With Jules Verne and Stanislav Lem the best known non-english SF writers of the 19th and 20th century respectively, some earlier notable SF writers who were eventually widely circulated in English include:
Ludvig Holberg Danish/Norwegian author publishing Niels Klim's underground travels in 1741. Describes a solar system inside the earth with several inhabited planets. Widely published in several european languages
Voltaire French writer and philosopher who wrote the 1792 short-story Micromégas where Earth is visted by two aliens from Saturn and Sirius.
Johannes Kepler German astronomer writing Somnium between 1620 and 1630. Contains detailed descriptions of how the earth would look like from the moon.
Cyrano de Bergerac French dramatist who wrote Comical history of the states and empires of the moon, published posthumously in 1657. Arthur C. Clarke credited this novel with the first description of rocket-powered space flight and the ramjet.
Lucian of Samosata (AD 125 - AD 180) a Syrian satirist writing in Greek, who wrote True History a satire of contemporary works which manages to include space travel, aliens and interplanetary warfare.