......my Dad collected every word Ray Bradbury ever wrote, so I'm pre-disposed to be spooked by carnivals.
But in my opinion, the all-time, hands down, everybody-else-get-in-line best series in this genre is "Twilight Zone". Scripts that literate and intelligent have all but disappeared from television and films today...and I hold out no hope of them every returning.
Another one that was uneven but sometimes really quite good was the Sixth Sense, starring Gary Collins as a parapsychologist. Both the series and the star seem to have vanished into a black hole. It aired in the late Sixties and early Seventies.
Boris Karloff's Thriller. It lasted, I believe, only one season and was one of the creepiest, most atmospheric anthologies ever aired. It would alternate with one episode dealing with suspense, the other with the supernatural. The Sci-Fi Channel use to broadcast the show (reruns, of course) but has not done so for years.