The Time Lord who invented the Stars and Time Travel
Omega was a Time Lord from the Planet of Gallifrey and another name for him is Peylix. Omega along with President Rassilon had created in the Dark Times for the Time Lords to Travel in Time and Space. He also had created a Living Metal called Valdium. He was inside a Black Hole with his Gel Creatures and he brought people their like The Doctor, Jo Grant and the Brigadier even the Whole Unit Base too. Omega then saw the 2nd and 3rd Doctors in his Chamber and told them he would leave and they would Take his Place. But it was too late for Omega as there was nothing left of him. He had no Head under his Mask and he didn't have a Body at all. As Omega was transported before the Star Blew up the Black Hole into a Antimatter World.
Years Later Omega Returned to Earth with his Ergon Creature helping him to Duplicate the Doctor and take Control of Time and Space. The Doctor Destroyed Omega's Equipment and he was in Amsterdam. Omega then duplicated himself but Shortly Afterwards he turned Green and was Turning Back into Antimater. Omega was dying and then he was Turned into Antimatter and then the Doctor Shot Him with the Ergon's Conversion Gun, as Omega Lost Control of Time.
Omega has appeared in the 3rd Doctor Season 10: The Three Doctors.
Also the 5th Doctor Season 20: The Arc of Infinity.