The Others (2001)

Alejandro Amenábar's haunting thriller stars Nicole Kidmanan as Grace Stewart, who lives in a mansion on Jersey in the days just after WWII with her two children. Also part of the household are three elderly servants who appeared as if from nowhere to replace those who left suddenly. The two children, Nicholas and Anne are photosensitive and must never be exposed to light, so all curtains and doors are kept firmly shut. Anne starts claiming that there are other people in the house, something Grace denies until inexplicable events begin to convince her that they are not alone. But who are these Others?