Friday the 13th. This deserves a special rant. I'll admit it - I enjoyed watching these slasher films. Not because I'm psychotic or sick, but they were fairly entertaining. It started off with an unseen slasher, a surprise ending, and then another surprise ending. Part 2 introduced the infamous Jason, though he covered his head with a potato sack with eye-holes cut out. Part 3 was in 3-D, which didn't help, but he gained the hockey mask (which I'm not sure was better than the potato sack, but it did cement that famous image.) Part 4 was his first "real" death, and could have, some would say should have, ended the series. Part 5 featured an imitator, though we didn't find out until the end, followed by a twist ending. Part 6 resurrected Jason and he truly became unstoppable (as well as rotting.) Part 7 had the telekinetic girl, its only real claim to fame. Part 8 was the cruise-ship-to-New York one, high on humor and low on sense. Part 9 took off in a mystical (and often stupid) direction and had the ending that sets up the upcoming Freddy-vs-Jason movie. Part 10 was set in the future, featuring spaceships and such, and was offbeat but highly entertaining.
My old roommate actually rented these on laserdisc, one by one, and we had a marathon that spanned a couple of weeks. You can see our highly unusual reviews indexed (under the "F" section) here.