Hedwig Jagiellon (1408%E2%80%931431)

Hedwig Jagiellon was a Polish and Lithuanian princess, and a member of the Jagiellon dynasty. For most of her life she, as the only child of Wladyslaw Jagiello, was considered to be heiress of the Polish and Lithuanian thrones. After the birth of Jagiellos sons in 1424 and 1427, Hedwig had some support for her claims to the throne. She died in 1431 amidst rumors that she was poisoned by her stepmother Sophia of Halshany.

She was the only daughter of King of Poland and Supreme Duke of Lithuania Wladyslaw Jagiello by his second wife, Anna of Celje, daughter of William, Count of Celje, and Anna of Poland. Anna of Celje was a granddaughter of King Casimir III of Poland and therefore a Piast heiress. Thanks to his marriage to her in 1402, Jagiello relegitimized his rule as King of Poland after the death of his first wife, Hedwig , who reigned as King of Poland. Jagiellos and Annas only daughter, born in 1408, was named after Queen Hedwig.

Source: Wikipedia