Black Christmas is considered one of the seminal slasher films, if it's the one I think it is. I haven't seen it, though.

I only watched it for the first time a year or two ago but I really liked it.

Gotta get the full uncensored version of The Wicker Man, though.

I saw The Wicker Man so long ago -- I might have been in high school, still? Definitely a classic. I need to see the original Black Christmas, too.

Theater of Blood (if it's the one I'm thinking of) is one I've enjoyed - Vincent Price and Diana Rigg? Shakespearean revenge?

Yes, that is the one. I had never heard of it, but looking at the description, it is one of the most appealing to me.

Thanks for the recs, everybody! Based on them, and my own tastes and tolerances, I think my top ten priorities in the collection will be:
The Vampire Lovers (Roy Ward Baker, 1970)
Let's Scare Jessica to Death (John D. Hancock, 1971)
Don't Look Now (Nicolas Roeg, 1973)
Sisters (Brian De Palma, 1973)
Theater of Blood (Douglas Hickox, 1973)
The Wicker Man (Robin Hardy, 1973)
Black Christmas (Bob Clark, 1974) (rewatch)
The Texas Chain Saw Massacre (Tobe Hooper, 1974)
The Tenant (Roman Polanski, 1976)
The Brood (David Cronenberg, 1979)

I likely will also check out It's Alive, which I suspect is quite bad, but it terrified me as a kid.

Speaking of terrified, of this list, I'm most wary of watching The Texas Chain Saw Massacre. How gory is it?

Note: I own Invasion of the Body Snatchers, which is why it is not here.

I'm most wary of watching The Texas Chain Saw Massacre. How gory is it?

Technically more grotesque than gory, but the grotesquerie is profound and disturbing. It's more unsettling than vomitous if that makes sense.

I'm most wary of watching The Texas Chain Saw Massacre. How gory is it?

It's been so long since I've watched it that I can't give you an accurate answer, but according to film lore (and wikipedia), Hooper originally hoped the film would get a PG rating because of the low level of gore.

(The MPAA laughed derisively and came back with an X rating.)

Technically more grotesque than gory, but the grotesquerie is profound and disturbing.

That matches my memories. Gore doesn't really bother me, but some of the grotesquerie in Texas Chainsaw Massacre was hard to look at.

For comparison, Jaws in 1975 got a PG rating.

Technically more grotesque than gory, but the grotesquerie is profound and disturbing.

Well, we'll see. I'll likely save it for last.

And now for the monthly Criterion expiration report. Not a ton leaving on October 31 that I feel I need to see. A few classics I've seen but wouldn't mind seeing again, a few collections I'm not really interested in (Jackie Chan, Albert Brooks), and a number of things I've never even heard of. And then of course the inevitable "homework" films I feel I should see. I must say, however, the longer this hellscape that is 2020 lasts, the more I lean toward watching by whim. So I think, beyond the movies I've flagged in the 70s Horror collection (which I presume will expire end of Nov/Dec), I won't be adding too much to my queue.

Somewhat intrigued by:
Don Siegel: The Killers (I don't know that I need to see another version of The Killers, but I usually like Siegel)
Peter Yates: The Deep (Is this as bad as the Rotten Tomatoes score would indicate?)
Alain Delon collection: Once a Thief (mostly because it takes place in SF)
Sofia Coppola: The Virgin Suicides (I didn't like this the first time I saw but I did read and like the book recently so I want to give it another chance.)

I tried to watch It's Alive in recent years and couldn't make it halfway through the movie. I do recall the marketing back in the 70s scaring the bejeezus out of me, however.