I like aliens because there you cant kill them off sure you can kill a queen or even a Hive of them but some always escape and repopulate in the Alien Movies 2 through 4 was only one Hive and keep comeing back
Lifecycle, How their like a serpent :) and they work together real good, very sneaky and scary looking. and Doesnt rely on anything but what it was born with. And Demanding to do stuff. and the inner jaw
I like almost everything about them, excluding (not including) Gorrila-Drones, Tiger-Drones, Teredactyle-Drones, and all of that other cheap stuff to make more money off its franchise...