Bushwhacker

Bush·whack·er

Bushwhacker

n.
  1. One accustomed to beat about, or travel through, bushes. [U.S.]
    They were gallant bushwhackers, and hunters of raccoons by moonlight.
  2. A guerrilla; a marauding assassin; one who pretends to be a peaceful citizen, but secretly harasses a hostile force or its sympathizers. [U.S.]