The alien invasion scenario is a common one in cinema – and for good reason. If movies are a mirror, reflecting social anxieties and regrets, then the alien invasion trope is one of the most adaptable allegories imaginable. For decades, filmmakers have used it to discuss military policies, fear of technology and concern over environmental abuses. Our scientific progress as a species, in conflict with the moral progress of our conscience, and our natural fear of change, are all to be found in the alien invasion movie. There are three main types of cinematic alien invasion – each serving a different purpose – although variations and combinations do occasionally appear. These are Occupation, Infiltration and Raid.