wolves in sheep's clothing

Noun

wolf in sheep's clothing (plural wolves in sheep's clothing)

1. (idiomatic) Someone who or something which is harmful or threatening but disguised as something peaceful or pleasant.
   • He ſaith, He doth not plead for all who go under the name of Miniſters in England; he fears there is many of them no better than Wolves in Sheep's Clothing, &c. Then why doth he not come out, and cry againſt them, but remain amongſt them in their Practice? For wherein can he clear himſelf of any...1659, Edward Burroughs [i.e., Edward Burrough], “Some of the Principles of the Quakers (Scornfully so Called by Men) Vindicated, and Proved Sound, and True, According to the Scriptures: …”, in The...

   Synonyms:

   wolf in a lamb's skin, backstabber, betrayer, cockatrice, double-crosser, quisling, rat, ratter, recreant, renegade

   Antonyms:

   paper tiger, sheep in wolf's clothing