Trigon

Satan is Nicolae Carpathia and Leon Fortunato's spiritual guide, and the true main antagonist in the entire Left Behind series. As the main antagonist, he is God's ultimate enemy, and will do anything to get all people into the Lake of Fire.

Information
Satan was once known as Lucifer, the brightest and most beautiful angel there was; however, because of his pride and selfishness, there was war in Heaven. After learning that they were defeated, Satan and 1/3 of the angels were cast down with him, and was renamed Satan. He seeks rebellion against God, and imbues Leon with powers to call down fire from heaven, to perform miracles in the sight of the world.