Does anyone know who the most powerful criminal in history is/was?

In before George W Bush.

Wasn't it Lupin the master thief?

Hitler? What makes a criminal? Pretty much every American President since WWII is a nefarious, world policing, natural resource thief embedded with bankers and lawyers that help them make up protective laws as they find new ways to scam weaker less suspecting nations. As long as they keep their people (Americans) somewhat happy enough not to question them, they are unable to be held accountable by any world court system.

After some googling, I think it may be Semion Mogilevich.

Blackbeard Teach. A freebooter on the Spanish Main and a voracious pirate, he was worth a great deal of money taken from Spanish galleons. He became the Governor of Jamaica before he was hung at Tyburn for piracy.