'Wolves' in the Bible

"Beware of false prophets who come to you in sheep's clothing, but inside are ravenous wolves.

"Behold, I am sending you out like sheep in the midst of wolves. Therefore be wise as serpents and innocent as doves.

Go! Behold, I am sending you out like lambs in the midst of wolves!

I know that after my departure fierce wolves will come in among you, not sparing the flock.