Title: Leviathan
Content:   Leviathan (לִוְיָתָן, Līvəyāṯān) is a sea serpent noted in theology and mythology. It is referenced in several books of the Hebrew Bible, including Psalms, the Book of Job, the Book of Isaiah, and the Book of Amos; it is also mentioned in the Book of Enoch. The Leviathan is often an embodiment of chaos and threatening to eat the damned after life. In the end, it is annihilated. Christian theologians identified Leviathan with the demon of the deadly sin envy. According to the Ophite diagram, the Leviathan encapsulates the space of the material world. The Leviathan of the Book of Job is a reflection 
Title: List of animals in the Bible
Content:  lying in wait by a well or a village is repeatedly alluded to. ; Leviathan — The word Leviathan (Hebrew, líweyãthãn), which occurs six times in the Hebrew Bible, seems to have puzzled not a little all ancient translators. The D.V. has kept this name, Job, iii, 8; xl, 20; Is., xxvii, 1; it is rendered by dragon Ps. lxxiii (Hebr., lxxiv), 14, and ciii (Hebr., civ), 26; The word leviathan means a sea-monster in Isaiah 27:1); Job 41 ; Lion — Now extinct in Israel and in the surrounding countries, the lion was common there during the Old Testament times; hence the great number of words in the Hebrew language to signify it; under 
Title: Leviathan
Content:  Leviathan can also be used as an image of the devil, endangering both God's creatures—by attempting to eat them—and God's creation—by threatening it with upheaval in the waters of Chaos. A "Dragon" (Drakon), being the usual translation for the Leviathan in the Septuaginta, appears in the Book of Revelation. Although the Old Testament nowhere identifies the Leviathan with the devil, the seven-headed dragon in the Book of Revelation, is. By this the battle between God and the primordial chaos monsters, shifts to a battle between God and the devil. Only once, in the Book of Job, the Leviathan is translated as Sea-Monster (ketos). In the 
Title: Leviathan
Content:  Anton LaVey in The Satanic Bible (1969) has Leviathan representing the element of Water and the direction of west, listing it as one of the Four Crown Princes of Hell. This association was inspired by the demonic hierarchy from The Book of the Sacred Magic of Abra-Melin the Mage. The Church of Satan uses the Hebrew letters at each of the points of the Sigil of Baphomet to represent Leviathan. Starting from the lowest point of the pentagram, and reading counter-clockwise, the word reads "לויתן": (Nun, Tav, Yod, Vav, Lamed) Hebrew for "Leviathan".
Title: Leviathan
Content:  the older Canaanite Lotan, a primeval monster defeated by the god Baal Hadad. Parallels to the role of Mesopotamian Tiamat defeated by Marduk have long been drawn in comparative mythology, as have been wider comparisons to dragon and world serpent narratives such as Indra slaying Vrtra or Thor slaying Jörmungandr. Leviathan also figures in the Hebrew Bible as a metaphor for a powerful enemy, notably Babylon (Isaiah 27:1). Some 19th century scholars pragmatically interpreted it as referring to large aquatic creatures, such as the crocodile. The word later came to be used as a term for great whale, and for sea monsters in general.
Title: Leviathan in popular culture
Content:  The Leviathan of the Book of Job is a reflection of the older Canaanite Lotan, a primeval monster defeated by the god Baal Hadad. Parallels to the role of Mesopotamian Tiamat defeated by Marduk have long been drawn in comparative mythology, as have been wider comparisons to dragon and world serpent narratives such as Indra slaying Vrtra or Thor slaying Jörmungandr, but Leviathan already figures in the Hebrew Bible as a metaphor for a powerful enemy, notably Babylon (Isaiah 27:1), and some 19th century scholars have pragmatically interpreted it as referring to large aquatic creatures, such as the crocodile. The word later came to be used as a term for "great whale", as well as for sea monsters in general.
Title: Chaos gods
Content: Leviathan (Is referred to as a reptilian aquatic animal in the Bible, but has also been used as an image of Satan). 
Title: Leviathan
Content:  The Leviathan specifically is mentioned six times in the Tanakh, in, , , and twice in. is dedicated to describing him in detail: "Behold, the hope of him is in vain; shall not one be cast down even at the sight of him?" Included in God's lengthy description of his indomitable creation is Leviathan's fire-breathing ability, his impenetrable scales, and his overall indomitability in .In, God is praised for having made all things, including Leviathan, and in , he is called the "tortuous serpent" who will be killed at the end of time. The mention of the Tannins in the Genesis creation narrative 
Title: Leviathan
Content:  Binsfeld likewise classified Leviathan as the demon of envy, as one of the seven Princes of Hell corresponding to the seven deadly sins. Leviathan became associated with, and may originally have been referred to by, the visual motif of the Hellmouth, a monstrous animal into whose mouth the damned disappear at the Last Judgement, found in Anglo-Saxon art from about 800, and later all over Europe. The Revised Standard Version of the Bible suggests in a footnote to Job 41:1 that Leviathan may be a name for the crocodile, and in a footnote to Job 40:15, that Behemoth may be a name for the hippopotamus.
Title: Leviathan
Content:   The word Leviathan has come to refer to any sea monster, and from the early 17th century has also been used to refer to overwhelmingly powerful people or things (comparable to Behemoth or Juggernaut), influentially so by Hobbes' book (1651). As a term for sea monster, it has also been used of great whales in particular, e.g. in Herman Melville's Moby-Dick - Although in the first Hebrew translation of the novel, translator Elyahu Burtinker chose to translate "Whale" to "Tanin" (intending to refer to another sea monster although in Modern Hebrew usage Tanin more commonly translates to "crocodile"), and leave the word "Leviathan" as it is, nodding to the ambiguity of the word "לויתן" in modern Hebrew – in which the word now simply means "whale".

Question: where is the word leviathan mentioned in the bible?
Answer: Book of Job.
Psalms.
Isaiah.