I was around 7-8 when I started playing Diablo. And every time I heard the Butcher say "AH, FRESH MEAT!" I nearly soiled myself, holy hell was that game scary back then.
This was the only game where I had to walk away from the computer a while to get over my fear, I don't know how I made it to Diablo in the first place.
Perhaps it was due to my age, but still that's the scariest game I've ever played.