Saint Waltrude (French: Waudru, Dutch: Waldetrudis) (d. April 9, c. 688) is the patron saint of Mons, Belgium, where she is known in French as Sainte Waudru, and of Herentals, Belgium, where she is known in Dutch as Sint-Waldetrudis or -Waltrudis. Both cities boast a large medieval church that bears her name.
Married to the Count of Hainault, she raised four children. After her husband retired to an abbey, she herself became a nun in 656. She founded her own convent (Sainte-Waudru) and the city of Mons grew around it.
The shrine of Saint Waltrude is kept in the collegiate church dedicated to her in Mons. Each year as part of the Ducasse de Mons festival, the shrine is placed on the car d'or, a gilded cart, and drawn by horses through the city streets.