Doctor Sun is a character that appears in the Sonic the Comic series published by Fleetway Editions. He is apparently a kindly man who set up a sanctuary in the Mystic Cave Zone where Mobians could escape from the rule of Dr. Robotnik.
He gathered around him a cult called the Followers of Doctor Sun, who played video games and read comic books all day. Any who wished to join his order were permitted to pass through the Salvation Doorway into the inner sanctum.
In fact, Doctor Sun was Robotnik, and used the cult to turn Emerald Hill Folk into Badniks - the inner sanctum contained a machine for just this purpose. Robotnik considered this his smoothest operation ever, since people were actually volunteering to be Badniks (although they did not realise that until it was too late). However, Sonic discovered the plot when he came in search of one of Doctor Sun's followers, a badger named Stripes. Sonic removed Robotnik's disguise and destroyed the Badnik-making machine, ending Doctor Sun's cult for good.