Thomas Ligotti and Jorge Luis Borges.
Well I do my best!
But it’s almost impossible to define what SF is and what it is not historically. With that in mind I nominate Homer, Dante and Milton. With a shout out going to Nabokov’s Pale Fire
I LOVED Ligotti until I read that long, bizarre essay of his about how the universe is meaningless and there is no god. Even if you are an atheist, you’ll be put to sleep by his endless rehashing of high school-level cliches about meaninglessness.