Oles'ko (Ukrainian: Олесько; Polish: Olesko; Yiddish: אלעסק Alesk) is small town in Lviv Oblast (province) of western Ukraine.
It was the seat of the rebbes of Alesk, and also the birthplace of Jan III Sobieski, the King of Poland and Grand Duke of Lithuania.
The earliest mentioned Jewish community is in 1500. Oles'ko was the place of residence of tzadikim in the 19th century. In 1935 its Jewish population was 738.
Coordinates: 49°57′47″N 24°53′38″E / 49.96306°N 24.89389°E