3. Ils (2006)
Ils, or Them, is, similar to many films on this list, a true nightmare because it plays on fears we can all commonly recognise as a person (or people) terrify a young couple in their house late at night. It was part of the French horror revolution which included Haute Tension and Martyrs but the precision in this film makes it a true great. Like many of the best films here, there is one simple idea. Clementine and her boyfriend Lucas, settle down to sleep in their newly acquired country pile. In the middle of the night, they are awoken by music and their car driving off. From there on, it is clear that there is someone in the house prepared to scare them and, potentially, kill them. It is then a nightmarish chase in the manner of the last twenty minutes of Texas Chainsaw Massacre, but this last for seventy minutes. The ultimate pay-off for this film also plays into the fears we hold in this modern society, and the chance it is based on fact highlights this further. It has similar themes to Eden Lake but this is a darker piece that really examines our night-terrors as we awake in a place we feel safe only to discover...someone is out there.