I don't think HALLOWEEN is the scariest movie ever made, but it's the film of the day. Saw it when it first came out - and probably saw it the next night, too. Here's what HALLOWEEN did - it wasn't the first stalk and slash film, but it was the first one to get it right... so all of the ones that came after it copied and stole from it without mercy. The cavalcade of bodies scenes comes from this film - even though PSYCHO kind of sets the stage with Mrs. Bates in the fruit cellar. And one of the reasons why we all saw it was because it was Janet Leigh's daughter.
Carpenter really took the time to *build* the suspense and create the dread - and the film sticks with you. He also came up with story details that made it seem real... and frightening. And, unlike the stupid remake, Carpenter knew the way to scare the crap out of you was to show a perfectly normal suburban family and world... and have the killer come from that world. The cute little kid who knocks at your door tonight? Michael Myers. He's sweet and polite and maybe a *member of your family* - and he could just take a knife and stab the life out of you...
If he saw you having sex. It's not about family (stupid sequels), it's not about some pagan cult crap (stupid sequels), Michael sees his sister naked and kills her. Michael sees PJ and Nancy in sexual situations - and kills them. Dude doesn't like sexual situations!
Carpenter's shots are elegant, he makes Michael into a ghost - he's there one minute and gone the next... so you never know when or where he will pop up. This film still works (unlike the remake). The film was made for $300k... and made $58 million.