13. The Reveal Of Korob And Sylvia From Catspaw (1967)
1967's Catspaw is another genuinely tense and interesting script - and why shouldn't it be? It was written by Robert Bloch, the man who gave us the novel Psycho, and a long time correspondent of H.P. Lovecraft. Bloch's own stories are often influenced by Lovecraft's mythos about the Old Ones, and this story is no exception, given Spock's references to what he sees when he tries to link his mind to those of the aliens Korob and Sylvia. So imagine our surprise (and mortification) when the aliens are finally revealed not to be multi-tentacled beings so alien to our senses that they can barely be looked at, but this: Yeah, that can barely be looked at, all right. Honestly. What is it with this show and puppets, anyway?!