Ishak Bey Kraloğlu

Ishak Bey Kraloğlu
Burial	Serres, Ottoman Empire
House	Kotromanić
Father	Thomas of Bosnia
Mother	Catherine of Bosnia
Religion	Islam previously Roman Catholicism

Ishak Bey Kraloğlu (Serbo-Croatian: Ishak-beg Kraljević/Исхак-бег Краљевић; died after 1493), christened Sigismund Tomašević (Сигисмунд Томашевић), was a Bosnian prince, the last known member of the House of Kotromanić and an Ottoman statesman. He was captured during the Ottoman conquest of Bosnia in 1463, after which he converted to Islam and became a companion of Mehmed the Conqueror, eventually rising to the post of sanjak-bey.

Sigismund was born into the House of Kotromanić, the Bosnian royal dynasty, as the son of King Thomas and his second wife, Queen Catherine. The King notified the authorities of the Republic of Ragusa of the birth of a son in 1449, most likely referring to Sigismund; the Ragusans sent gifts to the parents as well as the infant according to custom. His birth was followed by that of a sister, Catherine. Sigismund also had an older half-brother, Stephen Tomašević, born of the canonically invalid first marriage of their father. Sigismund's maternal family may have been poised to claim the crown for him, but it was nevertheless Stephen who became King of Bosnia following the death of their father in July 1461. Sigismund's maternal grandfather, Stjepan Vukčić Kosača, the kingdom's most powerful magnate, realized that Bosnia needed an adult monarch due to the imminent threat of Ottoman conquest, and refrained from pressing Sigismund's claim. Although often said to have resided at the castle of Kozograd above Fojnica with his sister and mother during King Stephen's reign, it seems unlikely that the King would not have wanted his half-siblings at his side, at the royal court in Jajce – especially since Sigismund was probably seen as heir presumptive.

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