(demon Behemoth from Collin de Plancy's Dictionnaire Infernal, 1863)

This demon is based on the description of an animal in the biblical Book of Job. It is fairly certain that either the elephant or the hippopotamus is being described, but not clear which:

"Behold now behemoth, which I made with thee; he eateth grass as an ox. Lo now, his strength is in his loins, and his force is in the navel of his belly. He moveth his tail like a cedar: the sinews of his stones are wrapped together. His bones are as strong pieces of brass; his bones are like bars of iron. He is the chief of the ways of God: he that made him can make his sword to approach unto him. Surely the mountains bring him forth food, where all the beasts of the field play. He lieth under the shady trees, in the covert of the reed, and fens. The shady trees cover him with their shadow; the willows of the brook compass him about. Behold, he drinketh up a river, and hasteth not; he trusteth that he can draw up Jordan into his mouth. He taketh it with his eyes; his nose pierceth through snares." (Job 40:15-24)

The writer probably never actually saw the beast he described, whether it is an elephant or a hippo. The references to a tail like a cedar and a nose that pierces through snares suggest the elephant, but the connection of the beast with a river suggest the hippopotamus. The traditional guess was an elephant, as you can see from the illustration above, but modern scholars are leaning more toward the hippopotamus.

Behemoth became demonized early on in his history. In the Book of Enoch he is a monster who dwells in the desert wastes. "But the male is named Behemoth, who occupied with his breast a waste wilderness named Duidain, on the east of the garden where the elect and righteous dwell..." Wild and barren places were the usual habitation of demons, because no human beings lived there to disprove the tale.

From the line in Job that reads "his strength is in his loins, and his force is in the navel of his belly" Behemoth became a demon of lust and gluttony, and more generally of the excesses of physical indulgence. This, despite the use of this animal by the biblical author to illustrate God's wonderous power to create life.