The Trio of Evil
There are three evil beings that work together in the days leading up to the return of Christ. They are referred to in scripture as the dragon (the devil or Satan), the beast, and the false prophet. Of these three, only one is a human, the false prophet. The other two are evil angels.
And I saw coming out of the mouth of the dragon and out of the mouth of the beast and out of the mouth of the false prophet, three unclean spirits like frogs. Revelation 16:13
And the devil who deceived them was thrown into the lake of fire and brimstone, where the beast and the false prophet are also; and they will be tormented day and night forever and ever. Revelation 20:10
The interplay between these three is such that the lines of distinction between them tend to become blurred. Revelation 13 describes how the dragon gives his power, throne, and great authority to the beast, how the false prophet speaks like a dragon, and how the false prophet performs signs and wonders in the presence of the beast. Because of this integration, worship of one is considered worship of all. It is an unholy trinity of sorts.
This trio of evil works together for the purpose of pulling off the biggest ruse in human history. Their goal is to prevent the return of Jesus because His return is their demise. In order to accomplish this goal, they will try to derail prophecy by making it impossible to fulfill.