Mary, mother of Jesus
Ever? Cleopatra! As Queen of Egypt she controled N. Africa and for a while was influential in The Roman Empire! Octavian was so afraid of her he had her assasinated and told the world it was suicide.
Queen Dido of Carthage
I think the most powerful woman on this planet is not known to the great public. I think she has more money than you can imagine and a lot of influence and she doesn't need Twitter, Facebook or fan sites for that.
I don't know who she is, but I know she exists.
Power is the regalia of the rich...