Revelation 17:10

And when he comes, he must remain for a short time. Because the Lord looks upon both the proud and the weak, he mercifully says that the days which are particularly evil are shortened. Surely to both terrify the proud with the adversity of time, …

And they are seven kings - Anciently there were royal palaces on all the seven Roman bills. These were the Palatine, Capitoline, Coelian, Exquiline, Viminal, Quirinal, Aventine hills. But the prophecy respects the seven hills at the time of the beast, when the Palatine was deserted and the Vatican in use.

And there are seven kings,....

He has, both by nature and by office, supreme dominion and power over all things; all the powers of earth and hell are subject to his check and control. From the character of his followers: They are called, and chosen, and faithful. They are called out by commission to this warfare; they are chosen and fitted for it, and they will be faithful in it.

The emphasis palpably is on "a short space," which therefore comes first in the Greek, not on "he must continue," as if his continuance for some [considerable] time were implied, as ALFORD wrongly thinks. The time of external Christianization (while the beast's wound continues) has lasted for centuries, ever since Constantine.

And there are seven kings - Και βασιλεις ἑπτα εισιν· They are also seven kings. Before, it was said, they are seven mountains; here, they are also seven kings, which is a demonstration that kingdoms are not here meant by mountains: and this is a farther argument that the seven electorates are represented by seven mountains, for though the sovereigns of these states ranked with kings, they were not kings: that is to say, they were not absolute and sole lords of the territories they possessed, independently of the emperor, for their states formed a part of the Germanic body.

And there are seven kings - That is, seven in all, as they are enumerated in this verse and the next. An eighth is mentioned in Rev 17:11, but it is, at the same time, said that this one so pertains to the seven, or is so properly in one sense of the number seven, though, in another sense, to be regarded as an eighth, that it may be properly reckoned as the seventh. The word “kings” - βασιλεῖς basileis - may be understood, so far as the meaning of the word is concerned: (a) Literally, as denoting a king, or one who exercises royal authority; (b) In a more general sense, as denoting one of distinguished honor - a viceroy, prince, leader, chief, Mat 2:1, Mat 2:3,Mat 2:9; Luk 1:5; Act 12:1; (c) In a still larger sense, as denoting a dynasty, a form of government, a mode of administration, as what, in fact, “rules.” See the notes on Dan 7:24, where the word “king” undoubtedly denotes a “dynasty,” or “form of rule.” The notion of ruling, or of authority, is undoubtedly in the word, for the verb βασιλεύω basileuō means “to rule,” but the word may be applied to anything in which sovereignty resides. Thus it is applied to a king’s son, to a military commander, to the gods, to a Greek archon, etc. See Passow. It would be contrary to the whole spirit of this passage, and to what is demanded by the proper meaning of the word, to insist that the word should denote literally kings, and that it could not be applied to emperors, or to dictators, or to dynasties. Five are fallen - Have passed away as if fallen; that is, they have disappeared. The language would be applicable to rulers who have died, or who had been dethroned; or to dynasties or forms of government that had ceased to be. […]