Countess Ermesinde of Luxembourg was a prominent noblewoman born around 1186. She was the daughter of Count Henry IV of Luxembourg and Countess Matilda of Vianden. Ermesinde played a significant role in the political landscape of her time, particularly through her marriage to Count Siegfried I of Luxembourg, which strengthened alliances in the region. Ermesinde is best known for her contributions to the development of Luxembourg City and her efforts in promoting the rights of her children. After her husband's death, she became a key figure in managing the family's estates and ensuring the continuation of their lineage, which would later lead to the rise of the House of Luxembourg.