Synonyms of snake in the grass

nounA hidden enemy.

• backstabberA traitor or hypocrite, such as a co-worker or friend assumed trustworthy but who figuratively attacks when one's back...
• wolf in sheep's clothingSomeone who or something which is harmful or threatening but disguised as something peaceful or pleasant.
• betrayerSomeone who betrays, or reveals confidential information; a squealer or informer.
• double-crosserOne who double-crosses; a traitor.
• quislingA traitor who collaborates with the enemy.
• ratA person who is known for betrayal.
• ratter
• recreantSomebody who is recreant, who yields in combat; a coward or traitor.
• renegadeA disloyal person who betrays or deserts a cause, religion, political party, friend, etc.
• serpentA person who is subtle, malicious, treacherous, or deceiving.
• snakeA person who acts deceitfully for personal or social gain; a treacherous person.
• traitorOne who betrays any confidence or trust.
• treasonistOne who commits treason.
• cockatrice archaicAn evil, deceitful, or destructive person.
• swike dialectal, obsoleteA deceiver; betrayer, traitor.
• treacher archaicA traitor or deceiver.
• treacherer archaicA treacher, a traitor.
• turntippet obsoleteA traitor; a defector; a renegade.
• withersake archaicAn apostate or perfidious renegade.