'Wolves' in the Bible

Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves.

Behold, I send you forth as sheep in the midst of wolves: be ye therefore wise as serpents, and harmless as doves.

Go your ways: behold, I send you forth as lambs among wolves.

For I know this, that after my departing shall grievous wolves enter in among you, not sparing the flock.