Focus on Scotty's sexism and it's a chilling story for all the wrong reasons.
Yes, it's the 1960s, sexism was rampant*, but most TREK episodes didn't go bananas over it. Only "The Lights of Zetar" and "Turnabout Intruder" dare to be overt in their flaunting of sexism, and the former also includes Scotty (again). I'll get to those stories' reviews later on... but in "Wolf", Scotty has some dialogue about hurting himself because of a female coworker. Kirk and McCoy hinge on this dialogue as well as part of the setup. It drives me nuts because I can't stand these characters of the future being sexist, but at the same time the goal was to frame Scotty and have a malevolent force cause havoc.
The direction in this story is terrific - it is engaging, the fear is palpable - especially after the proceedings move to the ship. The guest cast are terrific in their roles as well. Nowhere is a bad actor to be found, but John Fiedler - along with James Doohan (more later) - steals the show as the possessed villain. The story holds up extremely well in this regard, and seeing him in other shows reveals Fiedler to be a great character actor as well...
Using Jack the Ripper as a basis for an incorporeal critter that uses emotions to feed on (and would be revisited in "Day of the Dove", and in other sci-fi shows) is done better in those other shows, but in "Wolf" - despite Scotty - holds up extremely well for its age.
Considering it's the 1960s, though, this sort of sexism was prevalent in the media. And I am not blaming the actors or writers as much as the mores of the time. And, given that the original pilot had a strong #1 (Majel Barrett) and the execs hated that character as she fought so many stereotypes... It cannot be helped that TOS was sexist at times. The actors cannot be blamed.
But James Doohan really puts in a fantastic performance in this story (ditto for TNG's "Relics", despite a questionable plot that diminishes Scotty, also sees a top-of-the-line performance, making one wonder why Mr Doohan didn't get work outside of TREK as much as he had, because he's a darn good character actor, and he did so many voiceovers for aliens in TREK as
Without the overt sexism, which was - again - partly needed but ends up feeling overtly contrived - this episode would score a 10.
* (recall that the original pilot's #1 was a logical female officer, which the execs promptly nixed because her presence upended so many stereotypes and cliches accorded women that they could not deal with it... and the miniskirt was about sexual liberation, not male-dominated sexism by