This one is a little weird. The Twilight Zone show was not just horror but also science fiction, drama and comedy all rolled together. Whether or not you got a pure horror episode was a crap shoot but it was the first popular TV show to dwell on this fringe of storytelling. The Outer Limits would follow soon along with a coterie of imitators. Rod Serling was mostly interested in telling morality plays with lots of genre window dressing.
I just read an article on the scariest TZ episodes but I won't rehash it here. It seems I am woefully behind on my scary TZ eps. The only one I have seen on the list was the one where the mannequins come to life in the after hours at a mall. I remember, as a kid, seeing one of the relaunch episodes that focused on a search for a missing scientist. The search party finds rats the size of horses scattered dead all over the lab. I know they keep finding larger and larger animals until the last shot is their elevator ascending into the gaping maw of a giant spider. Woof, no thank you.
What are your favorite Twilight Zone episodes?