This is a great thread! Thanks to everyone who shared the books they've read.

David Eddings wrote the
Tamuli and the
Elenium series which together are six books, if I remember correctly. There is a character Mirtai who is from a race of people who are taller and larger than average, and she is described as a giantess. I can't remember which books she is in, but she is a central character and a warrior, and gets to kick some ass in a few battle scenes. In one she picks up a man and throws him down a flight of stairs!
Larry Niven wrote
Achilles Choice which has a female lead who is a sort of futuristic Olympian who has to choose whether or not to take some special drug which will enable her to become fast and strong enough to compete but which will cause her premature death. (Basically, I think. It's been a while since I read it.) Boris Vallejo did the cover art.
Timothy Zahn wrote some Star Wars books and Mara Jade is a muscular Jedi-woman. I think she's in
The Last Command.
Jack Vance wrote several amazon-types into some of his stories. There's a couple minor large, strong women in one of the books in the
Cadwal Chronicles (can't remember which one). In
Ports of Call there are two tall women "built like bulls" who stick around in the narrative for a while. And in
City of the Chasch there is a religious cult of priestesses who hate men and their leader is a truly formidable specimen who gets is a fight with the main character. Unfortunately for female muscle fans, Jack Vance's depiction of these women is generally not a flattering one, and they are all minor antagonists in the stories.
I'll probably remember a few more later, and I'll post those. In the meantime I've got some new books to acquire!