Prince Aleksander Ostrogski (c. 1571–1603) was a nobleman of the Polish–Lithuanian Commonwealth. Son of voivode of Troki and Hetman Prince Konstanty Wasyl Ostrogski and Zofia Tarnowska h. Leliwa, the daughter of voivode of Ruthenia and Kraków Hetman Jan Amor Tarnowski h. Leliwa and Zofia Szydłowiecka h. Odrowąż. He was voivode of Wołyń since 1593 and starost of Pereiaslav. In 1592 he married Anna Kostka h. Dąbrowa a Roman Catholic. Aleksander stay the only son of Konstanty Wasyl Ostrogski who remained Orthodox. Together with his father he acted against the Union of Brest. He founded the Monastery of Holy Trinity in the village of Mezhirich. Aleksander was buried in the Church of Lord's Theophany in Ostróg.

Marriage and issue

Aleksander married in 1592 Anna Kostka h. Dąbrowa, the daughter of voivode of Sandomierz and podskarbi Jan Kostka h. Dąbrowa and Elżbieta Elenborg z Eilemberku and had five children: