Prince Aleksander Ostrogski (Belarusian: Аляксандар Астрожскi Ukrainian: Олександр Острозький Lithuanian: Aleksandras Ostrogiškis) (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.

Aleksander stay the only son of Konstanty Wasyl Ostrogski who remained Orthodox.

Aleksander was buried in the Church of Lord's Theophany in Ostróg.

[1] 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:[2]