Leviathan (/lɨˈvaɪ.əθən/; Hebrew: לִוְיָתָן, Livyatan Liwyāṯān ; "twisted, coiled") is a sea monster referred to in the Bible.
The word has become synonymous with any large sea monster or creature. In literature (e.g., Herman Melville's Moby-Dick) it refers to great whales, and in Modern Hebrew, it means simply "whale." It is described extensively in Job 41 and mentioned in Isaiah 27:1.
Read more about Leviathan: Hebrew Bible, Ancient Middle Eastern Origins, In Later Jewish Literature, Christianity, Leviathan in Satanism