Though the beast has seven heads (= kings), the beast itself has its own mind so as to fit exactly in the row of seven and “belong to the seven.” There is no contrast between the kings of the earth (they conspire against the Lord and his anointed, Psalm 2:2) and the beast; they are of one blood (recall Revelation 13:6). Again, we are not to read this as if the angel would tell John that one day there shall arise a literal king who is the beast personified; the figures and numbers of Revelation are symbolic.
11 As for the beast that was and is not, it is an eighth but it belongs to the seven, and it goes to destruction.