The Chronicles of Thomas Covenant, the Unbeliever

The first series of books is a trilogy and comprises:

1. Lord Foul's Bane (1977)
2. The Illearth War (1978)
3. The Power That Preserves (1979)

An additional book titled Gilden-Fire is part of what was edited out of The Illearth War.

The trilogy is followed by The Second Chronicles of Thomas Covenant.