Douglas Birely, born in Culver, California, was once a geneticist employed by a private research company in his home state. He specialized in the effect radioactivity had on mutation. Birely went to his employers seeking clearance to experiment with live subjects, his hypothesis being that the target would acquire super powers by means of mutation, but was denied. He proceeded to move forward with his experiment anyway, choosing to illegally experiment on himself, which later resulted in him being fired. Birely's hypothesis, however, proved to be untrue as he contracted a lethal skin cancer. To stop the effects of the cancer, Birely created devices that he wore under a synthetic stretch fabric. With his new life-sustaining costume came his newly adopted identity as supervillain, Doctor Demonicus.
Demonicus learned of a highly radioactive meteorite that had entered Earth's atmosphere and landed in the Aleutian Islands. He came into possession of the meteorite and dubbed it the Lifestone. The Lifestone had the ability to create monsters by mutating living organisms and with it Demonicus created Ghilaron, Centipor, Lepirax, and Batragon, being also mutated himself by the meteorite.
Major Story Arcs
Establishing a base on one of the Aleutian Islands and organizing a group of criminal troops, Doctor Demonicus began to raid oil tankers, using both his troops and his mutated monsters. His operations were halted when his monsters were defeated by Godzilla. Demonicus himself was overcome by Gabe Jones of S.H.I.E.L.D. and taken into custody.
After acquiring freedom once again, Doctor Demonicus allied himself with an alien, the Myndai, Maur-Kon, who provided him with his space station base. Demonicus assisted Maur-Kon against the Shogun Warriors with his genetically and robotically engineered monsters, Cerberus, Starchild, and the Hand of Five. The Shogun Warriors were victorious over his creations and stopped his attempt to launch a meteor strike at Earth from his base. Demonicus was again taken into S.H.I.E.L.D. custody.
Doctor Demonicus returned to supervillainy again when he managed to capture Godzilla, mutating him and controlling him. He had Godzilla attack the West Coast Avengers. Demonicus then salvaged Iron Man's original armor and used it to continue his assault but was foiled by the founding Avenger himself.
Under Doctor Demonicus's rule, the Pacific Overlords were formed. They were defeated however in battle by the West Coast Avengers and Sunfire.
From the floor of the Pacific Ocean, Doctor Demonicus raised a land mass north of Hawaii. He declared himself as the the ruler of his island-nation, Demonica. Demonicus was rejected in an attempt to have his nation recognized by the United Nations. Demonica sank to the Pacific floor once again with Demonicus escaping in the process.
Doctor Demonicus was among the 43 villains to escape the Raft. during the massive breakout courtesy of Electro. He was recruited into the Hood's organized group of supervillains and was later defeated by Doctor Strange in a battle with the New Avengers.
During the final battle with the Skrulls at Central Park in New York City during the Secret Invasion, Doctor Demonicus fought under the Hood alongside the Avengers.