'Unclean Spirits' in the Bible

And all were amazed, so that they questioned together among themselves, saying, What is this? what new doctrine is this? for with authority he commands even the unclean spirits, and they obey him.

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

And Jesus immediately allowed them. And the unclean spirits going out entered into the swine, and the herd rushed down the steep slope, into the sea (about two thousand), and were choked in the sea.

And he calls the twelve to him; and he began to send them out two and two, and gave to them power over the unclean spirits;