I remember being scared stiff watching Doctor Who as a kid. It had really dodgy effects and costumes back then but I didn't know any different at that age. I kept watching it anyway, because it was a very safe way to be scared if you know what I mean.
The Exorcist was an actual movie and not a TV show that created mixed emotions world wide when released. I was a teenager at the time and remember well when it was released. The scariest one I remember was the original Twilight Zone and Outer Limits series. Even the latest ones now don't even come close to these two.
As a kid, I was petrified of the X Files. My sister and I would watch it when our mum went out on a Wednesday night and our dad fell asleep on the couch. We would then think we'd heard something at the door and worry we'd be kidnapped. These days I cringe at the ads for American Horror Story.