DOCTOR WHO (1968)
I know it’s not a movie but easily the most terrifying thing on screen I can recall was the 1968 Saturday evening Web of Fear episode of Doctor Who, which featured the Yeti killer robots.
I was eight and these huge hairy horrors attacking London seemed so believable.
I was crying behind the sofa and refused to come out until this petrifying programme was over.
Nightmares? Yes! For weeks!