folk devil

(idiomatic, sociology) A person or type of person blamed by the public for various ills, as during a moral panic.

Example: 1987 July 9, Steve Lohr, "Newcastle Journal: Half of England where jobs are as rare as Tories," New York Times (retrieved 27 Feb 2009):
  It may be true, as Fred Robinson, a senior researcher at Newcastle University said, "Many people view Mrs. Thatcher as a kind of folk devil."
1996 Dec. 18, Robert Verkaik, "‘Crash’ tackling," The Independent (UK) (retrieved 8 June 2014):
  "Every time things become problematic we start careering towards social causes and pick on a folk devil to attribute all evil."
2013 Oct. 20, Jesse Walker, "Conspiracies: Five things they don’t want you to know," Boston Globe (retrieved 8 June 2014):
  There is always a tendency, in the mainstream as much as the fringes, to blame real or imagined social problems on a folk devil.