I know we just had some Karloff to kick off yesterday--but A) Day 7 of 32 Days of Halloween is generally begun with something from an anthology (such as One Step Beyond or the revived Twilight Zone or the original.
And B) he is Boris Freaking Karloff, after all. This is from the anthology series Thriller, which we've talked about before. (And which is now available in a badass complete series boxed set, I might add.)
This is "The Incredible Doktor Markesan," in which Karloff himself plays a brilliant part. Also in the cast is--you're not hallucinating--Dick York. Even if you don't have time to watch the whole thing, at least watch until Karloff, in his role as the host, shows up. Get at least eight minutes in. Not just because he's funny and creepy but he's also the consummate horror host.
Before we went to Anthologysville, we checked out the trailer for the original Poltergeist.