Great thread, by the way.

Some of favorites have already been mentioned, so I won't re-list them.

Silmarillion by JRR Tolkien & Christopher Tolkien

The Camulod Chronicles by Jack Whyte
1. The Skystone
2. The Singing Sword
3. The Eagles Brood
4. The Fort at the Rivers Bend
5. The Saxon Shore
6. The Sorcerer
(He also wrote Uther & The Lance Thrower, but these 1st 6 are best. They are all half fiction.)

Enjoy