Revelation 17:10; There Are Seven Kings
Revelation 17:10 And there are seven kings: five are fallen, and one is, and the other is not yet come; and when he cometh, he must continue a short space.
The angel further explains that when Antichrist comes, he must remain a little while (cf. Revelation 12:12).
His empire will be short-lived; he will be given “authority to act for forty-two months” (13:5; the second half of the Tribulation). Then the angel offered the enigmatic comment that the beast which was and is not, is himself also an eighth and is one of the seven, and he goes to destruction. How can the beast (Antichrist) be an eighth king and also one of the seven? The answer lies in the phrase the beast … was and is not. Antichrist will be one of the seven kings before his supposed demise and resurrection and an eighth king afterwards during the second phase of his rule. As noted earlier in verse 8, Antichrist will go to destruction—eternal damnation in the lake of fire (Revelation 19:20; 20:10).
Revelation 19:20 And the beast was taken, and with him the false prophet that wrought miracles before him, with which he deceived them that had received the mark of the beast, and them that worshipped his image. These both were cast alive into a lake of fire burning with brimstone.
Revelation 20:10 And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever.
Unlike the first six empires, his empire will be destroyed by a direct act of God.
The angel further explained that the ten horns which John saw are ten kings. They cannot be known to any earlier generation because they have not yet received a kingdom, since they are part of Antichrist’s future empire. They will receive authority as kings with the beast for one hour. Perhaps Antichrist’s empire will be divided into ten administrative regions, which these ten kings will rule under him. The reference to one hour is a figure of speech that emphasizes the brevity of their rule; their reign will be short-lived because their master’s empire itself will be short-lived. During their brief reign, they will be unanimously devoted to Antichrist; they will have one purpose, and will give their power and authority to the beast. They will do his will, and his will alone.
MacArthur, J. F., Jr. (2000). Revelation 12–22 (pp. 170–171). Chicago: Moody Press.