fall guy 
noun informal, chiefly North American
A scapegoat: he contends that he is innocent, that he was set up as a fall guy...
- And then they picked this one auditor who could be their fall guy.
- She's obviously being set up to be the fall guy and she's it.
- Whether or not the person who actually takes the blame is the real culprit or a fall guy, we may never know.