The one you are thinking of is the Beast from the Pit that comes on the scene when he is released from the pit. That is where he was put during Noah's flood. In counting the kings when Revelation was written Rome was the 6th king. Fast forward to when prophecy (that Revelation covers)starts to unfold and that Beast is given 42 months to be active. The 7th king is Satan, he is the king that has the key that opens the pit and lets out another fallen angel. That angel is the 8th king, the one that was (before the flood), is not (in the pit), and will be (last 1260 days before Christ's return)

The most powerful people during those years will be 10 men and they will have 2/3 of the population going along with teachings that are in conflict of the 2 NT Laws.