Although Charlie Luciano comes close because he founded the Commission, I go with Frank Costello. His contribution was to make the Mafia a political powerhouse. Previously, the Irish dominated urban political machines and rented their services, often grudgingly, to Mafia families. Costello stepped in and, through money and sophistication, turned the tables. He was smart enough to maintain Irish ward heelers and officeholders because he knew the public at that time distrusted Italian names in politics. But they were subordinate to him. He made judges and district leaders whenever he needed to, and even elected two mayors of NYC. That's how he earned his nickname, "The Prime Minister of the Underworld."