Edgar Allan Poe (1809-1849) is known for his mystery and horror short stories, but he also wrote in other genres, including science fiction. His best science fiction stories (in chronological order) are The Unparalleled Adventure of One Hans Pfaall, The Conversation of Eiros and Charmion, The Colloquy of Monos and Una, and Mellonta Tauta. We can also mention A Tale of the Ragged Mountains, Mesmeric Revelation, The Power of Words, and The Facts in the Case of M. Valdemar.
His only (complete) novel, The Narrative of Arthur Gordon Pym (1838), bordered on science fiction and inspired masterpieces such as Moby-Dick (1851) by Herman Melville, Twenty Thousand Leagues under the Sea (1870) and An Antarctic Mystery (1897) by Jules Verne. Edgar Allan Poe also wrote an essay on cosmology, Eureka: A Prose Poem (1849), that can be read as a philosophical science fiction work.