The 'Fallen Angel' is a Jewish and Christian concept based on the 300BC Book of Enoch. Tanniyn, the dragon-monster, occurs throughout the Old Testament, and Christians have adopted this idea of the Dragon and his angels who do battle against the Archangel Michael:

“And his tail swept away a third of the stars of heaven, and threw them to the Earth".

“ . . . the great Dragon was cast out, that old serpent . . . which deceiveth the whole world; he was cast out (down) onto the Earth, and his angels were cast out with him”.

(from the Book of Revelation/Apocalypse)