Name: Mephisto Saturno
First Appearance: Wonder Woman #10 (1944)
Creators: William Marston and H.G Peter
Abilities: Leader of Saturns spy operations on Earth, Psychic powers to prevent others from noticing him. Advanced Saturn technology with properties such as anti gravity, invisibility, behavior control.
Backstory: Head of the Saturns spy operations on Earth. Mephisto Saturno spent years on the planet. Operating in various guises in multiple countries. Studying the planets strengths and weaknesses for the most efficient way for his homeworld the space empire of Saturn to conquer.
For Saturn was a vast and powerful space empire. Having enslaved its own moons, they plotted to expand, claiming whole planets to place under their thumb. Using it for resources and enslaving whole populations to be resold, for on Saturn the only things that mattered was profit and oneself.
Mephisto would be Saturns primary threat to the Earth. Trying again and again. Losing his status as a count on Saturn for his failure, becoming a prisoner, winning back his freedom, and earning the title of Duke to try again and again.
Along the way what was originally a villain motivated by milking the Earth for profit in the name of self interest turned into one bent on revenge and desired the destruction of the Earth itself.