Late 14c., “sea monster, sea serpent,” sometimes regarded as a form of Satan, from Late Latin leviathan, from Hebrew livyathan “dragon, serpent, huge sea animal,” of unknown origin, perhaps from root l-w-h- “to wind, turn, twist,” on the notion of a serpent’s coils. If so, related to Hebrew liwyah “wreath,” Arabic lawa “to bend, twist.” Of powerful persons or things from c. 1600. Hobbes’s use is from 1651.
From Etymology Dictionary

‘evidence?’ Leviathan project – black and white photo on satin inkjet paper Oct. 2013
An aquatic animal mentioned in the Old Testament. It is described in Job xli. apparently as a crocodile; in Isa. xxvii 1 it is called a piercing and a crooked serpent; and it is mentioned indefinitely in Ps. lxxiv. 14 as food and Ps. civ. 26. [Century Dictionary]

‘Beast of Water’ (Leviathan?) Black and white photo on satin inkjet paper
*LEVIATHAN is MORTAL