Christa Crutaire is a 6th-century harper in love with Judith (her Anglicized name). Christa and Judith sneak off to hear the SIdhe play music one night and get captured. They are held in Faerie for more than 1,000 years, but Christa steals a magical harp (Ceis, who is a great character in itself) and escapes sometime around 1800.
She opens a gate a couple of times to fight for Judith’s freedom, but gets her ass handed her by the Sidhe’s main bard. She is beginning to despair in the 1980’s because the gates seem to be closing, but a friend introduces her to heavy metal and she gets the idea this music may hold the key to defeating the Sidhe.
Then she forms an all-woman metal band, but they are beset by various problems.
Won’t say any more, Omniscient, but this is one of my favorite fantasy novels and I am not a fan of metal. I don’t why it isn’t better known. I think your lady will love it.
Speaking of Katherine Kerr, in addition to being an author in her own right she was/is the literary executor for Jo Clayton, who also specialized in “kickass female leads”. I don’t pretend to have anything near an encyclopedic knowledge of her writing, but the Diadem and Duel of Sorcery series might be worth a looksee (the latter being more along the fantasy line).
For a more complex version of Disney fantasy, I usually look to Patricia McKillip. The Forgotten Beasts of Eld is about a sorceress protecting/collecting unique magical beasts. The Book of Atrix Wolfe is about a wizard and cursed faerie princess who get tangled up in spells left over from past conflicts. The Riddle-Master trilogy actually has a male protagonist, but female secondary protagonist (and main character of the second book): it’s high magic, magical kingdoms, riddles and ancient mysteries, shapechangers, and end-of-the-world stuff.
Jack of Kinrowan is a modern fantasy retelling of Jack the Giant-slayer set in Ottowa, where the titular Jack is a woman, Jacky Rowan.
Sheri S Tepper’s True Game series is three trilogies, the first with a male protagonist, and the prequel and sequel trilogies with strong female protagonists. It’s set on a fantasy-like colony world where the settlers developed magic-like powers which they’ve used to indulge in frivolous gaming. It was written before she became such a strident feminist, although there’s some of that, too.
Andre Norton’s Witch World series has several books with strong female leads. I’d recommend Year of the Unicorn, about a young woman hiding her magical powers sent off as a bride to shapechanger mercenaries from a hidden, magical land. (It’s sequel, The Jargoon Pard, has a male protagonist.)
Of the aforementioned Marion Zimmer Bradley, I’d recommend Hawkmistress! as a stand-alone that’s fairly good. Her Darkover books are about a lost colony world where the inhabitants developed psychic powers and a feudal society. This one is set pre-recontact during a period of conflict, about a girl with beast telepathy.
I found her trilogy beginning with Moongather more approachable. It’s a fantasy story about a woman warrior with empathic powers over animals, struggling against an oppressive patriarchy dominated by male sorcerers.
Charles de Lint. Urban fantasy master. I find him a bit repetitive, but others may disagree. My personal entré was The Little Country, but take your pick; (IMO, again) they all pretty much tread the same ground*.
*YMMV, as I’ve hinted. CdL is very much respected as an urban fantasy author; I just find his stuff to kinda walk over the same themes over and over again. And yet, even I wind up going back to him when I want a little bit more from that particular well. So don’t hold it against him; he may be a one trick pony (IMO!!), but he does that one trick better than any other pony out there.
Those certainly are great value per page… hardcover copies count as weaponry and are heavy enough to be illegal in most countries. I picked one up in the airport simply on the basis of “cheapest for its size”, I didn’t like it enough to go and buy everything else in the series but it made for good hotel reading.
The Chicks in Chainmail anthologies feature short stories and can be a good way to pick up on a new author. A couple of them are available on Kindle.
Sanderson’s current series,** the Stormlight Archive**, is even better, and also features a very compelling female character as one of its two or three main protagonists. The second book of a projected 10-book series just came out, and unlike other writers I can think of, Sanderson actually pumps out his books at a fast and regular rate.
I have a huge amount of respect for Sanderson, both for the rigor and discipline of his writing, and for saving the Wheel of Time series. I mean, he managed to make *Egwene *a cool character. Egwene!
While Red Country is a standalone book, I would suggest reading it after Abercrombie’s First Law trilogy, in which a couple of the characters first feature prominently.
Also, if you liked Red Country but haven’t read that trilogy, I can recommend it very highly. Like Red Country - brutal, grey, bends/breaks any number of genre conventions, and still comes out a very satisfying story in the end. The first book is called The Blade Itself.
Tamora Pierce’s Tortall books. They’re Young Adult books but they are well written and good reads. Medieval-style sword n sorcery coming of age books with female teens working to fit into a man’s world - and being better than them.
Julian May’s Saga of Pliocene Exile (beginning with The Many-Colored Land) feels like fantasy, even though it’s technically science fiction. Characters from the future can take a one-way trip to Earth’s past, where they discover a pair of thriving alien cultures with psychic powers that resemble magic. There’s lots of politicking and romance and rebellion. There’s no specific protagonist, but in the huge cast of characters four of the most important are female.
Don’t think this has been mentioned before, but how about Robin Hobb’s Liveship trilogy? It has several plot lines, mainly following the various members of the Vestrit family, especially one of the daughters, Althea. It’s part of a longer series (the other books have a male lead, though still quite a few strong female characters), but it works well enough as a stand alone.
It’s set in, effectively, a long post-apocalypic fantasy world, in a society of traders of poorly understood magical relics (who own the titular liveships, which are what they sound like). What starts off as a family dispute soon gets tangled up in a civil war, until… well… that would be spoiling.
Also on the paranormal romance end - Deborah Harkness All Souls Triology is Twilight for grown ups. I’m sure someone has read these and hasn’t liked them, but my girlfriends have gobbled them up (the last book comes out this Summer).
Since we’re going broad with our fantasy, I can’t say enough about the Thursday Next series. It’s comedic, urban, alternate history fantasy, with a bit of sci-fi thrown in the first book, but it’s still fantasy.
Patricia C. Wrede has been mentioned, and I thoroughly enjoyed her epistolary novels with Caroline Stevermer, Sorcery and Cecilia. It’s a Regency romance/fantasy. Spritely, light, and enjoyable. Close to Ruritanian in its feel is Stevermer’s A College of Magics. I go back and read it every few years, and it’s held up remarkably well. Both of these have sequels worth reading.
Spindle’s End by Robin McKinley is by far her best light fantasy book. I’d steer clear of Deerskin though. Too painful, too many triggers, and too much feeling like she was working through some serious issues of her own.
Was going to recommend this. No dragons or princesses (I think) but an urban, highly literate, fantasy series. Really helps if the reader’s a comparative literature fan, as a lot of the plot and humor deal with changes to the texts of classics like Jane Eyre. Start with The Eyre Affair and hang on.