|Died||20 November 1986 (aged 93)|
|Doctoral advisor||Edmund Landau|
|Other academic advisors||Dmitry Grave|
|Doctoral students||Theodore Motzkin|
Stefan E. Warschawski
Alexander Markowich Ostrowski (Ukrainian: Олександр Маркович Островський; Russian: Алекса́ндр Ма́ркович Остро́вский; 25 September 1893, in Kiev, Russian Empire – 20 November 1986, in Montagnola, Lugano, Switzerland) was a mathematician.
His father Mark having been a merchant, Alexander Ostrowski attended the Kiev College of Commerce, not a high school, and thus had an insufficient qualification to be admitted to university. However, his talent did not remain undetected: Ostrowski's mentor, Dmitry Grave, wrote to Landau and Hensel for help.
Subsequently, Ostrowski began to study mathematics at Marburg University under Hensel's supervision in 1912. During the World War I he was interned, but thanks to the intervention of Hensel, the restrictions on his movements were eased somewhat, and he was allowed to use the university library.
After the war had ended Ostrowski moved to Göttingen where he wrote his doctoral dissertation and was influenced by Hilbert, Klein and Landau. In 1920, after having obtained his doctorate, Ostrowski moved to Hamburg where he worked as Hecke's assistant and finished his habilitation in 1922. In 1923 he returned to Göttingen, and in 1928 became Professor of Mathematics at Basel, until retirement in 1958. In 1950 Ostrowski obtained Swiss citizenship. After retirement he still published scientific papers until his late eighties.