Revelation 16:14
For they are spirits of demons, which perform [supernatural] signs. These spirits go out to the kings of the whole world to assemble them for battle on the great day of Almighty God.
Revelation 19:19-21
Then I saw the beast [See 13:1ff], and the kings of the earth and their armies assembled together to wage war against the One who was riding on the horse [i.e., Christ. See verse 11] and His army.
Revelation 20:8-9
and he will [again] go out to deceive the nations which are [located] throughout the whole world --- Gog and Magog. [Note: Based on Eze. 35-40, it appears that these names are used here figuratively for all the forces of wickedness which are enemies of God]. Satan will assemble them together for battle, and they will be as numberless as the sand on the seashore.