Revelation 17:11 - Matthew Poole's English Annotations on the Holy Bible

And the beast that was, and is not, even he is the eighth; this made the eighth succession of governments in the Roman empire. And is of the seven; this was of the seventh head; for although this was the eighth government in order as we have counted them, yet one of these, viz. the seventh, (which was that of true Christian emperors), must not be counted as one of the seven heads, which were all idolatrous: so though this was the eighth government, yet he was one of the seven heads, i.e. idolatrous governments. And goeth into perdition; and to be destroyed as they were.