In the Roman Empire, Tyrannus claims to be a "sorcerer", but is actually a scientist far ahead of his time. He was exiled by Merlin to Subterranea, a network of caves and tunnels miles beneath the Earth's surface. There Tyrannus discovers a race of orange-skinned semi-humanoid Subterraneans who are eager to find in him a new master to serve. He also discovers a pool of liquid which he drinks to maintain his youth through the centuries. The Subterraneans acquaint Tyrannus with examples and records of technology designed by the Deviants who were their original masters. Tyrannus' scientific genius enables him to master and improve upon the Deviants' scientific wonders over the centuries. Tyrannus becomes Emperor of the Tyrannoid Subterraneans, and an aspiring conqueror.
In the modern era, Tyrannus is finally ready to use this technology and the Subterraneans in conquering the surface world. Tyrannus makes several attempts at conquering the surface world as well as fighting wars against the forces of a new arrival in Subterranea, the Mole Man.
Here's a character who's lived for thousands of years, belonged to shadowy conspiracies (which existed long before The Illuminati and The Cabal) that manipulated events behind the scenes, and controlled an army of little dudes that look like The Greys.
Truly, if there was ever a character with untapped possibilities for some nice conspiracy stories, here he is. Take him out of his quaint Roman uniform, add a touch of The Count of St. Germain, add some UFO conspiracies, and take him as seriously as the X-Men creators (Chris Claremont, Dave Cockrum and John Byrne) took Magneto seriously, and you've got a character who could be as cool as Ra's al Ghul. It's not like it would take much to give him a makeover, just a reassessment of and commitment to what's already there.