There's nothing that says the seven kings are Roman Emperors. The word translated "hills" makes that leap. I think the 6th head the one "who is" is most probably an Emperor of Rome. Please note it's the 8th King who rises from the abyss and goes to destruction, again quoting Daniel of the AntiChrist.
Tim, there are three fundamental considerations which I will mention - that if you grab hold of these will make a big difference in your eschatology growth.
1. The prophecies are all built around the 7 year period of Daniel 9:27.
2. The person (I don't know his name) will be on a track to become the King of Israel (illegitimate) - the Antichrist.
3. The person will be on another track to become the King of Rome - the little horn, the 7th king. Then later, after a 3 plus year stint as the Antichrist, he becomes the 8th King of Rome - the beast.
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King of Rome
King of Israel
Those two concepts are critical to recognize and see the person in two different capacities - at different times on our end times timeline.
Note that the person as the King of Israel, sandwiched between being the King of Rome. This is critical to understand.
King of Rome - the 7th Julio-Claudian king - the little horn (right before the 7 years begin)
King of Israel - for a 3 plus year stint - the Antichrist. (begins the 7 years)
King of Rome - the 8th Julio-Claudian king - the beast. (basically the second half of the 7 years)
In most of Revelation, it focuses on the person as the King of Rome. The only place in Revelation, the person is seen as the Antichrist, King of Israel, is as the rider on the white horse in Revelation 6, who is given the crown, becoming the King of Israel (illegitimate) at the beginning of the 7 years.
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The Juiio-Claudian kings were a family - the Caesar family. They were tied together as a family.
They were...
1. Julius Caesar
2. Augustus Caesar
3. Tiberius
4. Caligula
5. Claudius
6. Nero
end times - the 7 years.
7. The little horn * (right before the 7 years begin)
8. The beast (* same person extended 42 months)
Revelation 17:10
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.