Call of Cthulhu, duh.
Oh, maybe I should say a bit more than that =) Okay, so I came across the works of H.P. Lovecraft in the mid-80s. I can't remember what got me started but I quickly bought and read every paperback of his works I could get at the bookstore. They're sitting right over there on my bookshelf now. When I bought the first book I was a bit skeptical. I really didn't see how a book could be scary or creepy. But the stories were fantastic and the tidbits of mythos which kept emerging up were delicious. I bought the game soon after and have enjoyed many creepy sessions. One of the things I particularly like about it is the emphasis on investigation and gathering knowledge, all while working yourself closer and closer to your likely demise. It's not a Hollywood-style gun-fest and you won't have a "tank" in the party. It's just not that sort of game. There's also the aspect that you're never quite sure what you're dealing with this time--until it's too late!