Daughter
The daughter, Sarah, was easily the creepiest part of the movie. Nothing says cliched horror flick like a freaky, young girl. Through most of it, she looks like she's strung out on heroin, with the deep red bags under her eyes.
That and the popping up randomly, sometimes with weird costumes (or was it all in the mom's head?) or 'sleepwalking' in the middle of the field late at night. Or maybe everyone in the family was victim of the darkness in their own way.