at a later time. Meanwhile, Droid and his army attacked Echidnaopolis on Angel Island, raising most of the city to the ground, in the hopes of securing the Master Emerald. However, a now-battle hardened Knuckles summoned his inherited Chaos abilities and destroyed Droid and his army.
Apparently though, Doctor Droid's character was used in Sonic Super Special #7. In this story, Droid blackmails a mysterious mutant named Particle by kidnapping her sister. With her under his control, Droid forces Particle to steal the Master Emerald by using a machine to go to Sonic's universe at about the same time Sonic had just defeated Doctor Robotnik (STH: #50). After she ran into Sonic, the Freedom Fighters, and Knuckles, she succeeded in stealing the Master Emerald for Droid and brought it back to the Image Universes' New York city. Sonic, Knuckles, and the Freedom Fighters give chase with aid from Image comics heroes Shadowhawk, Savage Dragon, Union, Velocity, and the Maxx. Droid introduces himself to Sonic and Knuckles and completely baffles them (and the reader) by saying that he knows them both quite well (apparently, this story was written with the intention of keeping his character around). After some fighting, more introductions, and Particle's switch to the heroes' side, Knuckles uses his Chaos powers shown to him by Locke to stop Droid's mad plan to recreate reality his way. This results, surprisingly, in Droid's death even though they had plans to keep him in the Mobius: 20 Years Later story arc.
- Doctor Droid was supposed to be featured in the upcoming "Mobius: 20 Years Later" series in Knuckles the Echidna comics, and the character and hints of the storyline were seen in Knuckles #25 (in Locke's dream) and Sonic Super Special #11 (in Sally's vision with the Source of All), though it was cancelled after the Knuckles series was cancelled as well, in favor of "Mobius: 25 Years Later". Also it would have revealed the possible future storyline in "Sonic: In Your Face" would have been the true future of Sonic, and as such wasn't shown, as the writers of the series have decided not to show the final true future of the characters until the end of the series itself.