Theme: Parasites

In biology, a parasite is a lifeform that lives on, in or by attaching itself to a host and feeding from them. Genre cinema has adapted the idea to its own uses and gives us a variety of lifeforms that attach themselves to humans (almost always) and control or feed upon them.

The most famous parasite in genre cinema would be the chestburster in Alien (1979). Body Snatchers films are filled with a good many other parasitic alien lifeforms that take over and control humans or even the dead as part of an Alien Invasion. The horror genre has developed a number of variations of their own.