Zander said:
Dragonlance series by Hickman & Weis
The Crystal Shard and possibly other Drizzt novels by R. A. Salvatore
Do people who aren't D&D players actually read these books? They seem to be popular among people who were getting into gaming around the time they were released, but among the older crowd that I know nobody has read them.
Black Company - One of the first really grim 'n gritty fantasy series.
Glen Cook's Garret Books - Very little else like them out there and certainly nothing half as good.
The Wheel of Time - I'm as fed up with RJ as everyone else, but the first five or so books were great and it was a very creative and unique world he created.
Diskworld - I'd have to agree with this one as well. So many classic characters, situations and just flat out funny.
The Belgariad by David Eddings - This might make it, but his later stuff hasn't been nearly as good in addition to largely being a retreading this series.
Mercedes Lackey's Valdemar books - I intensely dislike these myself (probably for similar reasons to why Conan style books tend not to be popular among the ladies), but they do seem to have carved a strong niche for themselves as female fan favorites.
Another Fine Myth - Pretty much THE Original humorous fantasy series.
The first 3 Books of the Thomas Covenant series - Yeah, he's one of the least likeable heroes in fantasy fiction. But I've found that a number of the ideas and themes from the books to have become quite iconic.
The Anita Blake Vampire Hunter Novels - Another possible, the title char has the potential to become a classic iconic character and while fantasy creature/magic in the modern world books are nothing new, these do seem to have struck a vein.
The Left Behind books - These have definitely found an audience, while perhaps not traditional fantasy, religious beliefs aside and not as a dig at them, they certainly fit into the category. They may turn out to be a fad, but I suspect they will have a lasting influence.
I'm not convinced quite frankly that the G.R.R.M's Fire & Ice books will become classics. While I've enjoyed them there is a certain something missing, there just isn't anything about them that feels iconic. The first thing that pops into my mind when I think about the series is its extreme brutality.