A Nightmare on Elm Street
We love the sequels to A Nightmare on Elm Street just as much as the next guy, but the 1980 version has all the rest beat. Wes Craven unleashed Freddy Krueger onto a generation that was, frankly, not prepared to be afraid of going to sleep. All other Freddy Krueger movies are great, don't get us wrong, but this one takes the cake.
The Changeling
This movie came out in 1980. It didn't have an all-star cast, nor did it have a particularly earth-shattering advertising budget. What it did have, was genuine production and a terrifying plot. The Changeling is about a composer who moves into a haunted mansion in Seattle, but in this case, "haunted" means something that you may have never seen before.