My ideal Syndicate:
Ultraman was sent to Earth to conquer it ala Goku. Superwoman is an Amazon who was sent to conquer "man's world" in the name of the Amazons. In an uneasy truce, she and Ultraman married to keep the peace. But they both resent each other. I kind of like the Justice Lords concept where they "turned evil" because of some event that happened. That's much better "evil" JL than a group actually calling themselves the "crime syndicate".