Stefan Bastyr (17 August 1890 – 6 August 1920) was a Polish aviator and military pilot, one of the pioneers of the Polish aviation. He is credited with the first military flight in the history of the Polish Air Force on 5 November 1918, almost a week before Poland officially regained her independence, at the opening stages of the Polish-Ukrainian War.

Initially he was a military pilot in Austria-Hungary during World War I. From February 1916 he served as an observer in Flik 10 reconnaissance squadron on the eastern front, from December 1917 in Flik 12D on Austro-Italian front. In 1918 he himself trained as a pilot and was assigned to Flik 37P from June 1918. He undertook about 100 sorties during the war and scored at least 1 air victory on 4 June 1916.

In the Polish Air Force, he took part in the Battle of Lwów (1918). He performed the first military flight of Polish aircraft, on 5 November 1918 against Ukrainian troops at Persenkowka station, along with observer Janusz de Beaurain (he flew Oeffag C.II,^[1] or according to other publications, Hansa-Brandenburg C.I^[2]). He died in an aircrash of Fokker D.VII in Lviv (probably due to a hear failure) during the Battle of Lwów (1920) and is buried at the Łyczaków cemetery in Lwów (modern Lviv).