The Great Alta series by Jane Yolen -- I picked up Sister Light, Sister Dark from the library as a young fantasy reader, and the image of two women, born of the same essence, twisting their opposing colored hair to strangle their enemy has stayed with me ever since. A couple of years ago I tracked down the whole series since the images continue to echo in my mind.
The Time Master Trilogy by Louise Cooper -- Tarod, you were the man of my fantasies for years to come, even despite being a chaos god. I loved you all the more for it!
Greenfire by Louise Titchener -- I decided to Google this author because I don't remember ever reading anything by her again, and this was reportedly a one-time foray into fantasy for her. Apparently, she was a romance writer, which makes sense because there was a definite focus on the love story in this--like chick lit for fantasy lovers. I like chick lit, I like fantasy. Why not?
The Fionaver Tapestry series by Guy Gavriel Kay -- I haven't read this series in a long time, but it's one of my favorites in the realm of fantasy because it deals with the real world and a fantasy world, a theme that particularly appeals to me. As if, yeah, that could happen sings through my soul.
Mists of Avalon by Marion Zimmer Bradley -- I read you twice. Twice! And you're huge, like bible-length. But I love retellings where Morgan le Fey is good, and I love anything having to do with the King Arthur legends.
The Wayfarer Redemption series by Sara Douglass -- Oh Axis, I was so mad when you left Faraday, but it all worked out... for you anyway. Unfortunately, Ms. Douglass passed away a few years ago, but her work lives on. I followed this series for years and still love it.
Onion Girl by Charles de Lint -- Gotta have some Charles on here. I've read a lot of his books, but this one's my favorite, and Jilly Coppercorn is the cutest name.
Good Omens: The Nice and Accurate Prophecies of Agnes Nutter, Witch by Neil Gaiman and Terry Pratchett -- Who doesn't love laughing over the birth of Satan. But really, I love this and have read it several times.
Many Waters by Madeleine L'Engle -- My favorite of her YA fantasy series following the adventures of the Murry's. I love the mix of science and magic merging with Christian theology.