Carlos Castenada ... father of magical realism ... well, along with Marquez... the genre owes so much to South America
Though I think MR is rather distinct from fantasy (and I'm a huge Marquez fan), I am reminded of the following old literary joke concerning the influence of Latin American writers on MR:
"Q: What is magical realism?
A: A fantasy novel where everybody is speaking Spanish."
I also totally want to second, third, and fourth the previous recommendation for Rushdie (who, to the best of my knowledge, doesn't speak Spanish).