'Monster' in the Bible

In that day Jehovah, with his sore and great and strong sword, will visit leviathan the fleeing serpent, and leviathan the crooked serpent; and he will slay the monster that is in the sea.

Awake, awake, put on strength, O arm of Jehovah; awake, as in the days of old, as in the generations of passed ages. Is it not thou that hath hewn Rahab in pieces, and pierced the monster?