I'm hoping to sell a screenplay with Nyarlathotep as the central antagonist, with mentions and occasional threat of Azathoth. Apparently, some but not all Lovecraft characters are public domain. Would they be safe to use?

I was planning on drawing a few pictures of the likes of Cthulhu and Nyarlathotep on stream, because i thought i could remember hearing or reading that everything about them and the Yog-Sothothery was in the public domain, however i had just read that the works are copyright free but the image of the character(s) is not. Does anyone know the truth on this?

On January 1st 2022 one of Lovecraft's favorite authors, Algernon Blackwood, will enter public domain. In that regard it fits with some quotes from an interview with horror expert Andrew McQuade (this was almost ten years ago when the public domain date was still years away), who also has something to say about horror in general:

Satanic Pandemonium: Algernon Blackwood: An Interview with Andrew McQuade about Blackwood's Uncollected Fiction

"SP: Can you talk about why Blackwood is so neglected and why all of his works aren't printed in different fancy editions like the works of other horror writers such as Poe, Stoker and Lovecraft?

AM: Copyright. In the U.K., an author’s work goes out of copyright 70 years after their death. Most publishers, rather than pay the author’s family’s estate money, would rather just wait. I’ve heard tell from a number of sources that certain representatives of certain estates of certain authors have placed extraordinarily greedy demands on any works reissued. You can read into that what you will, but ultimately we’re the ones who lose out.

The main problem with all facets of horror, however, is that it’s dictated purely by commercial factors. There is very minimal state support for horror in the way that there is for certain other genres or causes. Recently, some of the made-for-TV horror from the BBC in the ‘70s has been reissued by the British Film Institute, but it’s very much a genre held to ransom by commercial whim. All the power in horror is held by an extremely conservative horror establishment, especially so in film, which means it’s very hard to actually get scared nowadays. Finding good material, in literature or film, takes a hell of a lot of searching. More searching than most of us, with day jobs and other commitments, have time for.

A lot has been done on Blackwood. Mike Ashley has done some wonderful things over the years and I cannot sing his praises enough. However, his research remains pretty much only within the reach of the die-hards. I’ve added bits and pieces to Wikipedia because I think everyone should be able to enjoy this work, not just collectors with bucket loads of cash to spare. That’s a kind of cultural elitism I object to. What’s needed is an institution of some sort to promote horror without the trappings of commercial necessity. Such institutes exist, for example, for gay and lesbian fiction/film, yet there’s nothing for horror. There are those who will say that horror is unimportant in the grand scheme, but it’s important in the small scheme, and it’s important to me. And I hate the way all that is great in horror is constantly brushed aside for the mediocrity enforced by the horror-establishment.

What I hope to do with Blackwood’s collected fiction, when the time is right, is put it out into the public domain, along with various other writers whose works I’ve collected. Their materials will all be annotated, arranged into order of publication, and accompanied with critical commentaries. I’d also like to include some illustrations to give them a visual appeal that will attract a larger audience. This is really how the horror establishment has kept the likes of Poe and Lovecraft alive in the public consciousness for so long and so well. I need to get more people on board to help me with this, then we can distribute this stuff on the net. The challenge is finding people who also want to keep this project free from commercialism, which has basically killed horror. Blackwood shouldn't just be the property of the elite. He wrote for everyone and everyone should still be able to enjoy him."

I've tried looking this up before, but I keep getting mixed messages and I'm not sure where to look for a solid answer. Some sources tell me they're all PD, others tell me there's a company that owns the rights to Lovecraft's works. And even then, I can't really get an answer as to which ones, if it's a half and half thing.

I'm especially curious if anyone owns the rights to the Nyarlathotep lore.

I know only the stuff created early on (e.g. Cthulhu, R'lyeh, Nyarlathotep) is in the public domain, but I've been unable to find a list of exactly which characters/entities/settings this includes.