The Earthsea Quartet - Ursual LeGuin

Studied the first book when I was twelve; didn't remember much about it. The writing style is very dense, but not in an unfriendly way. It just goes very deeply into things. Some great fantasy concepts here, such as the language of magic, where everything is called by its "true name" rather than words being simply signifiers, so speaking it gives you power over reality. It struck me that each book is very self-contained and different from the others, unlike many fantasy series that give the impression of really being one long book cut into manageable sections. Deep and interesting and well-written; I still prefer The Left Hand of Darkness.

The Left Hand of Darkness - Ursula LeGuin

All-around brilliant. Interesting setting; good, developed characters (though not many); and ever third sentence is so good you want to read it aloud two or three times. And all the sociology and political stuff seems enduringly relevant. "A man who doesn't despise a bad government is a fool, and if there was such a thing on earth as a good government it would be a joy to serve it." It's (along with playing Final Fantasy XIII) made me keen to write some big fantasy or sci-fi story.