The omen !
Of course I mean the original version from 76 and not the shitty remake from 2006.
I love the old horrors more anyway,recent horror films have no suspense and mostly are a mix of tons of fake blood and lame sound shock effects.
I first saw this as a kid and found it really creepy (the scene at the old cemetery ! or the death of the priest ....)
I just loved the freak accidents XD