J. R. R. Tolkien
Tolkien was born in 1892, and lived through both World Wars. His own experience as a soldier in World War I had a profound effect on his writing, and was a memory that he carried with him for the rest of his life.
Tolkien's writing falls mainly in the genre of fantasy. He spent his life creating the world of Middle Earth, in which his Lord of the Rings trilogy is set. He filled notebook after notebook with information about that world, and many of those notebooks have been published after his death, offering even details about that world to Tolkien's faithful readers. Tolkien's belief about writing fiction was that the author is a "subcreator," someone participating in the creative work begun by God as recorded in Genesis. Tolkien believed, therefore, that the author should take great care and give meticulous attention to his creation, just as God gave to the universe he created. You can read more about Tolkien's view on subcreation in the essay "On Fairy Stories."