When families put down roots in strange and unfamiliar places, danger often lurks in the shadows.
NOTABLE CONTENDERS: Hondo, Two Rode Together, countless B-movie Westerns
James Cameron smartly updates this trope: the settlers in peril are colonists terra-forming a distant planet and the cavalry called into save them are some rowdy space marines. Only this time, the bad guys are parasitic xenomorphs with acid.
(VIDEO: 10 Questions for James Cameron)