In Thomas Hobbes's book, with the same title published in 1651, Leviathan is defined as a symbolic term for the political commonwealth's absolute power. Their acknowledged leaders must be subject to and accordingly are under divine control.
This reaches back to primeval myths about a sea monster in the Ugaritic texts where Baal overcomes Lothan (ltn, a linguistic variant of Leviathan) recounted as a seven headed serpent, likely identified with Prince Sea who was Baal's adversary. The Bible also depicts Leviathan as a part of the sea 1 with many heads 2 and is the event preceding creation. 3 Apocalyptic literature tells that battle will be returned to in the end time when the evil Leviathan is ultimately defeated.
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9 and later traditions relate that Behemoth as food to the elect
10 is another retelling of creation in Psalm 74:14. In Job 41, entirely under God's control, Leviathan is observed as a divine pet. 11
Biblical experts in the Oxford Companion to the Bible note that many have ascribed Job's Leviathan to a crocodile but dismiss the suggestions as unlikely. While acknowledging that some similar characteristics exist between the two however, they go on to reason, that fire breathing abilities do not, in comparison to other biblical references along with the Canaanite antecedents, determine it to be a creature of mythological origins.
Sources:
The Holy Bible
Michael D. Coogan, The Oxford Companion to the Bible , 1993.