Fallen angels are angels who fall from God’s grace and are punished by banishment from heaven, becoming Demons.
The three versions of the book of Enoch associate fallen angels with the Watchers, 200 angels who descend from heaven to cohabitate with women and corrupt humanity and are severely punished by God. 2 Enoch speaks of four grades of fallen angels:
1. Satanail, the prince of the fallen one. Satanail was once a high angel who thought he could be greater than God and thus was cast out of heaven on the second day of creation. He is imprisoned in the fifth heaven.
2. The Watchers, who also are imprisoned in the fifth heaven, dejected and silent.
3. The apostate angels, the followers of Satanail who plotted with him and turned away from God’s commandments. They are imprisoned in the second heaven, a place of “darkness greater than earthly darkness.” There they hang under guard, waiting for the “measureless judgment.” The fallen angels are dark in appearance, and they weep unceasingly. They ask Enoch to pray for them.
4. Angels—possibly some of the Watchers—who are sentenced to be imprisoned “under the earth.”
In Christianity, Lucifer is the arrogant, prideful angel cast out of heaven, mentioned briefly in Isaiah as “Son of the Morning” or “Morning Star.” One-third of the heavenly host fell with him—133,306,668 angels, according to lore. They fell for nine days. Theologians have posited that a portion of each of the nine orders of angels fell; some said the fallen ones compose a tenth order. The fallen angels become Demons who seek to ruin men’s souls, a view reinforced by the influential theologian St. Thomas Aquinas. Lucifer later became identified with Satan.