Job 41
v.1
“Can you pull the leviathan with a fishhook or tie down his tongue with a rope?
Biblically, Leviathan would therefore most easily fit into the category of “supernatural” creature (like cherubim) as opposed to natural or purely mythological. As such it may appear in extrabiblical mythology, as well as being symbolized by something like a crocodile (as in Ezek 29:3, though Leviathan is not specifically referred to in that context).