The Euphrates river dries up, and spirits of devils go to the kings of the earth to gather them for the Battle of Armageddon. Jesus declares that He is coming like a thief.
And the sixth angel poured out his vial upon the great river Euphrates; and the water thereof was dried up, that the way of the kings of the east might be prepared. And I saw three unclean spirits like frogs [come] out of the mouth of the dragon, and out of the mouth of the beast, and out of the mouth of the false prophet. For they are the spirits of devils, working miracles, [which] go forth unto the kings of the earth and of the whole world, to gather them to the battle of that great day of God Almighty. Behold, I come as a thief. Blessed [is] he that watcheth, and keepeth his garments, lest he walk naked, and they see his shame. And he gathered them together into a place called in the Hebrew tongue Armageddon. (Revelation 16:12-16)
The “kings of the earth” would at least include the ten kings that give their power to the beast for one hour to make war with the Lamb.
And the ten horns which thou sawest are ten kings, which have received no kingdom as yet; but receive power as kings one hour with the beast. These have one mind, and shall give their power and strength unto the beast. These shall make war with the Lamb, and the Lamb shall overcome them: for he is Lord of lords, and King of kings: and they that are with him [are] called, and chosen, and faithful. (Revelation 17:12-14)
Other passages that speak of God gathering the nations for judgment:
I will also gather all nations, and will bring them down into the valley of Jehoshaphat, and will plead with them there for my people and [for] my heritage Israel, whom they have scattered among the nations, and parted my land. And they have cast lots for my people; and have given a boy for an harlot, and sold a girl for wine, that they might drink. Yea, and what have ye to do with me, O Tyre, and Zidon, and all the coasts of Palestine? will ye render me a recompence? and if ye recompense me, swiftly [and] speedily will I return your recompence upon your own head; Because ye have taken my silver and my gold, and have carried into your temples my goodly pleasant things: The children also of Judah and the children of Jerusalem have ye sold unto the Grecians, that ye might remove them far from their border. Behold, I will raise them out of the place whither ye have sold them, and will return your recompence upon your own head: And I will sell your sons and your daughters into the hand of the children of Judah, and they shall sell them to the Sabeans, to a people far off: for the LORD hath spoken [it]. Proclaim ye this among the Gentiles; Prepare war, wake up the mighty men, let all the men of war draw near; let them come up: Beat your plowshares into swords, and your pruninghooks into spears: let the weak say, I [am] strong. Assemble yourselves, and come, all ye heathen, and gather yourselves together round about: thither cause thy mighty ones to come down, O LORD. Let the heathen be wakened, and come up to the valley of Jehoshaphat: for there will I sit to judge all the heathen round about. (Joel 3:2-12)
A noise shall come [even] to the ends of the earth; for the LORD hath a controversy with the nations, he will plead with all flesh; he will give them [that are] wicked to the sword, saith the LORD. (Jeremiah 25:31)