Did you really think this wouldn't be on the list? It is the essential Halloween movie.
The plot: After spending 15 years in an institution for murdering his sister, Michael Myers return to Haddenfield for a court appearance. He is deeply disturbed and is escourted by Dr. Loomis (played brillantly by Donald Pleasance). He escapes and returns home.
What can I really say that hasn't already been said about this 1978 classic. It made Jamie Lee Curtis an instant scream queen.
I love everything about the original movie. Michael Myers wasn't just a killer, he was almost supernatural in essence. Which is why he's often referred to as "The Shape". The movie basically kicked off the 80's slasher sub-genre and made the "final girl" and stable in horror.
Watch the original, uncut version. You'll get a terrifying experience.