Since Tanith Lee deserves to be known for much more than having been plagiarized, I thought I'd share some recommendations. She had a HUGE body of work, and I've seen it suggested that the reason she never became a household name in fantasy and science fiction is that she wrote so many things that were different from each other, rather than staying in one easily labeled niche. I've only begun to make a dent in her catalogue, but here's the stuff I liked the best.
Note: A lot of her stuff can be disturbing, and I can't remember everything well enough to give perfect trigger warnings.
Red as Blood and Redder Than Blood: These fairy tale collections are being talked about now for the title story, but my favorite is The Golden Ladder, an incredibly creepy and hot version of Rapunzel, or perhaps When the Clock Strikes, a horrifying beautiful take on Cinderella.
The Weird Tales of Tanith Lee: As you can see, I love her short stories. These are all the ones published in Weird Tales, which includes some of the above fairy tales (including When the Clock Strikes) but also Arthurian, steampunk and science fiction stories. It's a great sampler of all the things she could do.
Blood 20: One more short story collection! This one is (most of) her vampire stories, so I know you goths will like it! There are things erotic, fantastical and grotesque in here, but to me the most haunting is the tragically mundane The Vampire Lover.
The Secret Books of Paradys: In this series, an alternate history of Paris, bad things happen. Supernatural things, sexual things, horrifying things. And sometimes good things happen, such as a man saved by a Jewish sage an his beautiful daughter who then actually converts to Judaism.
The Secret Books of Venus: I've only read the first entry in this similar series about an alternate world version of Venice, but once again it leaves the reader feeling totally transported to this sometimes sinister, sometimes lovely place where romance and cruelty live next door to each other.
Vivia: This tragic medieval plague-influenced vampire story is maybe the darkest thing of hers I've read, but dear god can she paint a picture with words. Along with The Birthgrave (which I didn't like as much), George RR Martin definitely pulled a lot of Danaerys's story from the title character here.
Islands in the Sky: And now for something completely different- a children's book. I remember finding this at the library as a kid and wanting to cry when it was over, because it gave me an equal sense of wonder and happiness as The Lion the Witch and the Wardobe, which I hadn't known was possible and worried would never happen again.
...but if you're like me, you'll just see which of her books you find at the library and used bookstores. You may not love every single thing, but it will always be interesting!