Terry Pratchet is great!
Tad Williams is another fantasy author I recommend. His "Memory, Sorrow, and Thorn" series are marvellous and very original for a fantasy world (unless we compare it to, yes, A Song of Ice and Fire

). Oh, it's one of the few books I've read where the protagonist is my favourite character.
The Witcher by Polish writer Andrzej Sapkowski are another amazing series. Dark Fantasy in its purest form. Yes, the videogame is based on these books. I don't know how many books have been translated into English though, all of them except the last one are already translated into Spanish

.
And, I can't say it enough, A Song of Ice and Fire by George R. R. Martin.
Hart's Hope by Orson Scott Card is interesting. It's his only fantasy book I think, unless you consider the Alvin Maker series fantasy books. It's curious, this writer has some books I consider fantastic and many books I consider crap... Ender's Game, Speaker for the Dead, Hart's Hope and, specially, Songmaster are really good books. I'd stick to those.
And then there's science-fiction if you like it, but there are too many great books to name them. At least compared to fantasy books where we don't really have that many.