The idiom “a wolf in sheep’s clothing” has Biblical origins. Ancient Greek fables offer warnings similar to those offered in the Bible. Today, the phrase serves as a warning against anyone with a friendly face and malicious intent.
The phrase remains popular. In fact, it has its own Tumblr page.
Apparently, the phrase is a popular inspiration for tattoos as well.
This subject was inspired by #WerewolfWednesday, which I hold each week on my Facebook page.
ADRIANLILLY.COM 
Reblogged this on The Horrifically Horrifying Horror Blog and commented:
Reference material for writers…
Thanks!
Great post, enjoyed it a lot!
I am partial to the flock 😉
I see that. Nice site!