Countess Ada of Holland was a noblewoman born around 1188, known for her role in the medieval history of the County of Holland. She was the daughter of Count Floris III of Holland and Adelaide of Cleves. Ada became the wife of Count Henry I of Luxembourg, strengthening political ties between their regions. Ada's marriage produced several children, including Countess Sophie of Luxembourg. Her lineage played a significant role in the development of noble families in Holland and Luxembourg. Countess Ada's life reflects the intricate connections between European nobility during the 12th century.