Alexandra of Lithuania
|Duchess consort of Masovia|
|Born||late 1360s or early 1370s|
|Died||20 April 1434|
|Noble family||Gediminids (by birth) |
House of Piast (by marriage)
|Spouse(s)||Siemowit IV, Duke of Masovia|
|Mother||Uliana of Tver|
Alexandra (Polish: Aleksandra, Lithuanian: Aleksandra; died 20 April 1434 in Płock) was the youngest daughter of Algirdas, Grand Duke of Lithuania, and his second wife, Uliana of Tver. Though Alexandra's exact date of birth is not known, it is thought that she was born in the late 1360s or early 1370s. In 1387, she married Siemowit IV, Duke of Masovia, and bore him thirteen children.
On 12 December 1385, few months after the Union of Krewo, Siemowit IV, Duke of Masovia, reached a compromise with king Jadwiga of Poland and her intended consort king Jogaila (Władysław II Jagiełło), brother of Alexandra. Siemowit IV agreed to cease his rival claims to the Kingdom of Poland, pay homage to Jadwiga and Jogaila, and to assume position of a hereditary vassal to the Polish Crown in exchange for 10,000 Prague groschen and fief Duchy of Belz. The agreement was solidified by marriage of Siemowit IV and Alexandra in 1387.
In her union with Siemowit, Alexandra bore 13 children—five sons and eight daughters.
Karol Piotrowicz, w: Polski Słownik Biograficzny/ Polish Biographical Dictionary. T. 1. Kraków: Polska Akademia Umiejętności – Skład Główny w Księgarniach Gebethnera i Wolffa, 1935, p. 66–67