I recently finished The Night Land, by William Hope Hodgson.
This is considered a classic of weird literature, and with reason. The unnamed Narrator lives in the Last Redoubt, a mighty pyramid-shaped city which is one of the last great fortresses of humanity in the time after the sun has gone dark and the Earth has ceased rotating. The Redoubt is surrounded by the Night Land, a dark wilderness filled with all manner of horrifying monsters, but is protected by a ring of light powered by the Earth-Current. The Narrator is also a telepath, and begins to receive telepathic signals from another Redoubt, inhabited by the reincarnation of his Beloved from an earlier age - and the Earth-Current of the Lesser Redoubt is failing. Desperate to save his love, he sets off into the Night Land to find her.
This is a work with great strengths and great flaws. Strengths first: it is a uniquely imaginative vision, a wildly creative idea. The Night Land is just a splendidly weird place, full of monsters and horrors and forces of evil and good. Like Lovecraft's Cthulhu Mythos, it makes you want to write your own stories set there, and I gather people have.
That said, I'm not sure it should really be classified under "weird literature". The structure of the story is more in the vein of an Arthurian romance. The Narrator is a knight, in literal armor, equipped with a high-tech sword - a "Diskos" that's basically a chainsaw-axe - venturing into strange realms to rescue his lady-love. Although the land he ventures into is redolent of the Weird, most of what actually happens in that land would not be out of place in a more traditional tale. There are exceptions - the House of Silence, the strange unnamed spirit, the doorways in space. But this is more of a science fiction/Arthurian romance hybrid. Not that that's a bad thing.
I should add that one of the common criticisms of this book is the writing style. The framing of the story is that this is supposedly the dream or vision of an 18th-century English nobleman, and he writes like one, all thees and thous and lo!s. I actually liked that; I thought it was an effective distancing device, helping to highlight how strange and alien this other world is.
On to the flaws. First, to get it out of the way, the sexism. The Narrator's lady love is at least a real character, not just a prize to be won and bedded, but the relationship between her and the Narrator would not be considered at all healthy in the modern day. And by that I mean he beats her, and this is presented as a good thing, which she's eventually grateful for. Seriously.
Also, I thought it was lacking in atmosphere. There is lots of potential atmosphere in the setting - the darkness, the fires from the Earth, the bizarre monsters - but the writing doesn't really draw it out. Very little is actually described, beyond being called "the Watcher in the Northeast" or what have you. I don't think we ever even learned the Beloved One's hair color.
Finally, the book is way, way too long. It could have been profitably cut by half to two-thirds. I gather Hodgson wrote an abridged version, called The Dream of X, but I've not read it.
All in all, while I can definitely see why this is considered a classic - especially considering it was written in 1912 - it's not something I would recommend for the casual reader, as its weaknesses overbalance its strengths. 3/5 stars.