Fallen angels are heavenly beings portrayed as losing their place or proper condition through transgression. Enochic descent, Satan’s refusal to honor Adam, and the war in Revelation are distinct accounts that later interpretation can bring together.
Leviathan appears in biblical poetry and later religious symbolism. The vivid descriptions belong to different literary contexts and should be interpreted accordingly.
The serpent in Genesis 3 persuades the woman to eat from the tree of knowledge. The chapter does not name Satan. Later texts and interpretations connect the serpent with the Devil, adding to the history of the Eden story.