I'm tired, so let's keep this simple.
With regards to the current Secret Six series, who do you think is Mockingbird?
It was Lex Luthor in the original Villains United mini-series, but somehow I can't see Luthor financing the turning of an island into a prison for all the world's criminals. It just seems too petty, not nearly super-science enough.
It seems like it's someone with designs on being a ruler, and someone not at all troubled by enslaving people. I thought about Kobra, but I think they'd prefer the criminals be running loose, to help spread chaos and fear. I suppose General Eiling could be behind it. He's a power-hungry scumbag.
I tend to favor Vandal Savage. Smyth kept bringing up how there are all these great achievements through history that relied on slave labor, and Vandal was alive for all of them, so he'd certainly see it as a proven formula. It might also explain why they'd bring in one of his kids to serve as waste disposal, or whatever that monstrosity was supposed to be.
You have any guesses?