'Unclean Spirits' in the Bible

And they were all amazed, so that they questioned each other, saying, What is this? New teaching with authority; even the unclean spirits doth he command, and they obey him!

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

And he gave them leave. And the unclean spirits coming out, entered into the swine; and the herd rushed down the steep into the lake, about two thousand, and were drowned in the lake.

And he calleth to him the twelve, and began to send them forth by two and two; and gave them power over the unclean spirits;