Leviathan
: a twisting aquatic monster, possibly the crocodile of the Nile, and used symbolically of Assyria and Babylonia (by the twisting Euphrates River IBD).
Revelation 12:9
Satan
: a person, male (evil angelic),an angel that has rebelled against God
Revelation 20:1-2
Satan
: a person, male (evil angelic),an angel that has rebelled against God