'Unclean Spirits' in the Bible

And when the unclean spirits saw him, they fell down before him, and cried saying, "Thou art the son of God."

And anon Jesus gave them leave; And the unclean spirits went out and entered into the swine. And the herd startled, and ran headlong into the sea. They were about two thousand swine, and they were drowned in the sea.

And he called the twelve, and began to send them, two and two, and gave them power over unclean spirits.