Leviathan is a gigantic imaginary animal believed to live in the sea. In the Bible, it is used to symbolize powerful worldly forces like Assyria or Egypt.
Isa 27:1In that day the Lord with his hard and great and strong sword will punish Leviathan the fleeing serpent, Leviathan the twisting serpent, and he will slay the dragon that is in the sea.
Job 3:8Let those curse it who curse the day, who are skilled to rouse up Leviathan.
Job 41:1Can you draw out Leviathan with a fishhook or press down his tongue with a cord?
Job 41:10No one is so fierce that he dares to stir him up. Who then is he who can stand before me?
Ps 104:26There go the ships, and Leviathan, which you formed to play in it.
Ps 74:14You broke the heads of Leviathan; you gave him as food to the creatures of the wilderness.