Who is the Beast in John's prophecy?

John’s description of the Beast depicts a figure inspired by Satan, the Dragon who also comes from the Abyss. The Beast mimics Jesus, the Lamb, whose death and resurrection signaled his defeat, seeking to maintain his influence over the earth dwellers. 

The Beast demands worship and loyalty from the inhabitants of the earth, using the kingdoms and rulers of the earth to exercise control. The seven kings and the ten kings that John associates with the seven heads and ten horns of the Beast could have been understood in the first century as depicting specific Roman emperors and their allies, or as depicting the political system and cultural and religious practices of the Roman Empire more generally. John’s interpretive comments suggests that he understands the Beast as the political, cultural, religious, and economic systems that Satan uses in order to thwart God’s purposes—to no avail, as God will destroy the forces of evil when the end comes. 

The connections that John establishes with Old Testament traditions and with his own statements about God the Almighty and about Jesus the Lamb confirm that he wants to assure his readers that Jesus’ victory at the cross and resurrection was decisive. Despite the continuing activity of Satan and his minions, God’s victory at the end will come swiftly, ending the ability of Satan to influence history.

Schnabel, E. J. (2011). 40 Questions about the End Times. (B. L. Merkle, Ed.) (pp. 173–174). Grand Rapids, MI: Kregel Academic & Professional.