An unwanted guest can ruin a dinner party, a vacation, a marriage, or in the case of these movies, an entire nervous system. From home invasion thrillers to psychological dramas where politeness becomes a survival mistake, these films understand the horror of watching someone walk through the door and slowly take control of the room. Whether it is mother! turning hospitality into apocalypse or Sexy Beast proving one man can poison a sunny villa just by arriving, the best movies about unwanted guests make one thing painfully clear: sometimes the real nightmare starts after you let them in.
