Far too many to properly list! I greatly admire writers like Stephen King, who came from what could be called nothing to become one of the most popular and well known authors after going through a great deal of pain and misfortune in his life and continues to work and find a way to create new stories.
I admire writers like J.K.Rowling, who managed to plan out her series so completed before even the creation of the halfway point and who managed to find success in a foreign market from a simple idea.
I admire writers like Neil Gaiman, who is so unique and inspiring and creative I don't feel I can do him justice in a summary.
I admire anyone who is able to write for pure enjoyment and to share their stories because they love what they do.