Jadwiga of Poland

Jadwiga Andegaweńska' (1374 1399) became the King of Poland on 16 October 1384 at the age of eleven. She was crowned as a king, not queen. Her royal title was: " Hedvigis Dei Gracia Rex Poloniae, necnon terrarum Cracoviae, Sandomiriae, Syradiae, Lanciciae, Cuyaviae, Pomeraniaeque domina et heres," (Jadwiga the grace of God, the Polish king, and heir to the land in Kraków, Sandomierz, Sieradz, Łęczyca, Kujawy and Pomerania). She was the daughter of Louis Hungarian, King of Poland and Hungary).
Jadwiga married a Lithuania Grand Duke, Jogaila (Władysław Jagiełło) on 18 February 1386. After her death during childbirth on 17 July 1399, her husband became the King Ladislaus II of Poland.
In 1997 she was made a saint by Pope John Paul II.