English title: Let the right one in.
I loved this film when I watched it in the cinema on its release. Finally got to watch it again this weekend, only took me ten years (Hell how time flies!) I still find it a great film that holds up very well. This is much more a romance than a horror as such. The growing relationship between the young bullied Oskar and Eli is at the centerpiece of the film making it warm and cozy, all the while not saving on the horror elements. As a kid more or less on the sme age as the main characters at the same time (early '80s,) it hits the nostalgia nerve quite well too. I highly recommend this one, even for people who don't traditionally like horror films.
There's also an american remake of this, of course. If you were unlucky enough to have seen that one instead of the original, you have been deprived of a great film!