A mythological sea monster who was said to have been defeated by the god Baal. The myth surfaces in the OT where Yahweh has replaced Baal (Ps. 74: 13–14); and the destruction of Leviathan symbolized for Isaiah (27: 1) the final death of the unredeemed—who did not include Israel (Isa. 26: 2 f.; 27: 12–13).