Hope Mirrlees, who opened that door between worlds with wit and wisdom.
Sylvia Townsend Warner, who brought elegance and grace.
Katherine Kurtz. I outgrew her books, but she was an innovator with her approach to High Magic, to religion in fantasy and in her expression of the High Mediaeval mode. I read everything with fantasy on the label in the 70s, and Kurtz was genuinely different: the fashion when she first appeared was still Heroic/swords and sorcery or 'low' style fantasy. She harked back to Morris and Dunsany, but in a far less mannered, far less forced mode.
Katherine Kerr (aberwyn). Other writers had done Celtic-influenced things, but Kit's Deverry books have a really solid, authentic, well-supported and internally consistent basis in real history, they aren't riven with new age thinking, historical wishful thinking or sentiment. And they're good.
Tanith Lee. Queen of the Universe. No arguments. She is easily as innovative a writer as Moorcock, yet she gets a fraction of the recognition and respect. (Yes, he has an important editorial side too. But I'm talking about books.)
Diana Wynne Jones.
Alis Rasmussen (kateelliott: The Labyrinth Gate prefigured the whole steampunk fantasy thing by nearly two decades. Nobody seems to remember.
Judith Tarr (dancinghorse). One of the earliest writers of mediaeval alternate history, yet we had to wait for a book by a man for the applause to start.
I could go on and on. But these are the writers whose books lit up my reading world. There are many more who I've discovered more recently, many women writing wonderful, innovative, intelligent fantasy. We need a banner and an anthem. We need a parade. Who would you honour and invite?